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Other anatomical features of a long bone including the diaphysis primary hiv infection symptoms rash buy cheap starlix 120 mg online, epiphysis, epiphysial plate, articular cartilage, periosteum, and endosteum 7. Stages of intramembranous ossification; some bones that form in this way; and how far this process has progressed by birth 2. How stresses on bones remodel them throughout life; the difference between interstitial and appositional growth 9. The four cell types in bone tissue; their functions, origins, and locations in the tissue 2. Organic and inorganic components of the bone matrix; their respective contributions to bone strength; and the significance of the helical arrangement of collagen fibers in bone 3. Osteon structure and the relationship of osteonic bone to interstitial and circumferential lamellae 7. The difference between a stress fracture and a pathological fracture; stages in the healing of a fractured bone; and approaches to the clinical treatment of fractures 2. Causes of osteoporosis; its risk factors, pathological effects, diagnosis, treatment, and prevention 7. The purpose and process of mineralization of osseous tissue, and the identity of the cells that carry it out 2. The purpose and process of bone resorption, and the identity of the cells and cell secretions that carry it out 3. Functions of calcium in the body; the normal range of blood calcium concentration; Testing Your Recall 1. The spurt of growth in puberty results from cell proliferation and hypertrophy in a. A bone increases in diameter only by growth, the addition of new surface lamellae. The transitional region between epiphysial cartilage and the primary marrow cavity of a young bone is called the. In endochondral ossification, bone tissue is formed by the calcification of preexisting cartilage. Most osteocytes of an osteon are far removed from blood vessels, but still receive blood-borne nutrients. A 50-year-old business executive decides he has not been getting enough exercise for the last several years. Within 2 years, he is spending many of his weekends hiking with a heavy backpack and camping in the mountains. How does the regulation of blood calcium concentration exemplify negative feedback and homeostasis Describe how the arrangement of trabeculae in spongy bone demonstrates the unity of form and function. Understanding skeletal anatomy also depends on knowledge of the terms for body regions and cavities described in atlas A. One reason is the development of sesamoid 1 bones-bones that form within 1 sesam = sesame seed; oid = resembling K nowledge of skeletal anatomy will be useful as you study later chapters. It provides a point of reference for studying the gross anatomy of other organ systems because many organs are named for their relationships to nearby bones. The subclavian artery and vein, for example, lie adjacent to the clavicle; the temporalis muscle is attached to the temporal bone; the ulnar nerve and radial artery travel beside the ulna and radius of the forearm; and the frontal, parietal, temporal, and occipital lobes of the brain are named for adjacent bones of the cranium. Understanding how the muscles produce body movements also depends on knowledge of skeletal anatomy. Additionally, the positions, shapes, and processes of bones can serve as landmarks for clinicians in determining where to give an injection or record a pulse, what to look for in an X-ray, and how to perform physical therapy and other clinical procedures. Appendicular Skeleton Pectoral girdle (4 bones) Scapulae (2) Upper limbs (60 bones) Humerus (2) Radius (2) Ulna (2) Pelvic girdle (2 bones) Hip bones (2) Lower limbs (60 bones) Femurs (2) Patellae (2) Tibiae (2) Fibulae (2) Tarsal bones (14) Metatarsal bones (10) Phalanges (28) Carpal bones (16) Metacarpal bones (10) Phalanges (28) Clavicles (2) the skeleton (fig. The axial skeleton, which forms the central supporting axis of the body, includes the skull, auditory ossicles (middle-ear bones), hyoid bone, vertebral column, and thoracic cage (ribs and sternum). The appendicular skeleton includes the bones of the upper limb and pectoral girdle and the bones of the lower limb and pelvic girdle. The patella (kneecap) is the largest of these; most of the others are small, rounded bones in such locations as the hands and feet (see fig. It is important to know the names of these bone markings because later descriptions of joints, muscle attachments, and the routes traveled by nerves and blood vessels are based on this terminology. You can easily palpate (feel) many of the bones and some of their details through the skin. Rotate your forearm, cross your legs, palpate your skull and wrist, and think about what is happening beneath the surface or what you can feel through the skin. You will gain the most from this chapter (and indeed, the entire book) if you are conscious of your own body in relation to what you are studying. Briefly describe each of the following bone features: a condyle, crest, tubercle, fossa, sulcus, and foramen. Although it may seem to consist only of the mandible (lower jaw) and "the rest," it is composed of 22 bones and sometimes more. The largest, with an adult volume of about 1,350 mL, is the cranial cavity, which encloses the brain. Other cavities include the orbits (eye sockets), nasal cavity, oral (buccal) cavity, middleand inner-ear cavities, and paranasal sinuses. They are connected with the nasal cavity, lined by mucous membranes, and filled with air. They lighten the anterior portion of the skull and act as chambers that add resonance to the voice. The latter effect can be sensed in the way your voice changes when you have a cold and mucus obstructs the travel of sound into the sinuses and back. Some of the details will mean more after you study cranial nerves and blood vessels in later chapters. The cranium is a rigid structure with an opening, the foramen magnum (literally "large hole"), where the spinal cord meets the brain. In skulls prepared 2 3 4 for study, the calvaria is often sawed so that part of it can be lifted off for examination of the interior. The relatively shallow anterior cranial fossa is crescent-shaped and accommodates the frontal lobes of the brain. The posterior cranial fossa is deepest and houses a large posterior division of the brain called the cerebellum. There are eight cranial bones: 1 frontal bone 2 parietal bones 2 temporal bones 1 occipital bone 1 sphenoid bone 1 ethmoid bone the Frontal Bone the frontal bone extends from the forehead back to a prominent coronal suture, which crosses the crown of the head from right to left and joins the frontal bone to the parietal bones (see figs. The frontal bone forms the anterior wall and about onethird of the roof of the cranial cavity, and it turns inward to form nearly all of the anterior cranial fossa and the roof of the orbit. In some people, the edge of this foramen breaks through the margin of the orbit and forms a supraorbital notch. The smooth area of the frontal bone just above the root of the nose is called the glabella. A parietal foramen sometimes occurs near the corner of the lambdoid and sagittal sutures (see fig. A pair of slight lateral thickenings, the superior and inferior temporal lines, form an arc across the parietal and frontal bones (see fig. They mark the attachment of the large, fan-shaped temporalis muscle, a chewing muscle that converges on the mandible. The Temporal Bones If you palpate your skull just above and anterior to the ear-that is, the temporal region-you can feel the temporal bone, which forms the lower wall and part of the floor of the cranial cavity (fig. The temporal bone derives its name from the fact that people often develop their first gray hairs on the temples with the passage of time. It bears two prominent features: (a) the zygomatic process, which extends anteriorly to form part of the zygomatic arch, described later; and (b) the mandibular fossa, a depression where the mandible articulates with the cranium. Small sutural bones are often seen along the sagittal and lambdoid sutures, like little islands of bone with the suture lines passing around them. Internally, the parietal and frontal bones have markings that look a bit like aerial photographs of river tributaries (see fig. These represent places where the bone molded itself around blood vessels of the meninges. The petrous12 part can be seen in the cranial floor, where it resembles a little mountain range separating the middle cranial fossa from the posterior fossa (fig. The internal acoustic meatus, an opening on its posteromedial surface, allows passage of a nerve that carries signals for hearing and balance from the inner ear to the brain. On the inferior surface of the petrous part are two prominent foramina named for the major blood vessels that pass through them (see fig.

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The application of any of these criteria still results in falsepositive and false-negative diagnoses hiv infection rates in europe starlix 120 mg low cost. In the era of "omic" sciences (genomics, proteomics, transcriptomics, metabolomics, etc. New Zealand Guidelines for Rheumatic Fever: Diagnosis, Management and Secondary Prevention of Acute Rheumatic Fever and Rheumatic Heart Disease: 2014 Update. Clinical practice guideline for the diagnosis and management of group A streptococcal pharyngitis: 2012 update by the Infectious Diseases Society of America. Although this poses challenges, it should not detract from pursuing this line of research. Indeed, recent experience suggests that adapting higher technology testing to resource-poor settings, including via point-of-care testing, may be more feasible than relying on more traditional laboratory testing. Clinical profile of acute rheumatic fever patients in a tertiary care institute in present era. New Zealand guidelines for the diagnosis of acute rheumatic fever: small increase in the incidence of definite cases compared to the American Heart Association Jones criteria. Doppler echocardiography and the early diagnosis of carditis in acute rheumatic fever. Are all recurrences of "pure" Sydenham chorea true recurrences of acute rheumatic fever Rheumatic fever in a high incidence population: the importance of monoarthritis and low grade fever. Global, regional, and national age-sex specific all-cause and cause-specific mortality for 240 cases of death, 1990e2013: a systemic analysis for the Global Burden of Disease Study 2013. Brazilian guidelines for the diagnosis, treatment and prevention of rheumatic fever. Consensus guidelines on pediatric acute rheumatic fever and rheumatic heart disease. Controlling acute rheumatic fever and rheumatic heart disease in developing countries: are we getting closer Mobile device for disease diagnosis and data tracking in resource-limited settings. Special writing group of the committee on rheumatic fever, endocarditis, and Kawasaki disease of the council on cardiovascular disease in the young of the American heart association. Comparison of throat cultures and rapid strep tests for diagnosis of streptococcal pharyngitis. The human immune response to streptococcal extracellular antigens: clinical, diagnostic, and potential pathogenetic implications. In addition, patients should be monitored regularly for response to treatment and physicians should be mindful of contraindications to medications and drug allergies. Rashes following previous antibiotic administration may lead to patients erroneously being labeled as allergic to penicillin (the vast majority are not). Penicillin allergy can be investigated by skin testing, preferably with input from an allergist. Begin with 50e60 mg/kg/day, increasing if needed to 80e100 mg/ kg/day (4e8 g/day in adults) given in 4e5 divided doses/day. Orally in children: 1 monthe12 years: 1e3 mg/kg/day (maximum 100e200 mg/day) in 1e2 divided doses. For heart failure/atrial fibrillation Seek advice from specialist regarding duration of use. For severe carditis, heart failure, or pericarditis with effusion (if acute heart surgery is not indicated). Child: 15 mcg/kg initially, then 5 mcg/kg after 6 h, then 3e5 mcg/kg/ dose (maximum 125 mcg) 12 hourly. Resting allows reduction of workload on the heart and may prevent progression of the inflammatory process. Further education by primary healthcare staff, using culturally appropriate educational materials, should be continued once the patient has returned home. If mild, the mitral regurgitation in patients with carditis can diminish or disappear with bed rest. If the patient continues to exercise and the patient does not receive penicillin, rheumatic activity may persist and mitral regurgitation can worsen. The excessive workload on the heart of a patient with severe rheumatic mitral regurgitation produces a situation analogous to that of a child with active carditis and a mild valve lesion being forced to exercise continuously. Severe mitral regurgitation, with its associated hemodynamic overload, can aggravate rheumatic activity. The correction of the valve lesion results in removal of the excessive cardiac workload caused by the regurgitation. Although naproxen is recommended as the treatment of choice, aspirin may still be used in resource constrained settings where it is easily available and cheaper, with close observation for any potential side effects. Most patients require treatment for only 1e2 weeks, but some cases may need 6e8 weeks. In cases where prolonged antiinflammatory therapy with aspirin is used (>2 weeks), drug levels should be monitored (if available) as the risk of salicylate toxicity is increased. All degrees of carditis, including subclinical carditis,13 require hospitalization. However, there is little objective evidence to prove that they are beneficial over and above bed rest, fluid restriction, and heart failure medications. Infective endocarditis should be considered in all patients who are very ill or have a persistently high fever (see Chapter 16). Serial blood cultures should be taken and echocardiography will help to define the presence of intracardiac vegetations. Atrial fibrillation and infective endocarditis are usually associated with chronic valve disease. Thiazide diuretics or spironolactone may be added if the initial response to loop diuretics is inadequate. If heart failure symptoms persist, intravenous diuretics and vasodilators (and inotropes if evidence of cardiogenic shock) may be required while awaiting cardiac surgery, although there is no evidence that any of these agents reduce mortality. Both dobutamine and dopamine have been shown to be effective inotropic agents in children with circulatory failure especially in low income countries where milrinone may not be available due to cost issues. There were a total of 8 deaths and 5 patients needing surgery, with 5/8 deaths and 4/5 surgical interventions occurring in the corticosteroid group. In a small study of 24 patients, prednisone was shown to favorably affect clinical response (fall in heart rate and fall in clinical score) compared to aspirin. Surgery can be lifesaving in patients where the principal cause of severe hemodynamic deterioration is ruptured chordae tendineae causing severe mitral regurgitation. Occasionally, the pulmonary edema is unilateral (seen in approximately 2% of cases), most often affecting the right upper lobe and can be confused with pneumonia (particularly if the patient has concurrent fever). This is mostly seen in chordal rupture with a flail anterior mitral valve leaflet as a complication of rheumatic valvulitis. Patients who receive 10 days of penicillin, bed rest, and/or hospitalization have significantly better neurocognitive outcomes. If, however, movements interfere with normal activities, or place the patient at risk of injury such as falling over, or are extremely distressing to the patient or their family, treatment can be considered. A multidisciplinary approach is ideal and may include pharmacotherapy, occupational therapy, physiotherapy, and support with schooling (missed school days and poor school performance can be a significant issue). Several dopamine 2 (D2) receptor antagonists have been utilized in worldwide studies to treat chorea, the most common being the neuroleptics haloperidol and pimozide. This can be treated with an anticholinergic such as diphenhydramine along with withdrawal or reduction in dosage of the offending drug. Medication should be continued for 2e 4 weeks after chorea has subsided, and then withdrawn. A multidisciplinary approach is best and should include referral to psychiatry, psychology, and neurology specialists. The efficacy and safety of naproxen in acute rheumatic fever: the comparative results of 11-year experience with acetylsalicylic acid and naproxen. Naproxen as an alternative to aspirin for the treatment of arthritis of rheumatic fever: a randomized trial. Accelerated junctional rhythm in children with acute rheumatic fever: is it specific to the disease Asymptomatic rhythm and conduction abnormalities in children with acute rheumatic fever: 24-hour electrocardiography study. Outpatient Follow-up All patients should receive regular review and outpatient follow-up that should be arranged before discharge.

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In this frontal section of the femur antiviral essential oil blend order starlix 120mg overnight delivery, the trabeculae of spongy bone can be seen oriented along lines of mechanical stress applied by the weight of the body or the pull of a muscle. Mesenchymal cells line up along the blood vessels, become osteoblasts, and secrete a soft collagenous osteoid19 tissue (prebone) (fig. Calcium phosphate and other minerals crystallize on the collagen fibers of the osteoid tissue and harden the matrix. Continued osteoid deposition and mineralization squeeze the blood vessels and future bone marrow into narrower and narrower spaces. As osteoblasts become trapped in their own hardening matrix, they become osteocytes. While the foregoing processes are occurring, more mesenchyme adjacent to the developing bone condenses and forms a fibrous periosteum on each surface. At the surfaces, osteoblasts beneath the periosteum deposit layers of bone, fill in the spaces between trabeculae, and create a zone of compact bone on each side as well as thicken the bone overall. This process gives rise to the sandwichlike structure typical of a flat cranial bone-a layer of spongy bone between two layers of compact bone. The figures are drawn to different scales, with the highest magnification and detail at the beginning and backing off for a broader overview at the end of the process. With the aid of chapter 8, name at least two specific bones other than the clavicle that would form by this process. Most bones of the body develop in this way, including the vertebrae, ribs, sternum, scapula, pelvic girdle, and bones of the limbs. This figure uses a metacarpal bone from the palmar region of the hand as an example because of its relative simplicity, having only one epiphysial plate (growth center). Many other bones develop in more complex ways, having an epiphysial plate at both ends or multiple plates at each end, but the basic process is the same. Note the layers of osteoid tissue, osteoblasts, and fibrous periosteum on both sides of the bone. Mesenchyme develops into a body of hyaline cartilage, covered with a fibrous perichondrium, in the location of a future bone. For a time, the perichondrium produces chondrocytes and the cartilage model grows in thickness. In a primary ossification center near the middle of this cartilage, chondrocytes begin to inflate and die, while the thin walls between them calcify. These deposit a thin collar of bone around the middle of the cartilage model, 2 Intramembranous ossification also plays an important role in the lifelong thickening, strengthening, and remodeling of the long bones discussed next. Throughout the skeleton, it is the method of depositing new tissue on the bone surface even past the age where the bones can no longer grow in length. With the aid of chapter 8, name at least two specific bones that would have two epiphysial plates (proximal and distal) at stage 5. As chondrocytes in the middle of the model die, their lacunae merge into a single cavity. Osteoblasts also arrive and deposit layers of bone lining the cavity, thickening the shaft. As the bony collar under the periosteum thickens and elongates, a wave of cartilage death progresses toward each end of the bone. Osteoclasts in the marrow cavity follow this wave, dissolving calcified cartilage remnants and enlarging the marrow cavity of the diaphysis. Soon, chondrocyte enlargement and death and vascular invasion occur in the epiphysis of the model as well, creating a secondary ossification center. In the metacarpal bones, as illustrated in the figure, this occurs in only one epiphysis. The secondary ossification center hollows out by the same process as the diaphysis, generating a secondary marrow cavity in the epiphysis. In bones with two secondary ossification centers, one center lags behind the other, so at birth there is a secondary marrow cavity at one end while chondrocyte growth has just begun at the other. The joints of the limbs are still cartilaginous at birth, much as they are in the 12-week fetus in figure 7. The plate persists through childhood and adolescence and serves as a growth zone for bone elongation. Bone Elongation To understand growth in length, we must return to the epiphysial plates mentioned earlier (see fig. From infancy through adolescence, an epiphysial plate is present at one or both ends of a long bone, at the junction between the diaphysis and epiphysis. On X-rays, it appears as a translucent line across the end of a bone, since it is not yet ossified (fig. The red-stained regions are calcified at this age, whereas the elbow, wrist, knee, and ankle joints appear translucent because they are still cartilaginous. The epiphysial plate consists of typical hyaline cartilage in the middle, with a transitional zone on each side where cartilage is being replaced by bone. Minerals are deposited in the matrix between the columns of lacunae and calcify the cartilage. These are not the permanent mineral deposits of bone, but only a temporary support for the cartilage that would otherwise soon be weakened by the breakdown of the enlarged lacunae. Within each column, the walls between the lacunae break down and the chondrocytes die. This converts each column into a longitudinal channel (clear spaces in the figure), which is immediately invaded by blood vessels and marrow from the marrow cavity. Osteoblasts line up along the walls of these channels and begin depositing concentric lamellae of matrix, while osteoclasts dissolve the temporarily calcified cartilage. This region, farthest from the marrow cavity, consists of typical hyaline cartilage with resting chondrocytes, not yet showing any sign of transformation into bone. A little closer to the marrow cavity, chondrocytes multiply and arrange themselves into longitudinal columns of flattened lacunae. Next, the chondrocytes cease to multiply and begin to hypertrophy (enlarge), much like they 2 3 the process of bone deposition in zone 5 creates a region of spongy bone at the end of the marrow cavity facing the metaphysis. This micrograph shows the transition from cartilage to bone in the growth zone of a long bone. But around the perimeter of the marrow cavity, continuing ossification converts this spongy bone to compact bone. Osteoblasts lining the aforementioned channels deposit layer after layer of bone matrix, so the channel grows narrower and narrower. They lay down matrix in layers parallel to the surface, not in cylindrical osteons like those deeper in the bone. This process produces the surface layers of bone called circumferential lamellae, described earlier. This is achieved by osteoclasts of the endosteum dissolving tissue on the inner bone surface. Thus, flat bones develop by intramembranous ossificaton alone, whereas long bones develop by a combination of the intramembranous and endochondral methods. Bone Remodeling In addition to their growth, bones are continually remodeled throughout life by the absorption of old bone and deposition of new. It releases minerals into the blood for uses elsewhere; reshapes bones in response to use and disuse; and repairs microfractures, preventing them from developing into catastrophic bone failure similar to metal fatigue. Wolff observed that these lines were similar to the ones engineers knew of in mechanical cranes. The effect of stress on bone development is quite evident in elite tennis players, in whom the cortical bone of the racket arm is up to 35% thicker than that of the other arm. Long bones of the limbs are thickest at midshaft, where they are subjected to the greatest stress. Bone remodeling comes about through the collaborative action of osteoblasts and osteoclasts. If a bone is little used, osteoclasts remove matrix and get rid of unnecessary mass. If a bone is heavily used or stress is consistently applied to a particular region of a bone, osteoblasts deposit new osseous tissue and thicken it. Consequently, the comparatively smooth bones of an infant or toddler develop a variety of surface bumps, ridges, and spines (described in chapter 8) as the child begins to walk. On average, bones have a greater density and mass in athletes and people engaged in heavy manual labor than they do in sedentary people.

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The future thumb and great toe are both directed superiorly hiv infection in zambia buy starlix online, and the future palms and soles face each other medially. Then rotate your forearms so the thumbs face away from each other (laterally) and the palms face upward. The lower limbs rotate in the opposite direction, medially, so that the soles face downward and the great toes become medial. So even though the thumb and great toe (digit I of the hand and foot) start out facing in the same direction, these opposite rotations result in their being on opposite sides of the hand and foot (fig. This rotation also explains why the elbow flexes posteriorly and the knee flexes anteriorly, and why (as you will see in chapter 10) the muscles that flex the elbow are on the anterior side of the arm, whereas those that flex the knee are on the posterior side of the thigh. It is normally well above the ground, as evidenced by the shape of a wet footprint. The transverse arch includes the cuboid, cuneiforms, and proximal heads of the metatarsal bones. Excessive weight, repetitious stress, or congenital weakness of these ligaments can stretch them, resulting in pes planus (commonly called flat feet or fallen arches). A comparison of the flat-footed apes with humans underscores the significance of the human foot arches (see Deeper Insight 8. Name any four structures of the pelvis that you can palpate and describe where to palpate them. Name all the bones that articulate with the talus and describe the location of each. Footprints preserved in a layer of volcanic ash in Tanzania indicate that hominids walked upright as early as 3. This bipedal locomotion is possible only because of several adaptations of the human feet, legs, spine, and skull. These features are so distinctive that paleoanthropologists (those who study human fossil remains) can tell with considerable certainty whether a fossil species was able to walk upright. As important as the hand has been to human evolution, the foot may be an even more significant adaptation. While apes are flat-footed, humans have strong, springy foot arches that absorb shock as the body jostles up and down during walking and running. The tarsal bones are tightly articulated with one another, and the calcaneus is strongly developed. The great toe is not opposable as it is in most Old World monkeys and apes, but it is highly developed so it provides the "toe-off" that pushes the body forward in the last phase of the stride (fig. For this reason, loss of the great toe has a more crippling effect than the loss of any other toe. While the femurs of apes are nearly vertical, in humans they angle medially from hip to knee (fig. We lock our knees when standing, allowing us to stand erect with little muscular effort. Apes cannot do this and cannot stand on two legs for very long without tiring- much as you would if you tried to maintain an erect posture with your knees slightly bent. In apes and other quadrupedal (four-legged) mammals, the abdominal viscera are supported by the muscular abdominal wall. In humans, the viscera bear down on the floor of the pelvic cavity, and a bowl-shaped pelvis with an inturned floor is necessary to support their weight. This has resulted in a narrower pelvic outlet-a condition that creates pain and difficulty in giving birth to such large-brained infants. Human adaptations for bipedalism are best understood by comparison to our close living relative, the chimpanzee, which is not adapted for a comfortable or sustained erect stance. The largest muscle of the buttock, the gluteus maximus, serves in apes primarily as an abductor of the thigh-that is, it moves the leg laterally. In humans, however, the ilium has expanded posteriorly, so the gluteus maximus originates behind the hip joint. This changes the function of the muscle-instead of abducting the thigh, it pulls the thigh back in the second half of a stride (pulling back on your right thigh, for example, when your left foot is off the ground and swinging forward). Two other buttock muscles, the gluteus medius and gluteus minimus, extend laterally in humans from the surface of the ilium to the greater trochanter of the femur (fig. The actions of all three gluteal muscles, and the corresponding evolutionary remodeling of the pelvis, account for the smooth, efficient stride of a human as compared with the awkward, shuffling gait of a chimpanzee or gorilla when walking upright. Their center of gravity is anterior to the hip joint when they stand; they must make a constant muscular effort to keep from falling forward, and they fatigue quickly. Our australopithecine ancestors probably could travel all day with relatively little fatigue. The human head is balanced on the vertebral column with the gaze directed forward. The cervical curvature of the spine and remodeling of the skull have made this possible. The forelimbs of apes are longer than the hindlimbs; indeed, some species such as the orangutan and gibbons hold their long forelimbs over their heads when they walk on their hind legs. By contrast, our forelimbs are shorter than our hindlimbs and far less muscular than the forelimbs of apes. No longer needed for locomotion, our forelimbs have become better adapted for carrying objects, holding things closer to the eyes, and manipulating them more precisely. The location and extent of the occipital bone, its basilar part, and the names and locations of its foramina, canals, and surface protrusions 10. The location and extent of the sphenoid bone; its wings, body, pterygoid plates, clinoid processes, and foramina; its relationships with the pituitary gland and nasal apertures 11. The location and extent of the ethmoid bone; its part in defining the nasal fossae; and the locations of its plates, foramina, air cells, and nasal conchae 12. Names of the eight different facial bones; which ones are solitary and which are bilaterally paired 13. The location and extent of the maxilla; its foramina, alveoli, and alveolar and palatine processes; and the suture that joins the right and left maxillae 14. The location and extent of the palatine bones; their foramina; and their part in partially defining the walls of the nasal cavity and orbit 15. Structure of the palate, including the hard and soft regions and the contributions of the palatine processes and palatine bones 16. The location and extent of the zygomatic bones, and the temporal process and main foramen of each 17. The inferior nasal concha and why it is distinguished from the superior and middle conchae 20. The location and extent of the vomer; contributions of the vomer and ethmoid bone to the nasal septum 21. Structure of the mandible, including the body, ramus, and angle; its two main processes and the notch between them; its foramina, symphysis, protuberance, and spines 22. The locations and names of the auditory ossicles; location and features of the hyoid bone; and functions of these bones 24. The number of vertebrae and intervertebral discs in the vertebral column (spine) 2. Four curvatures of the adult spine; which ones are present at birth; and when and how the others develop 3. The five classes of vertebrae and the number of vertebrae in each class; the system of numbering them; and why the number of vertebrae in a child differs from the number at 30 years of age and beyond 5. The structure and function of intervertebral discs; which vertebrae have discs between them and which ones do not 9. Anatomical features of the sacrum, including its foramina, crests, canal and hiatus, auricular surface and sacroiliac joint, promontory, and alae 10. How the ribs articulate with the vertebrae, including variations from the top to bottom of the rib cage 8. The difference between the axial and appendicular skeletons, and the bones in each category 2. The typical number of named bones in an adult; why this number differs in newborns and children; and why the number varies among adults 3. Names of the various outgrowths, depressions, articular surfaces, cavities, and passages in bones 8.

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Poliomyelitis is caused by the poliovirus side effects of antiviral meds cheap starlix line, which destroys motor neurons in the brainstem and anterior horn of the spinal cord. Signs of polio include muscle pain, weakness, and loss of some reflexes, followed by paralysis, muscular atrophy, and sometimes respiratory arrest. Historically, polio afflicted many children who contracted the virus from swimming in contaminated pools. For a time, the polio vaccine nearly eliminated new cases, but the disease has lately begun to reemerge among children in some parts of the world because of antivaccination politics. It is marked not only by the degeneration of motor neurons and atrophy of the muscles, but also sclerosis (scarring) of the lateral regions of the spinal cord-hence its name. Most cases occur when astrocytes fail to reabsorb the neurotransmitter glutamate from the tissue fluid, allowing it to accumulate to a neurotoxic level. Sensory and intellectual functions remain unaffected, as evidenced by the accomplishments of astrophysicist and best-selling author Stephen Hawking (fig. Despite near-total paralysis, he had a slowly progressing form of the disease, remained intellectually undiminished, and communicated with the aid of a speech synthesizer and computer. Tragically, many people are quick to assume that those who have lost most of their ability to communicate their ideas and feelings have few ideas and feelings to communicate. Before we discuss those specific nerves, however, it is necessary to be familiar with the structure of nerves and ganglia in general. A nerve is a cordlike organ composed of numerous nerve fibers (axons) bound together by connective tissue (fig. If we compare a nerve fiber to a wire carrying an electrical current in one direction, a nerve would be comparable to an electrical cable composed of hundreds of wires carrying currents in opposite directions. A nerve contains anywhere from a few nerve fibers to (in the optic nerve) a million. Nerves usually have a pearly white color and resemble frayed string as they divide into smaller and smaller branches. As we move away from the spinal nerves proper, the smaller branches are called peripheral nerves, and their disorders are collectively called peripheral neuropathy. External to the neurilemma, each fiber is surrounded by a basal lamina and then a thin sleeve of loose connective tissue called the endoneurium. In most nerves, the fibers are gathered in bundles called fascicles, each wrapped in a sheath called the perineurium. The perineurium is composed of up to 20 layers of overlapping, squamous, epithelium-like cells. Several fascicles are then bundled together and wrapped in an outer epineurium to compose the nerve as a whole. The epineurium consists of dense irregular connective tissue and protects the nerve from stretching and injury. Nerves have a high metabolic rate and need a plentiful blood supply, which is furnished by blood vessels that penetrate these connective tissue coverings. Which of the descriptive terms for nerves have similar counterparts in muscle histology Individual nerve fibers show as tiny red dots, each surrounded by a light ring of myelin. Both types can be classified as somatic or visceral and as general or special depending on the organs they innervate (table 13. Purely sensory nerves, composed only of afferent fibers, are rare; they include nerves for smell and vision. Most nerves, however, are mixed nerves, which consist of both afferent and efferent fibers and therefore conduct signals in two directions. Among the neurosomas are bundles of nerve fibers leading into and out of the ganglion. Thus, spinal nerves C1 through C7 emerge superior to the correspondingly numbered vertebrae (nerve C5 above vertebra C5, for example); nerve C8 emerges inferior to vertebra C7; and below this, all the remaining nerves emerge inferior to the correspondingly numbered vertebrae (nerve L3 inferior to vertebra L3, for example). Proximal Branches Each spinal nerve arises from two points of attachment to the spinal cord. In each segment of the cord, six to eight nerve rootlets emerge from the anterior surface and converge to form the anterior (ventral) root of the spinal nerve. Another six to eight rootlets emerge from the posterior surface and converge to form the posterior (dorsal) root (figs. A short distance away from the spinal cord, the posterior root swells into a posterior (dorsal) root ganglion, which contains the neurosomas of sensory neurons (fig. There is no corresponding ganglion on the anterior root because the neurosomas are in the anterior horns of the spinal cord. The posterior root ganglion contains the neurosomas of unipolar sensory neurons conducting signals from peripheral sense organs toward the spinal cord. Below this is the anterior root of the spinal nerve, which conducts motor signals away from the spinal cord, toward peripheral effectors. The spinal nerve is a mixed nerve, carrying sensory signals to the spinal cord by way of the posterior root and ganglion, and motor signals out to more distant parts of the body by way of the anterior root. The anterior and posterior roots are shortest in the cervical region and become longer inferiorly. Distal Branches Distal to the vertebrae, the branches of a spinal nerve are more complex (fig. Thus, each spinal nerve branches on both ends-into anterior and posterior roots approaching the spinal cord, and anterior and posterior rami leading away from the vertebral column. The posterior ramus innervates the muscles and joints in that region of the spine and the skin of the back. The larger anterior ramus innervates the anterior and lateral skin and muscles of the trunk, and gives rise to nerves of the limbs. In the thoracic region, it forms an intercostal nerve, which travels along the inferior margin of a rib and innervates the skin and intercostal muscles (thus contributing to breathing). Sensory fibers of the intercostal nerve branches to the skin are the most common routes of viral migration in the painful disease known as shingles (see Deeper Insight 13. Motor fibers of the intercostal nerves innervate the internal oblique, external oblique, and transverse abdominal muscles. Note that each posterior root divides into several rootlets that enter the spinal cord. A segment of the spinal cord is the portion receiving all the rootlets of one spinal nerve. Cross section Arachnoid mater Dura mater Rootlets Posterior root Posterior root ganglion Anterior root In the labeled rootlets of spinal nerve C5, are the nerve fibers afferent or efferent They are components of the sympathetic nervous system and are discussed more fully in section 15. The spinal nerve roots that give rise to each plexus are indicated in violet in each illustration. Some of these roots give rise to smaller branches called trunks, anterior divisions, posterior divisions, and cords, which are color-coded and explained in the individual figures. Two of the nerves arising from these plexuses, the radial and sciatic, are sites of unique nerve injuries described in Deeper Insight 13. Somatosensory means that they carry sensory signals from bones, joints, muscles, and the skin, in contrast to sensory input from the viscera or from special sense organs such as the eyes and ears. Somatosensory signals are for touch, heat, cold, stretch, pressure, pain, and other sensations. The motor function of these nerves is primarily to stimulate the contraction of skeletal muscles. They also innervate the bones of the corresponding regions, and carry autonomic fibers to some viscera and blood vessels, thus adjusting blood flow to local needs. The following tables identify the areas of skin innervated by the sensory fibers and the muscle groups innervated by the motor fibers of the individual nerves. The muscle tables in chapter 10 provide a more detailed breakdown of the muscles supplied by each nerve and the actions they perform. You may assume that for each muscle, these nerves also carry sensory fibers from its proprioceptors. Predict the consequences of a surgical accident in which a phrenic nerve is severed.

Syndromes

• Immune deficiency
• Signs of dehydration
• Blood in the stools
• Awareness and planning
• Coughing up foul-smelling, greenish or dark phlegm (sputum) or phlegm that has pus or blood
• Fluid deprivation test (limiting fluids to see if the urine volume decreases)
• Bone marrow biopsy (may show the cancer has spread)

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These axons collect into small fascicles that leave the nasal cavity through pores (cribriform foramina) in the ethmoid bone natural antiviral herbs starlix 120 mg otc. Olfactory cells are the only neurons directly exposed to the external environment. This triggers action potentials in the axon of the olfactory cell, and a signal is transmitted to the brain. Some odorants, however, act on nociceptors of the trigeminal nerve rather than on olfactory cells. Projection Pathways When olfactory fibers pass through the roof of the nose, they enter a pair of olfactory bulbs beneath the frontal lobes of the brain (fig. Here they synapse with the dendrites of neurons called mitral cells and tufted cells. Olfactory cell axons reach up and mitral and tufted cell dendrites reach down to meet each other in spheroidal clusters called glomeruli (fig. All olfactory fibers leading to any one glomerulus come from cells with the same receptor type; thus each glomerulus is dedicated to a particular type of odor. Higher brain centers interpret complex odors such as chocolate, wine, perfume, or coffee by decoding signals from a combination of odor-specific glomeruli. This is similar to the way our visual system decodes all the colors of the spectrum using input from just three color-specific receptor cells of the eye. Their axons form bundles called olfactory tracts, which run caudally along the underside of the frontal lobes. Most fibers of the olfactory tracts end in various regions of the inferior surface of the temporal lobe regarded as the primary olfactory cortex. It is noteworthy that olfactory signals can reach the cerebral cortex directly, without first passing through the thalamus; thus, this is an extrathalamic13 pathway. Even in olfaction, however, some signals from the primary olfactory cortex continue to a relay in the thalamus on their way to olfactory association areas elsewhere. The primary olfactory cortex of each cerebral hemisphere relays signals to the contralateral hemisphere, so all further processing is mirrored on both sides of the brain even if an odor is initially detected in only one nasal fossa. On both sides, signals are relayed to the amygdala, hippocampus, insula, and hypothalamus, which interact in complex ways to associate a present odor with olfactory memories and emotional responses. Thus, the odor of certain foods, a perfume, a hospital, or decaying flesh can evoke strong memories, emotional responses, and visceral reactions such as sneezing or coughing, the secretion of saliva and stomach acid, or vomiting. The orbitofrontal cortex, just above the eyes, also receives signals from the primary olfactory cortex. This region also integrates odor, taste, and vision into an overall impression of the desirability or acceptability of food. Most areas of olfactory cortex also send fibers back to the olfactory bulbs by way of neurons called granule cells. Granule cells 13 Physiology Humans do not, as commonly supposed, have a poorer sense of smell than other mammals; that notion arose from certain unsubstantiated nineteenth-century assumptions of Paul Broca and Sigmund Freud and suffered from confirmation bias in twentiethcentury and even more recent research. We have only about onethird as many functional olfactory genes as rodents do, but we have more complex olfactory bulbs and orbitofrontal cortex-the brain regions where odor signals are interpreted. Humans outperform rodents and dogs for some odors and underperform them for others. Our sense of smell is much more sensitive than our sense of taste; we can detect odor concentrations as low as a few parts per trillion. Humans have about 400 types of odor receptors; each olfactory cell has only one receptor type and therefore binds only one odorant. With various combinations of input, however, most people can distinguish 2,000 to 4,000 different odors; some, such as world-class food and wine experts, can distinguish up to 10,000. Attempts to group these into odor classes have been inconclusive and controversial; the names for some suggested classes have included pungent, floral, musky, and earthy. Our olfactory sense is very subject to "top-down" influences of emotional and cognitive states, so the same odorant and concentration may smell different to us under different circumstances. On average, women are more sensitive to odors than men are, and they are measurably more sensitive to some odors near the time of ovulation as opposed to other phases of the menstrual cycle. The first step in smell is that an odorant molecule must bind to a receptor on one of the olfactory hairs. Hydrophilic odorants diffuse freely through the mucus of the olfactory epithelium and bind directly to a receptor. Hydrophobic odorants are transported to the receptor by an odorant-binding protein in the mucus. An effect of this feedback is that odors can change in quality and significance under different conditions. Food may smell more appetizing when you are hungry, for example, than when you have just eaten or when you are ill. List the primary taste sensations and discuss their adaptive significance (survival value). What brain regions serve the sense of smell and how do they differ in their olfactory functions Hearing is a response to vibrating air molecules, and equilibrium is the sense of body orientation, movement, and balance. Both senses reside in the inner ear, a maze of fluid-filled passages and sensory cells. We will study how the fluid is set in motion and how the sensory cells convert this motion into an informative nerve signal. Sound is produced by a vibrating object such as a tuning fork, a loudspeaker, or the vocal cords. They collide with other molecules just ahead of them, and energy is transferred from molecule to molecule until it reaches the eardrum. No one molecule moves very far; they simply collide with each other like billiard balls until finally, some molecules collide with the eardrum and make it vibrate. The sensations we perceive as pitch and loudness are related to the physical properties of these vibrations. Loudness Loudness is the perception of sound energy, intensity, or the amplitude of vibration. In the speaker example, amplitude is a measure of how far forward and back the cone vibrates on each cycle and how much it compresses the air molecules in front of it. Loudness is expressed in decibels (dB), with 0 dB defined by a sound energy that corresponds to the threshold of human hearing. Thus, 10 dB is 10 times threshold, 20 dB is 100 times threshold, 30 dB is 1,000 times threshold, and so forth. At most frequencies, the threshold of pain is 120 to 140 dB, approximately the intensity of a loud thunderclap. Prolonged exposure to sounds greater than 90 dB can cause permanent loss of hearing. It is determined by the frequency at which the sound source, eardrum, and other parts of the ear vibrate. One movement of a vibrating object back and forth is called a cycle, and the number of cycles per second (or hertz, Hz) is called frequency. The most sensitive human ears, particularly in children, can hear frequencies from 20 to 20,000 Hz, but most of us cannot hear over that broad a range. In this range, we can hear sounds of relatively low energy (volume), whereas sounds above or below this range must be louder to be audible, as reflected in the steeply rising curves at both ends of the violet range in figure 16. Threshold of pain 120 100 Loudness (decibels) Music 80 60 40 20 0 Threshold of hearing All sound Speech 16. The first two are concerned only with transmitting sound to the inner ear, where vibration is converted to nerve signals. Outer Ear the outer (external) ear is essentially a funnel for conducting airborne vibrations to the tympanic membrane (eardrum). It begins with the fleshy auricle (pinna) on the side of the head, shaped and supported by elastic cartilage except for the earlobe, which is mostly adipose tissue. The auricle is an arrangement of named whorls and recesses that direct sound into the auditory canal (fig. How would the shape of this graph change in a case of moderate hearing loss between 200 and 5,000 Hz The auditory canal (external acoustic meatus) is the passage leading through the temporal bone to the tympanic membrane.

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Sectioning a tissue reduces a three-dimensional structure to a series of two-dimensional slices functional assessment of hiv infection questionnaire discount generic starlix canada. You must keep this in mind and try to translate the microscopic image into a mental image of the whole structure. An experienced viewer, however, recognizes that the separated pieces are parts of a single tube winding its way to the organ surface. Note that a grazing slice through a boiled egg might miss the yolk, just as a tissue section might miss the nucleus of a cell even though it was present. Many anatomical structures are longer on one axis than another-the humerus and esophagus, for example. A section cut on a slant between a longitudinal and cross section is an oblique section. Liquid tissues such as blood and soft tissues such as spinal cord may be prepared as smears, in which the tissue is rubbed or spread across the slide rather than sliced. Classify each of the following into one of the four primary tissue classes: the skin surface, fat, the spinal cord, most heart tissue, bone, tendons, blood, and the inner lining of the stomach. What is the term for a thin, stained slice of tissue mounted on a microscope slide A bone and blood vessel are used to relate two-dimensional sectioned appearance to threedimensional structure. Would you classify the egg sections in the previous figure as longitudinal, cross, or oblique sections Epithelial6 tissue consists of a sheet of closely adhering cells, one or more cells thick, with the upper surface usually exposed to the environment or to an internal space in the body. Epithelium covers the body surface, lines body cavities, forms the external and internal linings of many organs, and constitutes most gland tissue. The epidermis of the skin, for example, is a barrier to infection, and the inner lining of the stomach protects its deeper tissues from stomach acid and enzymes. Epithelia absorb chemicals from the adjacent medium; nutrients, for example, are absorbed through the epithelium of the small intestine. All substances leaving the blood are selectively filtered through the epithelium that lines the blood vessels; all urinary waste is filtered through epithelia of the kidneys. Epithelia are provided with nerve endings that sense stimulation ranging from a touch on the skin to irritation of the stomach. Epithelial cells closest to the connective tissue typically exhibit a high rate of mitosis. This allows epithelia to repair themselves quickly-an ability of special importance in protective epithelia that are highly vulnerable to such injuries as skin abrasions and erosion by stomach acid. Between an epithelium and the underlying connective tissue is a layer called the basement membrane. The basement membrane serves to anchor an epithelium to the connective tissue; it controls the exchange of materials between the epithelium and the underlying tissues; and it binds growth factors from below that regulate epithelial development. The surface of an epithelial cell that faces the basement membrane is its basal surface, the one that faces away from it toward the body surface or the internal cavity (lumen) of an organ is the apical surface, and between these two, the "sidewall" of a cell is called the lateral surface. Epithelia are classified into two broad categories-simple and stratified-with four types in each category. In a simple epithelium, every cell is anchored to the basement membrane, whereas in a stratified epithelium, some cells rest on top of other cells and do not contact the basement membrane (fig. In this and subsequent tables, each photograph is accompanied by a labeled drawing of the same specimen. The drawings clarify cell boundaries and other relevant features that may otherwise be difficult to see or identify in photographs or through the microscope. Each figure indicates the approximate magnification at which the original photograph was made. Each is enlarged much more than this when printed in the book, but selecting the closest magnification on a microscope should enable you to see a comparable level of detail (resolution). Three types of simple epithelia are named for the shapes of their cells: simple squamous8 (thin scaly cells), simple cuboidal (squarish or round cells), and simple columnar (tall narrow cells). In the fourth type, pseudostratified columnar, not all cells reach the surface; the shorter cells are covered by the taller ones. This epithelium looks stratified in most tissue sections, but careful examination, especially with the electron microscope, shows that every cell reaches the basement membrane-like trees in a forest, where some grow taller than others but all are anchored in the soil below. Simple columnar and pseudostratified columnar epithelia often have wineglass-shaped goblet cells that produce protective the cells and extracellular material of an epithelium can be loosely compared to the bricks and mortar of a wall. The extracellular material ("mortar") is so thin, however, that it is barely visible with a light microscope, and the cells appear pressed very close together. Epithelia are avascular7 (without blood vessels)-there is no room for them between the cells. Pseudostratified columnar epithelium is a special type of simple epithelium that gives a false appearance of multiple cell layers. Note that these traditional terms describe the frontal appearance, but all three are polygonal when viewed from above. These cells have an expanded apical end filled with secretory vesicles; their product becomes mucus when it is secreted and absorbs water. The basal part of the cell is a narrow stem, like that of a wineglass, that reaches to the basement membrane. Three of the stratified epithelia are named for the shapes of their surface cells: stratified squamous, stratified cuboidal, and stratified columnar epithelia. It is sometimes called by an older name, transitional epithelium, that arose from a misunderstanding that it represented a transitional stage between stratified squamous and stratified columnar epithelium. Stratified columnar epithelium is rare and of relatively minor importance-seen only in places where two other epithelial types meet, as in limited regions of the pharynx, larynx, anal canal, and male urethra. The most widespread epithelium in the body is stratified squamous epithelium, which deserves further discussion. Its deepest layer of cells are cuboidal to columnar, and include mitotically active stem cells. Their daughter cells push toward the surface and become flatter (more scaly) as they migrate farther upward, until they finally die and flake off. You can easily study exfoliated cells by scraping your gums with a toothpick, smearing this material on a slide, and staining it with iodine for microscopic examination. A similar procedure is used in the Pap smear, an examination of exfoliated cells from the cervix for signs of uterine cancer (see fig. A keratinized (cornified) epithelium, found in the epidermis, is covered with a layer of dead compressed cells. These cells, called keratinocytes, are packed with the durable protein keratin and coated with a waterrepellent glycolipid. The skin surface is therefore relatively dry; it retards water loss from the body; and it resists penetration by disease organisms. This type provides a surface that is, again, abrasionresistant, but also moist and slippery. These characteristics are well suited to resist stress produced by chewing and swallowing food and by sexual intercourse and childbirth. The answer relates to the fact that urine is usually acidic and hypertonic to the intracellular fluid. It would tend to draw water out of the cells by osmosis and kill them if there were nothing to protect them. On the upper surface of an umbrella cell, the outer phospholipid layer of the plasma membrane is thicker than usual and has dense patches called lipid rafts with embedded proteins called uroplakins. Uroplakins are impermeable to urine and protect the urothelium, including the cytoplasm of the umbrella cell itself. When the bladder is empty and relaxed, these plaques fold at the hinges (like folding a laptop computer) and drop into the cell interior for storage, and the cell bulges upward as seen in figure 5. As the bladder fills with urine, the hinges open (like opening the computer), the plaques spread out over the surface to protect the cell, and the umbrella cells become thinner and flatter. Not surprisingly, this type of epithelium is best developed in the bladder, where it is subject to prolonged contact with stored urine. Distinguish between simple and stratified epithelia, and explain why pseudostratified columnar epithelium belongs in the former category despite its superficial appearance.

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Each is divided into an intercartilaginous part between the costal cartilages and an interosseous part between the bony part of the ribs hiv infection rates in california quality starlix 120 mg. The innermost intercostal muscles vary in number, as they are sometimes absent from the upper thoracic cage. Their fibers run in the same direction as the internal intercostals, and they are presumed to serve the same function. The internal and innermost intercostals are separated by a fascia that allows passage for intercostal nerves and blood vessels (see fig. However, they also contribute to enlargement and contraction of the thoracic cage and thus add to the air volume that ventilates the lungs. Many other muscles of the chest and abdomen contribute significantly to breathing: the sternocleidomastoid and scalenes of the neck; pectoralis major and serratus anterior of the chest; latissimus dorsi of the lower back; internal and external obliques and transverse abdominal muscle; and even some of the anal muscles. In inspiration, the intercartilaginous part aids in elevating the ribs and expanding the thoracic cavity; in expiration, the interosseous part depresses and retracts the ribs, compressing the thoracic cavity and expelling air; the latter occurs only in forceful expiration, not in relaxed breathing. It is enclosed, however, in layers of broad flat muscles whose fibers run in different directions, strengthening the abdominal wall on the same principle as the alternating layers of wood fibers in plywood (table 10. Three layers of muscle enclose the lumbar region and extend about halfway across the anterior abdomen (fig. The next deeper layer is the internal oblique muscle, whose fibers pass upward and anteriorly, roughly perpendicular to those of the external oblique. The deepest layer is the transverse abdominal muscle (transversus abdominis), with horizontal fibers. Anteriorly, a pair of vertical rectus abdominis muscles extends from sternum to pubis. These are divided into segments by three transverse tendinous intersections, giving them an appearance that body builders nickname the "six pack. At the rectus abdominis, they diverge and pass around its anterior and posterior sides, enclosing the muscle in a vertical sleeve called the rectus sheath. They meet again at a median line called the linea alba 50 between the rectus muscles. Another line, the linea semilunaris, 51 marks the lateral boundary where the rectus sheath meets the aponeurosis. On the anatomical right, the external oblique has been removed to expose the internal oblique and the pectoralis major has been removed to expose the pectoralis minor. On the anatomical left, the internal oblique has been cut to expose the transverse abdominal and the middle of the rectus abdominis has been cut out to expose the posterior rectus sheath. The rectus sheath has been removed on the anatomical left to expose the left rectus abdominis muscle. This extends obliquely from the anterior superior spine of the ilium to the pubis. The linea alba, linea semilunaris, and inguinal ligament are externally visible on a person with good muscle definition (see atlas B, fig. Weak points in the abdominal wall can be sites of inguinal and umbilical hernias (see Deeper Insight 10. The most prominent superficial back muscles are the latissimus dorsi and trapezius (fig. The most superficial muscles are shown on the left and the next deeper layer on the right. Deep to these is a prominent muscle, the erector spinae, which runs vertically for the entire length of the back from the cranium to the sacrum (fig. It is a thick muscle, easily palpated on each side of the vertebral column in the lumbar region. The most lateral of these is the iliocostalis, which from inferior to superior is divided into the iliocostalis lumborum, iliocostalis thoracis, and iliocostalis cervicis (lumbar, thoracic, and cervical regions). The next column medially is the longissimus, divided from inferior to superior into the longissimus thoracis, longissimus cervicis, and longissimus capitis (thoracic, cervical, and cephalic regions). The most medial column is the spinalis, divided into spinalis thoracis, spinalis cervicis, and spinalis capitis. The functions of all three columns are sufficiently similar that we will treat them collectively as the erector spinae. The major deep muscles are the semispinalis thoracis in the thoracic region and quadratus lumborum in the lumbar region (fig. The erector spinae and quadratus lumborum are enclosed in a fibrous sheath called the thoracolumbar fascia (fig. Extension and contralateral rotation of vertebral column Unilateral contraction causes ipsilateral flexion of lumbar spine; bilateral contraction extends lumbar spine. Standing up from such a position is therefore initiated by the hamstring muscles on the back of the thigh and the gluteus maximus of the buttocks. Standing too suddenly or improperly lifting a heavy weight, however, can strain the erector spinae, cause painful muscle spasms, tear tendons and ligaments of the lower back, and rupture intervertebral discs. This is why it is important, in heavy lifting, to crouch and use the powerful extensor muscles of the thighs and buttocks to lift the load. The multifidus is a collective name for a series of tiny muscles that connect adjacent vertebrae to each other from the cervical to lumbar region. Weakness in the pelvic floor can result in urinary or fecal incontinence or the prolapse (dropping) of internal organs between the thighs. The muscles and skeletal landmarks here are also of special importance in obstetrics. Viewed from within the pelvic cavity, its floor is formed mainly by an extensive muscle called the levator ani. Other than the vaginal canal, the sexes are nearly identical at this level, including the urogenital and anal triangles. In female, contractions constrict vaginal orifice and expel secretions of greater vestibular glands. The pelvic floor and perineum are penetrated by the anal canal, urethra, and vagina. The anterior half of the perineum is the urogenital triangle and the posterior half is the anal triangle. The urogenital triangle is divided into two muscle compartments separated by a strong fibrous perineal membrane. The muscle compartment between this membrane and the skin is called superficial perineal space, and the compartment between the perineal membrane and levator ani is the deep perineal space. We will examine these structures beginning inferiorly, just beneath the skin, and progressing superiorly to the pelvic floor. In females, this space also contains the clitoris; various glands and erectile tissues of the genitalia (see fig. In males, the bulbospongiosus (bulbocavernosus) muscles form a sheath around the root of the penis, and in females they enclose the vagina like a pair of parentheses. Cavernosus in these names refers to the spongy, cavernous structure of tissues in the penis and clitoris. These muscles may help to anchor the perineal body, but they are weakly developed and not always present, therefore not included in table 10. In the male fetus, each testis descends from the pelvic cavity into the scrotum by way of a passage called the inguinal canal through the muscles of the groin. A long pouch of peritoneum descends with the testis, but usually disappears by birth. Hernias occur in infants and children when this pouch persists, allowing a loop of intestine to enter it and appear near or in the scrotum (indirect hernia). Adult hernias may appear similar but are often due to a weakening of the inguinal canal (direct hernia). When the diaphragm and abdominal muscles contract, pressure in the abdominal cavity can soar to 1,500 pounds per square inch-more than 100 times the normal pressure and quite sufficient to produce an inguinal hernia, or "rupture. A hiatal hernia is a condition in which part of the stomach protrudes through the diaphragm into the thoracic cavity. It may cause heartburn due to the regurgitation of stomach acid into the esophagus, but most cases go undetected. A loop of small intestine has protruded through the inguinal canal into a space beneath the skin. The deep transverse perineal muscles anchor the perineal body on the median plane; the perineal body, in turn, anchors other pelvic muscles.

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When a hormone cannot enter a cell stages of hiv infection to aids buy starlix 120 mg without a prescription, it activates the formation of a/an inside the cell. It is often said, even in some textbooks, that mitochondria make energy for a cell. Kartagener syndrome is a hereditary disease in which dynein arms are lacking from the axonemes of cilia and flagella. S everal chapters in this book discuss hereditary traits such as blood types and hair color and genetic disorders such as color blindness, cystic fibrosis, diabetes mellitus, and hemophilia. By the late nineteenth century, biologists had observed chromosomes and their behavior during cell division. From that simple but insightful beginning, genetics has grown into a highly diverse science with several subdisciplines and is arguably the most dynamic of all natural sciences in these early decades of the twenty-first century. Cytogenetics uses the techniques of cytology and microscopy to study chromosomes and their relationship to hereditary traits. With improvements in the microscope, biologists of the late nineteenth century saw that cell division is immediately preceded by nuclear division, and during nuclear division, the chromosomes split neatly in two and distribute their halves to the two daughter cells. They came to suspect that the nucleus was the center of heredity and cellular control, and they began probing it for the biochemical secrets of heredity. A nucleotide consists of a sugar, a phosphate group, and a single- or double-ringed nitrogenous base (fig. The other two bases-adenine (A) and guanine (G)-have double rings and are classified as purines (fig. Each sidepiece is a backbone composed of phosphate groups alternating with the sugar deoxyribose. The bases face the inside of the helix and hold the two backbones together with hydrogen bonds. Adenine and thymine form two hydrogen bonds with each other, and guanine and cytosine form three, as shown in figure 4. The fact that one strand governs the base sequence of the other is called the law of complementary base pairing. It enables us to predict the base sequence of one strand if we know the sequence of the complementary strand. The events surrounding their discovery form one of the most dramatic stories of modern science-the subject of many books and at least one movie. When Watson and Crick came to share a laboratory at Cambridge University in 1951, both had barely begun their careers. Yet the two were about to become the most famous molecular biologists of the twentieth century, and the discovery that won them such acclaim came without a single laboratory experiment of their own. Watson said, "The instant I saw the picture my mouth fell open and my pulse began to race. The other 98% does not code for proteins, but apparently plays various roles in chromosome structure and regulation of gene activity. The chromatin then folds into successive zigzags, loops, and coils, getting thicker and shorter as it does so (fig. Finally, each chromosome is packed into its own spheroidal region of the nucleus, called a chromosome territory. A chromosome territory is permeated with channels that allow regulatory chemicals to have access to the genes. Whole chromosomes migrate to new territories as a cell develops-for example, moving from the edge to the core of a nucleus as its genes are activated for a certain developmental task, or back to the nuclear lamina to silence some genes. This allows genes on different chromosomes to partner with each other in bringing about developmental changes in the cell. It consists of two genetically identical, rodlike sister chromatids joined together at a pinched spot called the centromere. As much as biologists talk about genes, the term is devilishly difficult to define. For the purposes of this introductory book, however, we can settle for an approximate meaning. Some of these are gene-rich, such as chromosomes 17, 19, and 22, whereas others are gene-poor, such as 4, 8, 13, 18, 21, and the Y chromosome (see fig. Various combinations of these single-nucleotide polymorphisms2 account for all human genetic variation. Among the other fruits of this research, we now know the chromosomal locations of more than 1,400 disease-producing mutations. This information has opened the door to a branch of medical diagnosis and therapy called genomic medicine (see Deeper Insight 4. Genomics should also allow for earlier detection of diseases and for earlier, more effective clinical intervention. Drugs that are safe for most people can have serious side effects in others, owing to genetic variations in drug metabolism. Genomics has begun providing a basis for choosing the safest or most effective drugs and for adjusting dosages for different patients on the basis of their genetic makeup. Knowing the sites of disease-producing mutations expands the potential for gene-substitution therapy. This is a procedure in which cells are removed from a patient with a genetic disorder, supplied with a normal gene in place of the defective one, and reintroduced to the body. The hope is that these genetically modified cells will proliferate and provide the patient with a gene product that he or she was lacking- perhaps insulin for a patient with diabetes or a blood-clotting factor for a patient with hemophilia. Clinical applicability and safety were still under investigation and in early clinical trials as this textbook edition was written. Should an insurance company be entitled to know your genome before issuing health or life insurance to you so it can know your risk of contracting a catastrophic illness, adjust the cost of your coverage, or even deny coverage Should a prospective employer have the right to know your genome before offering employment These are areas in which biology, politics, and law converge to shape public policy. This is a striking illustration of how a great variety of complex structures can be made from a small variety of simpler components. The genetic code is a system that enables these 4 nucleotides to code for the amino acid sequences of all proteins. Computers store and transmit complex information, including pictures and sounds, in a binary code with only the symbols 1 and 0. Thus, it should not be surprising that a mere 20 amino acids can be represented by a code of 4 nucleotides; all this requires is to combine these symbols in varied ways. You can see from the table that sometimes two or more codons represent the same amino acid. Four symbols (N) taken three at a time (x) can be combined in Nx different ways; that is, there are 43 = 64 possible codons available to represent the 20 amino acids. Before studying the details, however, it will be helpful to consider the big picture. However, different genes are activated in different cells; for example, genes for digestive enzymes are active in stomach cells but not in muscle cells. Any given cell uses only one-third to two-thirds of its genes; the rest remain dormant in that cell, but may be functional in other types of cells. Most translation occurs in the cytoplasm, but 10% to 15% of proteins may be synthesized in the nucleus, with both steps occurring there. At the end of the gene is a base sequence that serves as a terminator, which signals the polymerase to stop. This molecule contains segments called exons that will be translated into a protein, and segments called introns that are removed before translation. Through a mechanism called alternative splicing, one gene can code for more than one protein. This is a partial explanation of how the body can produce millions of different proteins with little more than 22,000 genes.

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During each moment of depolarization hiv infection diagram purchase 120mg starlix mastercard, a hair cell releases a burst of neurotransmitter from its base, exciting the sensory dendrite that synapses with the hair cell. To summarize: Each upward movement of the basilar membrane pushes the inner hair cells closer to the stationary tectorial membrane. Each stereocilium has a tip link connecting it to an ion channel at the top of the next shorter stereocilium. The hair cell releases a burst of neurotransmitter, exciting the sensory processes of the cochlear nerve cells below it. Sensory Coding For sounds to carry any meaning, we must distinguish differences in loudness and pitch. Our ability to do so stems from the fact that the cochlea responds differently to sounds of different amplitude and frequency. Variations in loudness (amplitude) cause variations in the intensity of cochlear vibration. A soft sound produces relatively slight up-and-down movements of the basilar membrane. Hair cells are stimulated only moderately, and a given sound frequency stimulates hair cells in a relatively limited, or focused, region of the cochlea. Hair cells respond more intensely, generating a higher firing frequency in the cochlear nerve. In addition, for a given frequency, a loud sound vibrates a longer segment of the basilar membrane and thus excites a greater number of hair cells. If the brain detects moderate firing rates associated with hair cells in relatively narrow bands of the cochlea, it interprets this as a soft sound. If it detects a high firing frequency in nerve fibers associated with broader bands, it interprets this as a louder sound. At its distal end (the apex of the cochlea), it is unattached, five times wider, and more flexible. Think of the basilar membrane as analogous to a wire stretched tightly between two posts. If you pluck the wire at one end, a wave of vibration travels down its length and back. This produces a standing wave, with some regions of the wire vertically displaced more than others. The peak amplitude of this wave is near the distal end in the case of low-frequency sounds and nearer the proximal end with sounds of higher frequencies. When the brain receives signals mainly from inner hair cells at the distal end, it interprets the sound as low-pitched; when signals come mainly from the proximal end, it interprets the sound as high-pitched (fig. This results in some regions of the cochlea sending fewer signals to the brain than neighboring regions, so the brain can better distinguish between sound frequencies. The efferent fibers can inhibit the sensory fibers from firing in some areas of the cochlea, and thus enhance the contrast between signals from the more responsive and less responsive regions. The Auditory Projection Pathway the sensory nerve fibers beginning at the bases of the hair cells belong to bipolar sensory neurons. Conductive deafness results from any condition that interferes with the transmission of vibrations to the inner ear. Such conditions include a damaged tympanic membrane, otitis media, blockage of the auditory canal, and otosclerosis. Otosclerosis27 is fusion of the auditory ossicles to each other or fusion of the stapes to the oval window. Sensorineural (nerve) deafness results from the death of hair cells or any of the nervous elements concerned with hearing. It is a common occupational disease of factory and construction workers, musicians, and other people exposed to frequent or sustained loud sounds. Deafness leads some people to develop delusions of being talked about, disparaged, or cheated. Cochlear Tuning Just as we tune a radio to receive a certain frequency, we also tune our cochlea to receive some frequencies better than others. The peak amplitude of the wave varies with the frequency of the sound, as shown here. The amount of vibration is greatly exaggerated in this diagram to clarify the standing wave. The superior olivary nucleus also functions in binaural28 hearing- comparing signals from the right and left ears to identify the direction from which a sound is coming. Other fibers from the cochlear nuclei ascend to the inferior colliculi of the midbrain. Fourth-order neurons complete the pathway from there to the primary auditory cortex; thus the auditory pathway, unlike most other sensory pathways, involves not three but four neurons from receptor to cerebral cortex. The primary auditory cortex lies in the superior margin of the temporal lobe and extends deeply into the lateral sulcus (see fig. Only later did vertebrates evolve the cochlea, outer- and middle-ear structures, and auditory function of the ear. In humans, the receptors for equilibrium constitute the vestibular apparatus, which consists of three semicircular ducts and two chambers- an anterior saccule29 and a posterior utricle30 (see fig. There are two kinds of acceleration: (1) linear acceleration, a change in velocity in a straight line, as when riding in a car or elevator; and (2) angular acceleration, a change in the rate of rotation, as when your car turns a corner or you swivel in a rotating chair. The saccule and utricle are responsible for static equilibrium and the sense of linear acceleration; the semicircular ducts detect only angular acceleration. With the head erect, the otolithic membrane bears directly down on the hair cells, and stimulation is minimal. When you tilt your head down to read a book, however, the heavy otolithic membrane sags and bends the stereocilia, stimulating the hair cells. Any orientation of the head causes a combination of stimulation to the utricules and saccules of the two ears. The inertia of the otolithic membranes is especially important in detecting linear acceleration. The membrane of the macula utriculi briefly lags behind the rest of the tissues, bends the stereocilia backward, and stimulates the cells. When you stop at the next light, the macula stops but the otolithic membrane keeps going for a moment, bending the stereocilia forward. The hair cells convert this stimulation to nerve signals, and the brain is thus advised of changes in your linear velocity. The macula sacculi is nearly vertical and its hair cells therefore respond to vertical acceleration and deceleration. When the elevator stops, the membrane keeps going for a moment and bends the hairs upward. In both cases, the hair cells are stimulated and the brain is made aware of your vertical movements. These sensations are important in such ordinary actions as sitting down, and as your head bobs up and down during walking and running. The Semicircular Ducts the head also experiences rotary movements, such as when you spin in a rotating chair, walk down a hall and turn a corner, or bend forward to pick something up from the floor. The anterior and posterior semicircular ducts are oriented vertically at right angles to each other. The orientation of the ducts causes a different duct to be stimulated by rotation of the head in different planes. Each one opens into the utricle and has a dilated sac at one end called the ampulla. The hair cells have stereocilia and a kinocilium embedded in the cupula,36 a gelatinous cap that extends from the crista to the roof of the ampulla. After 25 to 30 seconds of continual rotation, however, the endolymph catches up with the movement of the duct and stimulation of the hair cells ceases. Projection Pathways Hair cells of the macula sacculi, macula utriculi, and semicircular ducts synapse at their bases with sensory fibers of the vestibular nerve. Fibers of the vestibular apparatus lead to a complex of four vestibular nuclei on each side of the pons and medulla. Nuclei on the right and left sides of the brainstem communicate extensively with each other, so each receives input from both the right and left ears.