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Compliance the elastic recoil of the lung blood pressure 15090 buy 50mg tenormin amex, which is measured under static condition is called compliance. The compliance is defined as the volume change per unit transpulmonary pressure difference between the esophageal or intrapleural pressure and the mouth pressure. The compliance measures the relative stiffness and distensibility of the lungs and thorax. About 150 mL of this volume fills the airways from the nose and mouth down to the respiratory bronchioles and this Chapter 114: Pulmonary Function Tests 967 change is higher than normal, the tissues are more distensible and if it is less then the tissue are stiffer than normal. The patients with decreased compliance put more respiratory effort to achieve adequate alveolar ventilation and therefore they are dyspneic. Airway Resistance this represents the frictional resistance to airflow through the conducting air passages. The patients with increased airway resistance often present serious mechanical problems and develop dyspnea. The measurement of the following respiratory parameters gives a fair idea of the mechanics of breathing in clinical practice. This test measures the vital capacity in relation to time and gives the portion of the vital capacity expired in a specified time, say one, two or three seconds. In normal conditions, 80 to 85% of the forced vital capacity is expired in the first second, 95% in two seconds and 97% in three seconds (Refer. Measurement of Ventilatory Functions Most of the pulmonary functions are measured by spirometry. In the space between the two walls is placed an inverted hollow cylindrical bell of 9 liters capacity. The bell is attached to a counterbalance with a chain, which passes over a pulley. Abnormalities of Ventilation There are two major patterns of ventilatory abnormalities: restrictive and obstructive patterns. The restrictive diseases can be broadly subdivided in to parenchymal and extraparenchymal disease. Extraparenchymal dysfunction is again of two categories, the extraparenchymal dysfunction in inspiration and the extraparenchymal dysfunction in inspiration plus expiration. Alterations in Lung Volumes and Capacities Lung volumes and capacities show a wide range in the normal population depending on the age, sex, and height of the subject. Indian population shows significant lower values as compared to their western counter parts. Deviation up to 20% from the predicted value for a given age, sex, and height is commonly seen in normal subjects. However, in a particular individual, even 5% change from his preexisting value may be of significance. Therefore, serial measurement of these values is of great importance in diagnosis. Loss of functioning lung tissue - Interstitial pulmonary fibrosis - Chest deformity - Neuromuscular disease - Thickened pleura 2. Loss of distensibility of lung tissues or pleura - Atelectasis - Consolidation - Pulmonary edema - Pulmonary resection Restrictive Extraparenchymal Dysfunction Inspiratory dysfunction: In extraparenchymal inspiratory dysfunction, which occurs usually due to either inspiratory muscle weakness or a stiff chest wall, the adequate distending forces are prevented from being exerted on an otherwise normal lung. Neuromuscular diseases Myasthenia gravis Paralysis of diaphragm Muscular dystrophy Conditions that Decrease Static Lung Compliance Pulmonary edema Chronic pulmonary congestion Kyphoscoliosis Fibrothorax Interstitial fibrosis Atelectasis Patients with decreased compliance have to put in more respiratory muscular effort to achieve adequate alveolar ventilation. Conditions that Increase Airway Resistance Bronchial asthma Chronic bronchitis Emphysema Other diseases that are characterized by airway obstruction. Patients with increased airway resistance are usually dyspneic, which depends on severity of airway obstruction. As it is effort dependent it should be performed properly to get the appropriate result. But greater degree of non-uniform perfusion occurs in diseases like pulmonary embolism and diseases that destroy lung tissues. The arterial blood gas tension is primarily affected by the relationship of ventilation with perfusion. Diffusion Diffusion is the physical process by which gas move across a membrane from the region of higher partial pressure to the region of lower partial pressure. In lungs, oxygen moves from alveoli to the pulmonary capillaries to combine with the hemoglobin. Measurement of the arterial blood gas tension is essential in the evaluation of pulmonary functions. Shunting (when desaturated blood effectively bypasses oxygenation at alveolar-capillary level): it is common in cyanotic congenital heart disease. However, the value can be fallacious if the patient does not cooperate or fails to use maximum effort to carry out the test. In erect posture, resting ventilation per unit volume of lung is greater at the bases than at the apices. In disease states, the distribution becomes more uneven resulting in hypo- and hyperventilated areas. Such non-uniform distribution of inspired gas leads to decreased oxygen tension in the arterial blood. The uniformity of distribution of inspired air is measured by nitrogen washout method. An alveolar gas sample after 7 minutes of breathing oxygen normally contains less than 2. The higher the percentage of nitrogen in the alveolar sample, the greater is the degree of non-uniformity of distribution of inspired gas. The normal ratio of ventilation to Conditions that Decrease Pulmonary Diffusing Capacity 1. When the total surface area of the alveolar capillary membrane is reduced - Emphysema - Pulmonary embolism - Thrombosis of pulmonary capillaries - Following surgical removal of lung tissues 2. When there is defect in the alveolar-capillary membrane (thickening of the membrane) - Asbestosis - Sarcoidosis - Progressive systemic sclerosis - Collagen diseases - Interstitial edema - Interstitial fibrosis - Diffuse metastatic lesions of the lung Increase in Pulmonary Diffusing Capacity 1. Exercise 970 Section 10: Respiratory System Gas Sampling and Analysis Sampling of Alveolar Air Sampling of alveolar air is performed by two methods: 1. Haldane-priestley method: the subject makes a forced expiration through a long narrow tube of about 3 feet length and 2. A sample of air contained near the mouthpiece of the tube is withdrawn via a side tube into a sampling tube. Breathing through a mouthpiece fitted with inspiratory and expiratory valves collects a sample of the end-tidal volume. Measurement of pressures, vascular resistance, blood volume and distribution of blood flow in the pulmonary and systemic circuits help in detecting venoarterial shunt, vascular occlusion and decreased pulmonary capillary volume. The vessels are comparatively thin-walled and provide less resistance to flow in comparison to systemic vessels. In upright posture, the arterial pressure is lowest at the apex and highest at the lung bases. Assessment of Pulmonary Blood Flow Assessment of pulmonary circulation depends upon measuring pulmonary vascular pressures and cardiac output. These measurements are usually done in intensive care units with the facilities of invasive monitoring. With a flow-directed pulmonary arterial (Swan-Ganz) catheter, the pulmonary arterial and pulmonary capillary wedge pressures can be measured directly. A two-way valve is fixed to the Douglas bag and then connected to the mouth of the subject. Respiratory Gas Analysis Samples of inspired air (atmospheric), mixed expired air (from the Douglas bag) and alveolar air (collected by Haldane-Priestly method) are taken for analysis of partial pressure of oxygen, carbon dioxide and nitrogen. The oxygen carrying capacity of the blood is estimated by Van Slyke gasometric method. The partial pressure of carbon dioxide is also determined with the help of gasometers.

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Nondisjunction of Chromosome Nondisjunction of chromosome 21 (an autosome) is not uncommon blood pressure guidelines 2014 purchase tenormin pills in toronto. Female Pseudohermaphroditisms Male external genital development occurs in genetic females exposed to androgen during 8th to 13th week of gestation. Source of androgen is usually congenital virilizing adrenal hyperplasia of fetus or virilizing ovarian tumor of the mother. Sometimes it may be iatrogenically-induced following treatment of mother with androgens or progestational drugs. In a typical female pseudohermaphrodite, the individual possesses ovaries, oviducts, but there is varying degrees of masculine differentiation of external genitalia. Male Pseudohermaphroditisms Development of female external genitalia in a genetic male is called male pseudohermaphroditism. Male pseudohermaphroditism could also be due to androgen resistance that usually occurs in deficiency of 5-reductase, the enzyme that forms dehydroepiandrosterone or due to defects in androgen receptors. Developmental Abnormalities the developmental abnormalities are mainly hormonal disorders. The hormonal abnormalities are broadly divided into pseudohermaphroditisms (both female and male patterns) and enzyme deficiencies. Pseudohermaphroditisms A pseudohermaphrodite is an individual with genetic constitution and gonad of one sex, but the external genitalia of the other sex. In these conditions, the patients have normal gonadal development in accordance with their chromosomal sex, but afterward they develop heterosexual characteristics due to opposite hormonal excess. Enzyme Deficiencies Congenital 17-hydroxylase deficiency causes male pseudohermaphroditism. How the genetic sex is determined in males and females, How the gonadal sex is determined in males and females, How the phenotypic (genital) sex is determined in males and females, What is called a genetic male and a genetic female Appreciate the physiological basis of causation of precocious puberty and delayed puberty. Describe the mechanism of onset of puberty, and physiological basis of changes at puberty. In females, reproducibility totally stops at menopause, whereas in males reproducibility continues. Age and Initiating Stimulus Age of Onset of Puberty the age of onset of puberty varies depending on various factors like socioeconomic and environmental conditions and genetic constitutions. In general, in developed countries, puberty occurs earlier than in the developing countries. During this period, the hypothalamic-pituitary-gonadal axis is activated to bring the gametogenic functions of the gonads to their threshold of reproductive maturation. Under the influence of gonadotropins secreted from pituitary, maturation of gonads occurs that in turn helps in maturation of the reproductive system. During this period, the endocrine and gametogenic functions of the gonads first develop to the point where the reproduction becomes possible. Initiating Stimulus the increased secretion of adrenal androgen, called adrenarche, occurs about 1 to 2 years before the onset of puberty. This increased adrenal androgen is believed to stimulate the production of gonadal hormones that cause maturation of reproductive organs. Chapter 66: Physiology of Puberty and Menopause 585 Stages of Puberty In Boys the pubertal development in males occurs in five stages (by Tanner method, modified). Though this occurs due to the secretion of adrenal androgen (adrenarche), testicular androgen also contributes. Dehydroepiandrosterone secreted from adrenal gland plays some role in the maturation of hypothalamic neurons. The adipose tissue via secretion of leptin also plays some role in the determination of the time of onset of puberty (see below). Ejaculation of sperm occurs either in dreams, or on masturbation or by sexual act. In Girls the pubertal development in females also described in five stages (by Tanner method, modified). Role of Leptin It has been observed that body weight increases to a critical level before the onset of puberty, especially in females. It is also observed that the onset of puberty is delayed in girls with lower body weight. Leptin, the hormone secreted from adipose tissue cell is believed to help in the maturation of hypothalamogonadal axis. This is supported by the experimental evidence that injection of leptin in female mice results in precocious puberty. Puberty may be delayed in spite of presence of normal gonads, which is called eunuchoidism in males and primary amenorrhea in girls. Precocious Puberty Precocious puberty may be of two types: true precocious puberty and precocious pseudopuberty. The functions of gonads slowly decrease finally resulting in complete cessation of menstrual cycle. True Precocious Puberty Early development of secondary sexual characteristics, may be associated with premature development of gonads is known as true precocious puberty. This occurs due to early pubertal pattern of secretion of gonadotropin from pituitary. Gonadotropin independent precocity: Precocious gametogenesis without increase in gonadotropin secretion. Constitutional precocity: When the actual cause of precocity can not be ascertained. Mechanism and Features Mechanism of Menopause the mechanism and purpose of menopause are not clear. The female gonads progressively become unresponsive to gonadotropins with advancing age. In males, though there is some decline in reproductive capacity from 5th decade of life, climacteric does not occur. Precocious Pseudopuberty the development of secondary sexual characteristics without gametogenesis is called as precocious pseudopuberty. This occurs due to exposure of immature males to abnormal quantity of androgen, and in immature females the abnormal exposure to estrogen. Adrenal causes: Congenital virilizing adrenal hyperplasia can lead to precocious pseudopuberty. Androgen secreting or estrogen secreting tumors of adrenal gland resulting in precocious pseudopuberty are not uncommon. Gonadal causes: Leydig cell tumor of testis in male or granulosa cell tumor of ovary in females can cause precocious pseudopuberty. Features of Menopause Hot flushes (sensation of warmth spreading from trunk to the face) occur frequently. Delayed Puberty When onset of puberty is delayed beyond the age of 17 in girls and 20 in boys, the condition is called delayed puberty. It occurs usually due to panhypopituitarism that causes failure of maturation of gonads. Management of Menopause the fear that the women will lose her womanhood may cause psychological depression. It needs proper care, counseling and assurance of the spouse to make her understand and adjust to this physiological phenomenon of the nature. However, metabolic and other complications of estrogen should be kept in mind while continuing estrogen therapy for a longer period. Increased secretion of adrenal androgens (adrenarche) sensitizes hypothalamo-pituitary-gonadal axis for pubertal changes. Reproducibility totally stops at menopause, whereas in males reproducibility continues. Precocious puberty, Stages of puberty in boys and girls, Mechanism of onset of puberty, Mechanism, features and management of menopause may be asked as Short Questions in exam. Define puberty, What is the age of onset of puberty in boys and girls, What are the stages of puberty in boys, What are the stages of puberty in girls, Explain the mechanism of onset of puberty, What is true precocious puberty and what are its causes, What is precocious pseudopuberty and what are its causes, What is delayed puberty, What is menopause, What is the mechanism of menopause, What is the age of menopause, What are the features of menopause, How menopause can be managed. Name the different parts of male reproductive system, and give the functions of each.

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Moreover arrhythmia when sleeping cheap tenormin 100 mg amex, hyperlipi demic complications such as coronary artery disease are common in hypothyroidism. Thyroid Scintiscanning Scintiscanning offers a visual display of the size and shape of the thyroid gland. The functional activity of the thyroid nodules (hot or cold nodules) (hot or cold nodules) can be evaluated. In the investigation of masses in the neck or mediastinum, scintiscanning is useful to detect their nature. Originally 131I was used for visualizing the thyroid, the scan being done after 24 hours of administration. At present technetium pertechnetate, which has a half life of 6 hours is used for this purpose. With technetium scanning it can be done soon after the injection of the radioisotope. An exaggerated response is observed in primary hypothyroidism because the negative feedback effect of T4 is reduced. False negative results occur Chapter 57: Thyroid Gland 497 more frequently than false positive ones. Achilles Tendon Reflex Decreased relaxation time of Achilles tendon reflex is an important clinical assessment to suspect hypothyroi dism. Therefore, thyroxine deficiency if present in newborn, should be detected and treated immediately after birth. Therefore, heat intolerance and tachycardia even during sleep (sleeping tachycardia) are highly indicative of hyperthyroidism. In examination, Steps of thyroid hormone synthesis, mechanism of action and physiological actions of thyroid hormone, is usually asked as a Long Question. Apply the knowledge of understanding metabolism of catecholamines in diagnosing the excess or deficiency of catecholamines. Give the differences between the functions of epinephrine and norepinephrine, especially their cardiovascular effects. Learn the physiological basis of features, diagnosis, and treatment of pheochromocytoma. Describe the synthesis, secretion, and regulation of secretion of adrenomedullary hormones. The adrenals consist of two distinct endocrine glands, one surrounding the other: the inner adrenal medulla, surrounded by the outer adrenal cortex that consists of three layers. Adrenal medulla develops from neuroectodermal tissue related to sympathetic ganglia, and therefore secretes catecholamines. The gland is highly vascular and receives blood from three sources: branches of aorta, renal arteries, and phrenic arteries. The arterial blood enters the sinusoidal capillaries in the cortex and then drains into the medullary venules. This arrangement exposes the medulla to the high concentration of corticosteroids secreted from the cortex. In general, they play important role in following physiological processes of the body: 1. Though, adrenomedullary hormones are not essential for immediate survival, they help prepare the individual to deal with emergencies. His outstanding works on the blood pressure-raising constituents of the adrenal medulla led to the identification and synthesis of catecholamines, and further to the development of many derivatives of catecholamines. Essentially, adrenal medulla represents an enlarged and specialized sympathetic ganglion in which the postganglionic fibers are embedded and modified to become the endocrine cells. The gland consists of clumps and strands of chromaffin cells, interspersed with venous sinuses. The cells are called chromaffin cells as they have greater affinity for chromium stains. They contain numerous granules that are present in the vesicles that store catecholamines. There are two types of endocrine cells in the adrenal medulla: epinephrine-secreting and norepinephrinesecreting, 1. Epinephrine-secreting type: In humans, 90% of cell types in adrenal medulla are epinephrine-secreting type. Norepinephrine-secreting type: They constitute 10% of the cell mass of adrenal medulla. The types of cells that secrete dopamine are not known, but are believed to be very less in number. Chromaffin cells receive sympathetic preganglionic cholinergic innervation and on stimulation discharge their content into venous sinuses. The granules containing hormone is discharged into extracellular space by exocytosis and from there the hormone enters sinusoidal vein. In addition to secretion of catecholamines, the gland also secretes following peptides: 1. Conversion of tyrosine to Dopa is catalyzed by tyrosine hydroxylase and dopa to dopamine by dopa decarboxylase. After synthesis, the hormones are stored in the granules of chromaffin cells before they are secreted into venous blood. It may be noted that, the concentration of glucocorticoids is normally high in blood bathing adrenal medulla as blood from cortex drains into medulla before entering general circulation. Effect of Sympathetic Stimulation Adrenal medulla is stimulated with the activation of sympathetic system. Therefore, sympathetic stimulation not only increases norepinephrine secretion from its nerve endings that slowly enters circulation, but also directly increases epinephrine secretion from adrenal medulla that rapidly enters circulation. Thus, sympathetic activation increases the level of both epinephrine and norepinephrine in blood. Effects of 21b-hydroxylase During fetal life, the adrenocortical enzyme, 21b-hydroxylase stimulates development of adrenal medulla. Therefore, fetal deficiency of 21b-hydroxylase results in dysplasia of adrenal medulla, and if enzyme deficiency is not corrected promptly after birth, circulating catecholamines remain permanently low. Synthesis, Secretion, and Metabolism of Catecholamines Synthesis and Secretion Catecholamines are synthesized from the amino acid phenylalanine and tyrosine (Flowchart 58. Regulation of Secretion Catecholamine secretion from adrenal medulla increases in following conditions. Trauma (Physical injury) Chapter 58: Adrenal Gland: the Adrenal Medulla Flowcharts 58. Degradation the steps of degradation of epinephrine and norepinephrine are summarized in Flowcharts 58. Therefore, the activity of adrenal medulla is assessed primarily by measurement of plasma epinephrine or free urinary epinephrine. Cold the main mechanism of secretion in these conditions is sympathetic stimulation. They stimulate the neural pathways that activate sympathetic fibers to release norepinephrine and adrenal medulla to release mainly epinephrine. The circulating epinephrine is mainly derived from adrenal medulla and norepinephrine from the sympathetic nerve endings, whereas dopamine is derived equally from adrenal medulla and autonomic nerve endings. About 70% norepinephrine and epinephrine, and 90% of dopamine are conjugated to sulfate. Metabolism of epinephrine forms metanephrine and norepinephrine forms normetanephrine. There are three types of b receptors: b1, b2, and b3, and two types of a receptors: a1 and a2.

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Appreciate the internal neuronal arrangements and their functions within the cerebellum blood pressure chart american medical association safe 50 mg tenormin. It receives special sensory inputs from visual, auditory and vestibular structures. It projects to almost all areas of brain that are involved in control of motor activities. Thus, cerebellum plays a critical role in motor control by integrating sensory and motor information in the brain. Therefore, cerebellum strongly influences all aspects of movement, starting from the rate, range, force, and direction to the termination of movement. Cerebellum directly projects to the brainstem nuclei that give rise to major descending pathways. He is also popular for describing the Purkinje fibers in the ventricle of heart and Purkinje images in the eyes. It is connected to midbrain through superior cere bellar peduncle, to pons through middle cerebellar peduncle and to the medulla through inferior cerebe llar peduncle. Vestibulocerebellum this is also called archicerebellum, as phylogenetically it is the oldest part. This part of cerebellum is called vestibulocerebellum for its extensive and reciprocal connection with the vestibular nuclei. It is concerned with equilibrium and learning induced changes in vestibuloocular reflex. The surface area of cerebellum is about 75% of the cerebral cortex, but in weight it is only 10% of the cortex. There are two main fissures in the cerebellum that divide it into two major parts: the posterolateral fissure that separates flocculonodular lobe from rest of the cerebellum and the primary fissure that separates the anterior lobe from the posterior lobe. Functional Divisions and Functions of Cerebellum Functionally, cerebellum is divided into three major subdi visions: vestibulocerebellum, spinocerebellum and cerebrocerebellum. It is called spinocerebellum, as it receives proprioceptive and other sensory inputs from all the body parts through the spinal cord. It also receives inputs from the motor cortex, where motor planning is carried out. The vermal portion of spinocerebellum projects to the brainstem areas that control axial and proximal limb muscles. The paravermal region of spinocerebellum projects to the brainstem nuclei that influence distal limb muscles. Note the outer molecular layer, middle Purkinje cell (P) layer and inner granular layer. Cerebrocerebellum this is also called neocerebellum, as it is newest phylogenetically. Cortex projects to neocerebellum via the pontine nuclei; hence, this is also called corticopontocere bellum. As it interacts with the cortex, it is involved in planning and programming of the movements. The axons of the interneurons of the molecular layer project to the dendrites of the Purkinje cells. Purkinje cells are the only cells that project form the cortex of cerebellum to the deep cerebellar nuclei. Thus, Purkinje cells are connecting links between cerebellar cortex and deep cerebellar nuclei. Granular Cell Layer this layer contains granule cells and Golgi cells (interneurons). The granule cells receive inputs from the mossy fibers and project to the Purkinje cells, basket cells, stellate cells and Golgi cells via parallel fibers. Functional Histology Cerebellum is divided into the outer cortex and the inner part containing deep cerebellar nuclei. Cerebellar Cortex the cerebellar cortex has three layers: outer molecular layer, middle Purkinje cell layer, and inner granular layer. Molecular Layer this layer contains interneurons that are basket cells and stellate cells. Nucleus Fastigius the nucleus fastigius is present in the deep vermal por tion of the cerebellum. Nucleus Globosus and Nucleus Emboliformis the globos and emboliform nuclei are combinely known as nucleus interpositus. Chapter 132: Cerebellum 1091 Nucleus Dentatus this is present in the hemispheric portion of the cere bellum. The deep cerebellar nuclei project to the different parts of the brainstem and thalamus (discussed in Cere bellar Outputs). Cerebellar Connections Cerebellar Inputs Cerebellum receives somatosensory inputs from almost all parts of the body and inputs of all sensory modalities including special sensory inputs. Vestibulocerebellar tract: Through this tract, cerebellum receives impulses directly from the vestibular apparatus and also from the vestibular nuclei. Dorsal spinocerebellar tract: this tract conveys proprioceptive and exteroceptive impulses from different parts of the body to cerebellum 3. Ventral spinocerebellar tract: this pathway also conveys proprioceptive and exteroceptive impulses from different parts of the body. Cuneocerebellar tract: this tract originates from lat eral cuneate nucleus in the caudal medulla and conveys proprioceptive inputs from head and neck. Tectocerebellar tract: this tract conveys visual infor mation from superior colliculus and auditory infor mation from inferior colliculus to the cerebellum. Pontocerebellar tract: Impulses from motor cortex reach cerebellum via pontine nuclei. Olivocerebellar tract: Proprioceptive inputs from the whole body reaches cerebellum via inferior olive. Inferior olivary nucleus is located in the rostral medulla that receives input from the vestibular system, spinal cord and cerebral cortex. Mode of Inputs Inputs to cerebellum reach via three routes: mossy fibers, climbing fibers and other inputs (Table 132. These fibers carry direct proprio ceptive inputs from all parts of the body and also convey input from cerebral cortex. Climbing Fiber Inputs: Climbing fibers convey inputs from inferior olivary nucleus to cerebellum. Other Inputs: Cerebellum receives monoaminergic inputs, and inputs from thalamus and other parts of the brain. Thalamic and other inputs From nucleus raphe magnus From nucleus locus ceruleus From thalamus and other brain areas Nature of input Proprioceptive inputs from whole body via relay in inferior olivary nucleus Proprioceptive and exteroceptive inputs Proprioceptive and exteroceptive inputs Inputs from vestibular nuclei Visual information from superior colliculus and auditory inputs from inferior colliculus Proprioceptive inputs from head and neck Inputs from cortex via pontine nuclei 1092 Section 11: Neurophysiology. Cerebellar Outputs Different parts of cerebellum project to various descending pathways via deep cerebellar nuclei. Output from Cerebrocerebellum the cerebellar hemisphere projects to the dentate nucleus, which, in turn, project to the motor cortex via thalamus. As different parts of the cerebellum project to all the motor nuclei in the brainstem and to the motor cortex, cerebellum controls activities of all the descending path ways (corticospinal and extrapyramidal systems). Therefore, diseases of the cerebellum affect both regulation of posture and skilled voluntary movements. Output from Vestibulocerebellum Vestibulocerebellum directly projects to the vestibular nuclei without any relay in the deep cerebellar nuclei. Thus, vestibulocerebellum directly controls vestibulo spinal tract activity Output from Spinocerebellum 1. The vermal portion of the spinocerebellum projects to fastigial nucleus, which, in turn, projects to pontine reticular formation and vestibular nuclei in the brainstem. Thus, vermal part of spinocerebellum controls the activity of pontine reticulospinal tract and vestib ulospinal tract. The paravermal portion of the spinocerebellum projects to the nucleus interpositus, which, in turn, projects to the red nucleus. Thus, paravermal part of the spinocerebellum controls the activity of rubrospi nal tract. Internal Connections of Cerebellum Cerebellum receives inputs from two sources: the climb ing fibers (from olivary nucleus), and the mossy fibers.

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In ventricular muscles and Purkinje fibers 1 buy 50 mg tenormin overnight delivery, this channel also hyperpolarizes the membrane during phase 4. As soon as the membrane potential reaches threshold, rapid depolarization (a steep rise in the spike) occurs. This is due to sudden increase in the permeability of the membrane to sodium ions, which occurs due to hun dredfold opening of voltagegated sodium channels. In fact, immediately above the threshold level of the membrane potential, initially activated sodium chan nels activate other sodium channels (autoactivation) that results in manifold opening of the channels. This phase of partial repolarization is due to closure of sodium channels (cessation of sodium influx). Opening of outward transient rectifying K+ channel that causes transient outflux of K+ also partly contrib utes. A Phase 2 this is known as plateau phase as the action potential in this phase remains in a state of sustained depolarization. This phase is due to sustained increased permeabil ity of the membrane to calcium ions (through slowly opening calcium channels) that results in slow calcium influx, which occurs due to slower but prolonged opening of voltagegated calcium channels. The plateau phase is of much lesser duration in atrial muscle than the ventricular muscles. This occurs due to cessation of calcium influx (closure of calcium channels) and increased membrane per meability to potassium (increased potassium efflux). Phase 0: Phase of depolarization; Phase 3: Phase of repolarization; and Phase 4: Phase of slow depolarization to threshold. Phase 3 this phase is due to closure of calcium channels and opening of the potassium channels (increased potassium efflux). The relative increase in permeability to K+ drives the membrane potential towards the equilibrium potential. The early part of this phase is due to the closure of potassium channels (decreased potassium conduct ance). Calcium sparks (release of calcium locally from sarcoplasmic reticulum) also con tributes. The automaticity (the ability of the pacemaker to produce its own impulse) is possible due to spontaneous diastolic depolarization of the membrane potential following completion of each action potential. The resting (diastolic) membrane potential that depolar izes is called as the prepotential as it brings the membrane potential to the threshold level, which then triggers the action potential. Phases and Ionic Basis Slow response action potential consists mainly of three components. The depolarization is mainly due to influx of calcium ions through the long acting calcium channels (Lcal cium channels). Ionic Basis Ionic basis of pacemaker potential has two important parts: the ionic basis at initial part and at the later part of the potential. In the Initial Part the repolarization phase of the action potential in the nodal tissues is due to efflux of potassium ions. Toward the end of repolarization, the Ik declines, which is known as potassium decay. The entry of calcium through the T-channels com pletes the pacemaker potential and takes the mem brane potential to the threshold level, which then fires to form the action potential. Other Ions Recently it has been suggested that the calcium sparks (release of calcium locally from sarcoplasmic reticulum) also contribute to the pacemaker potential. Thus, the pacemaker potential is largely due to decay of the potassium efflux and Ih (the initial part), and influx of calcium (the later part). Membrane potential is restless: Actually, it is the rest ing membrane potential that automatically depolarizes to form the pacemaker potential. Thus, in pacemaking this sues there is no resting membrane potential, rather the pacemaker potential is the restless membrane potential. The sympathetic stimulation makes the slope steeper and increases the heart rate, whereas the parasympathetic stimulation makes the slope flat and decreases the heart rate. These effects on heart rate are mainly due to their influence on the slope of pacemaker potential. Note that sympathetic stimulation increases heart rate by rapidly raising the pacemaker potential so that the slope of prepotential reaches threshold earlier. Parasympathetic stimulation decreases heart rate by slowly raising the pacemaker potential so that slope of prepotential reaches threshold later. Also, parasympathetic stimulation causes hyperpolarization (makes the membrane potential more negative) so that prepotential takes more time to reach threshold from a more negative value. It counters the decay of K+ and hyperpolarizes the membrane during phase 4 that slows the pacemaker potential. This decreases calcium influx via Ttype cal cium channels that decreases the slope of prepotential and takes the membrane potential away from thresh old level. The decrease in intracellular calcium concentration also decreases the force of contraction. However, vagal stimulation mainly affects the rate rather than the force of contraction, because ventricles have sparse vagal innervation. Effect of Vagal Stimulation the vagal stimulation to the heart decreases the heart rate. The heart rate decreases because the membrane is hyperpolarized and the slope of prepotential is decreased (becomes relatively flat). This occurs due to release of ace tylcholine (Ach) from the parasympathetic nerve endings, which increases the potassium conductance and delays the potassium decay. The slope of prepotential becomes steeper, so that the threshold level is reached earlier than the normal, which increases the heart rate. The membrane is rapidly depolarized to the firing level and the depolarization phase of the action potential becomes steeper. The increase in intracellular calcium ion in the ventric ular myocytes increases the force of contraction. However, impulse from atrial muscle cannot directly excite the ventricular muscle because the atrioven tricular ring (a fibrous and nonconductive connective tissue ring) separates atria from the ventricles. Slow upstroke of the action potential, which occurs due to slow voltagegated Ca2+ channels 3. Note, last to be excited are posterobasal portion of left ventricle, pulmonary conus and uppermost portion of septum. This low ventricular rate is helpful as diastolic filling is not severely impaired. Otherwise, atria and ventricles would have contracted simultaneously resulting in no ventricular filling. Conduction is Rapid in Ventricles the impulse spreads rapidly into the ventricular mus cles via HisPurkinje system (the His bundle, the bundle branches and the Purkinje fibers). Therefore, the conduction velocity is maximum in Purkinje fibers (4 m/s) in the heart. The depolarization of the ventricle starts at the left side of the interventricular septum and then crosses to the right side through the interventricular septum, and then spreads down to the apex of the heart. Then it depolarizes the muscles in the wall of the ventri cle from endocardial to the epicardial surface, proceed ing from the apex toward the atrioventricular junction. The portions to be depolarized last are the posteroba sal portion of the left ventricle, the pulmonary conus, and the upper most portion of the septum. The process of repolarization of ventricular muscle occurs almost in the reverse direction. That means, the epicardial surface repolarizes first and the septum and endocardial surface repolarize last. The rapid and synchronous excitation of the ventricles ensures almost simultaneous contraction of all ven tricular muscles, which is essential for effective ven tricular ejection of blood. Fast response action potentials are meant for immediate initiation of muscle contraction, hence seen in cardiac muscles. Slow response action potentials are seen in nodal tissues, as faster conduction of impulse through these tissues may be harmful to the heart.

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Cortex of Ovary the cortex is the outer and the major zone lined by the germinal epithelium arrhythmia games buy tenormin 50mg without prescription. The stroma of the ovary is present in between the follicles, which consists of supporting connective tissue and interstitial cells. Medulla of Ovary the inner zone of the ovary forms the medulla that contains different types of interstitial and connective tissue cells. Fallopian Tubes Two fallopian tubes (also called oviducts) arise from both sides of upper poles of uterus. First Meiotic Division the first meiotic division starts in primary oocytes during fetal life, which occurs at about 8th week of pregnancy is arrested in prophase. However, the first meiotic division is not completed in fetal life, not even till puberty; in fact, it is completed just prior to ovulation. Therefore, the life span of a primary oocyte can be up to 50 years, as ovulation can continue up to this age. The suspension of oocyte division in prophase for such a long period depends on the internal hormonal environment provided by the surrounding supporting cells. Note that the cortex contains ovarian follicle in different stages of development. The primary function of ovary is to develop ovarian follicles and release ovum at the time of ovulation, and to secrete steroid hormones that control various reproductive and metabolic functions. The oocyte degeneration however, starts from the intrauterine life so that only about 1 million primary oocytes remain at the time of birth. By the time of puberty about 200,000 and by the age of 30 only about 26,000 oocytes remain in the ovary. A major difference in male and female gametogenesis is that the process of spermatogenesis is a continuous phenomenon and the production of sperm is unlimited, whereas primary oocytes degenerate with age (Application Box 68. As new oogonia cannot be manufactured in ovary, the oocytes totally disappear at the time of menopause. The oocyte that ovulates at about 40 years of age is about 25 years older than the oocyte that ovulates at the age of 15. This one of the important factors that contribute to the anomalies in children born to older woman as the aged-eggs oocyte have degenerative changes and therefore their fertilization may result in defective embryo. Also, the process of development of each spermatocyte is completed in few days, whereas development of each oocyte that begins in intrauterine life is completed with ovulation that occurs during menstrual cycle. Thus, many sperms are produced in few days whereas single ovum is produced during each cycle, the development of which occurs at different stages of life till ovulation. The stages of development of oocytes occur in three stages: Oogonium becoming primary oocyte, primary oocyte converted to secondary oocyte, and finally secondary oocyte developing to mature ovum. Oogonia Becoming Primary Oocyte Oogonia the primordial germ cells (oogonia) migrate from the yolk sac of embryo to the genital ridge at about 6th week of gestation. The, oogonia undergo many mitotic divisions and the number of oogonia reaches to about 7 millions. Primary Oocyte Converted to Secondary Oocyte In fetus, oogonia develop into primary oocyte, which undergo first meiotic division. Thus, all eggs present at birth are primary oocytes 608 Section 7: Reproductive System. Note, first meiotic division of oocyte begins during fetal life and completes prior to ovulation, whereas second meiotic division completes at the time of fertilization. The primary oocyte that is destined for ovulation completes the first meiotic division just before the ovulation. This division results in production of two structures: one is the daughter cell, called secondary oocyte containing 23 chromosomes, and the other is the first polar body. However, the cytoplasmic division is grossly unequal in this process in which the secondary oocyte retains nearly all the cytoplasm with polar body containing very little of it. Along with development of oocyte in ovarian follicle, follicles also grow in different phases. It starts during intrauterine life and continues till ovulation that occurs during each menstrual cycle. However, only the one dominant follicle finally matures and releases ovum, whereas rest others undergo degeneration (atresia). Secondary Oocyte Forming Ovum Second Meiotic Division the second meiotic division occurs in the secondary oocyte after ovulation, and is arrested in metaphase. As a result of this meiotic division, the ovum containing 23 chromosomes and the second polar body are formed. Stage 1 (Primordial Follicular Stage) the ovarian follicle, also called Graafian follicle begins as a primordial follicle. The primordial follicle consists of a primary oocyte at the center surrounded by a layer of spindle cells (flattened pregranulosa cells) that form granulosa cells later. The oocyte enters into first meiotic division and the division is arrested in prophase. Stage 2 (Primary Follicular Stage) the primordial follicles grow into the primary follicles. During this process the flattened pregranulosa cells (spindle cells) become cuboidal granulosa cells that further proliferate to form a continuous cell layer surrounding the oocyte. A type of glassy material consisting of mucopolysaccharide is secreted from granulosa cells, which forms a thick layer between the oocyte and the granulosa cell layer, called as zona pellucida. The primordial follicle becomes primary follicle at about 28th weeks of gestation. Stage 4 (Tertiary Follicular Stage) this is the final stage of follicular development. It occurs in two sub-stages: the early tertiary stage and the Graafian follicular stage. Early Tertiary or Antral Follicular Stage In this stage, the spindle cell layer surrounding the basement membrane proliferates and differentiates into inner theca interna and outer theca externa. Theca interna cells multiply to form multiple cell layers and become steroidogenic. Theca externa cell lie in a single layer and provide mechanical support to the follicle from outside. Theca cells receive blood, lymphatic and nerve supply whereas granulosa cells remain avascular as blood vessel cannot penetrate the basement membrane. A long with the expansion of theca cell layer, a fluidfilled space is created in the midst of granulosa cells, called as antrum. Therefore, the follicle in this stage is also called early antral follicle and the stage also as early antral follicular stage. Stage 3 (Secondary Follicular Stage) the primary follicle becomes secondary follicle in this stage during which the granulosa cells divide and form several layers of cells around the oocyte. A layer of spindle cells (pre or early theca cells) is formed at the periphery of the basal lamina, which forms the theca cell layer in the next stage. Late Tertiary or Graafian Follicular Stage this is the most rapid stage of development. The size of the antrum and the amount of antral fluid are increased significantly. The mucopolysaccharide, which is present in the antral fluid, is depolymerized to increase the osmotic pressure of the fluid. It also contains plasminogen activator, mucopolysaccharide, proteins, electrolytes, glycosaminoglycans and proteoglycans. The granulosa cells in this stage are anatomically divided into three compartments: antral, cumulus and mural granulosa cells. Antral granulosa cells: Granulosa cells lining the antral cavity are called antral granulosa cells (Discus proligerous). Cumulus granulosa cells: Granulosa cells surrounding the oocyte are cumulus granulosa cells (cumulus oophoricus). Mural granulosa cells: Granulosa cells that are attached to the basement membrane are called mural granulosa cells (Membrana granulosa).

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Mechanism of Micturition the urge to pass urine is initiated with filling of the bladder arteria labyrinth cheap tenormin 100mg visa, which is sensed by stretch receptors. The stretch receptors that are present in the wall of the bladder send impulses in the afferent nerve that initiate reflex contraction. Stimulus and Reflex Arc Filling of the bladder, causing stretch of bladder wall is the stimulus. Control of Micturition the micturition reflex is controlled by centers in the brainstem. Chapter 83: Physiology of Micturition and Bladder Dysfunctions 725 of neuraxis above pons promotes activity of micturition reflex in which less filling of bladder triggers its reflex evac uation, and section above midbrain does not affect it. In children, below three years of age, cortical inhibi tion is not well developed; hence they often pass urine without their knowledge. Control on urination starts to develop at about two years of age and completes by three years. Interruption of influences from the facilitatory and inhibitory areas in the brain (spinal cord transection). In these lesions, bladder may contact, but the contrac tion is not enough to empty the viscus. Deafferentation When, fibers originating from the sacral roots of the spinal cord are experimentally destroyed, reflex contraction of bladder is abolished. However, some contractions occur (due to intrinsic response of the smooth muscles to stretch). Denervation When both the afferent and efferent fibers are cut, blad der becomes flaccid and distended at the beginning. However, gradually the muscle of the bladder becomes active and the contraction of the bladder muscle removes urine in the form of dribbles. Fullness of bladder is sensed by afferents in pelvic nerve and parasympathetic efferents also travel in pelvic nerve. Spinal Cord Transection When the spinal cord is transected, typically three phases are observed: phase of shock, phase of recovery (increased reflex activity), and phase of failure. The facilitatory area is present in pons and the inhibitory area is present in midbrain. The overflow incontinence (urine dribbles through the sphincter when the blad der is overfilled) occurs. In the phase of recovery, micturition reflex is the first reflex activity to return. However, voluntary control or control by the higher centers is abolished after transection. In the phase of failure, the infection of bladder makes the reflex activity worse. Micturition reflex, Cystometrogram, Mechanism of micturition, Abnormalities of micturition are asked as Short Questions in exam. What are the functions of internal and external bladder sphincters, What are the innervations of urinary bladder, List the functions of urinary bladder, What are the phases of a cystometrogram, How is the micturition controlled voluntarily, How is the micturition controlled involuntarily, What is deafferentation, & what are its features, What is the effect of denervation on bladder and micturition, What is the effect of spinal cord transaction on bladder and micturition. No part of this publication may be reproduced, stored or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior permission in writing of the publishers. The publisher is not associated with any product or vendor mentioned in this book. This book is designed to provide accurate, authoritative information about the subject matter in question. However, readers are advised to check the most current information available on procedures included and check information from the manufacturer of each product to be administered, to verify the recommended dose, formula, method and duration of administration, adverse effects and contraindications. It is the responsibility of the practitioner to take all appropriate safety precautions. Neither the publisher nor the author(s)/editor(s) assume any liability for any injury and/or damage to persons or property arising from or related to use of material in this book. This book is sold on the understanding that the publisher is not engaged in providing professional medical services. If such advice or services are required, the services of a competent medical professional should be sought. Every effort has been made where necessary to contact holders of copyright to obtain permission to reproduce copyright material. If any have been inadvertently overlooked, the publisher will be pleased to make the necessary arrangements at the first opportunity. In her confirmed because transformed in her, Our life shall find in its fulfilled response Above, the boundless hushed beatitudes, Below, the wonder of the embrace divine. The Mother (of Sri Aurobindo Ashram, Puducherry, India) Physiology is the key subject in medicine. Starting from the knowledge of body functions, physiology provides the concept of dysfunctions, the basis of understanding the disease processes and the insight into disease management and prevention. Due to its enormous contribution to the growth of medical knowledge, the Nobel Prize in health sector has been designated as Nobel Prize in Physiology and Medicine. Physiology as a subject in medical science has changed over the years from its nonclinical to preclinical and then to the current proclinical format with the incorporation of Applied and Clinical Physiology as the essential components in its core curriculum. Many clinical investigations related to neurological disorders, autonomic dysfunctions, cardiovascular and respiratory diseases, endocrinal, renal, reproductive and metabolic problems are carried out in the well-equipped laboratories of physiology departments. In India, Physiology as a subject in medical curriculum has changed immensely over decades. Therefore, in the present textbook, we have made all our sincere efforts without diluting the core concepts of physiology that includes regulation and integration of body functions, to amalgamate the knowledge in physiology with other subjects for its application in medicine. After the publication of our Textbook and Practical Book of Physiology, the students and teachers in Physiology across the globe have been requesting to write a comprehensive book in Physiology that can offer a holistic concept of functions, integration, dysfunctions of body systems, and physiological basis of management and prevention of diseases. With all their wishes and blessings, finally this book has been made available to them. We hope this book will fulfill the aspiration of the readers in acquiring and applying the knowledge of physiology in clinics. Nevertheless, this is a project in evolution, and needs inputs, support and encouragement from our readers for its endless progression. Gopal Krushna Pal Pravati Pal Nivedita Nanda Acknowledgments Let us work as we pray. We sincerely acknowledge the contribution of Shri Jitendar P Vij, Group Chairman, Jaypee Brothers Medical Publishers Pvt Ltd, New Delhi for personally coming to Puducherry, and motivating and inspiring us to take up this special responsibility of writing such a wonderful book. For preparing the manuscript of the present book, we are especially thankful to Ms Chetna Malhotra Vohra (Associate Director - Content Strategy) and Ms Angima Shree (Senior Development Editor) for their constant support and timely help. We also thank the other editors and designers of the Jaypee group who helped in the preparation of this book. We acknowledge Mr Narendra Singh Shekhawat (Delhi, India), Mr Venugopal (Bengaluru, Karnataka, India), and Mr Muralidharan (Puducherry, India) of the Jaypee group for their support. We are also thankful to Jaypee Brothers Medical Publishers for providing us many of the pictures and materials of their medical publications. We are thankful to all our colleagues and students across the globe for reading our book and providing us their inputs for its further improvement. Auroprajna and Auroprakash, the divine children gifted to us, have been the constant support to us in all our endeavors. We shall fail in our duty if we do not appreciate the contribution of our sister Sabita Nanda, who has been constantly taking care of all our family requirements. We always keep in high esteem our parents Dr (Late) Artatran Nanda, Smt Anupama Nanda, Sri Mrutyunjay Pal and Srimati Malatimani Pal for showering on us their love and blessings and providing us everything to come to the greater heights in our life. We take this opportunity to express our heartfelt obeisance to Ms Kumud Ben of Sri Aurobindo Ashram, who is no more physically on this earth but lives in our hearts forever. Special Features of the Book/How to use it Best All sincere prayers are granted, every call is answered. The Mother (of Sri Aurobindo Ashram, Puducherry, India) this Comprehensive Textbook of Medical Physiology has the following special features. By reading the learning objectives, a student will know the gross content of the topic, and how much he should acquire from it after reading the topic. Scientists Contributed: Invariably, important topics start with the contributions of great scientists in the concerned field, especially those who have received the Nobel Prize and/or are popular for their contributions in that field. Often, examiners ask to name the scientists who have invented/discovered the concepts or profoundly contributed to the development of the subject. This will not only give the information of the history of medicine, but will also inspire students and teachers to take up research in physiology and medicine. Application Box: the concepts of Physiology have lot of applications in daily life and medical practice.

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These are the series of reflexes that are integrated in the spinal cord and mediated via autonomic and somatic nerves hypertension migraine order discount tenormin online. Male genital tract receives both sympathetic and parasympathetic innervation, and in addition, penis receives the somatic innervation. Though the sexual act per se is mainly a neural process, its overall integration is a behavioral phenomenon that includes hormonal, biochemical and psycholo gical interactions. Mechanism Erection occurs due to dilatation of the penile arterioles filling the erectile tissues of the penis by blood. The erec tile tissues of penis are three in numbers: two corpora cavernosa and a corpus spongiosum. In normal state, penis is flaccid due to paucity of blood in the spaces of these erectile tissues. Upon arousal, mainly the spaces in cavernous erectile tissue fill with blood and penis becomes turgid. Relaxation of the smooth muscles of corpora allows increased flow of blood into corporal interstices (caver nous spaces) that increases the volume and rigidity of the penis. As veins are compressed by the erectile tissues filled with blood, engorgement of penis inhibits venous return and keeps the interstices filled with blood, which maintains erection. Blood supply to penis is from internal pudendal artery that enters penis from its dorsal surface as dorsal artery and penetrate deep into the organ as deep artery. Parasympathetic Control Penile erection is mainly achieved by parasympathetic activity that relaxes smooth muscles of corpora, causes vasodilation and increases blood flow to the corporal interstices. It is the inability to keep the penis adequately erected to be pen etrated into the female genital tract. But it can regularly happen due to physical problems and neural deficits that causes deficit in sexual reflexes. Causes and Treatment Both psychological and biological factors can play a role in premature ejaculation. Although many men feel embar rassed to talk about it, premature ejaculation is a common and treatable condition. Regular counseling, learning the proper sexual techniques and few medications can delay ejaculation. As penile erection is a parasympathetic and ejacula tion is a sympathetic mechanism, the male partner has to learn to delay the sympathetic activation during sex to avoid early ejaculation. Ejaculation Ejaculation is the emission of semen from the male genital tract and its propulsion out of the urethra at the time of orgasm. Emission Normally, sperms are stored in epididymis and proximal part of vas deferens. It is a sympathetic response that occurs due to contraction of smooth muscle of vas deferens and seminal vesicles. The female responses are characterized by marked increase in blood flow and muscular activities in many parts of the body. Increased sexual excitement is accompanied by engorgement of the breasts and erection of the nipples, increased diameter and length of clitoris due to increased blood flow into these structures. Therefore, clitorial and nipple stimulations during sex ual act add to sexual excitement. Sexual desire in women is possibly dependent on androgens, because sex drive is maintained long after the menopause, when estrogen level in plasma is very low. Therefore, it is believed that androgens secreted by the adrenal glands maintain sexual appetite in females. This is a spinal reflex integrated at lower lumbar and upper sacral segments of spinal cord (L5, S13). When this sphincter fails to constrict, the sperms instead of passing down the urethra enter the urinary bladder. The quantity of ejaculate decreases and sperms appear in urine (more than 15 sperms per high power field). Usually it occurs in diabetic neuropathy, multiple sclerosis and use of sympatholytic drugs. Chapter 71: Physiology of Copulation 633 Vaginal Changes Vaginal secretion increases during sexual excitation and intercourse. The stimuli for vaginal secretion are tactile stimulation of clitoris, labia minora, breast and sexual excitement. The sexual gratification in females culminates in orgasm that manifests as rhythmic vaginal contractions mediated by autonomic influences (Application Box 71. As female is the passive partner in the sexual act, orgasm in females comes usually later. Therefore, the male partner should learn to stimulate the female partner appropriately and adequately even before the initiation of intercourse so that orgasms in both arrive together. In males, orgasm occurs with ejaculation, following which the penis becomes flaccid. Unless female orgasm is attained along with the male orgasm, the female does not derive actual pleasure from the act, and repeated failure to attain orgasm in females is harmful both physically and mentally. Therefore, gradually the male should know the time of orgasm of his partner and should learn to maintain penile erection till then. Orgasm (climax) in female is associated with a pleasurable feeling accompanied by sudden increase in skeletal muscle activity, increased heart rate and blood pressure, and rhythmic contraction of the vaginal wall. Though, vaginal contraction during orgasm facilitates sperm trans port, it is not essential for fertilization since conception can occur in the absence of orgasm. Increased skeletal muscle activity All these changes are due to increased epinephrine secretion into the circulation. There may be associated stimulation of the anterior pituitary, adrenal cortex and the thyroid gland. Uterine muscular movements and ciliary activity may aid in migration of sperms within the uterus. Some spermatozoa can survive in a viable state within the slightly alkaline medium of the cervical mucus for up to 48 hours. Therefore, to one must learn to delay the sympathetic activation to avoid early ejaculation. The orgasms of male and female partner should occur simultaneously in an effective sex. Male sexual responses, Female sexual responses, and Orgasm, may be asked as Short Questions in exam. Understand the physiology at different steps of pregnancy starting from fertilization to fetal maturation. Pregnancy is the most precious event in the life of a married woman as it proves her fertile capability, and brings completeness to her womanhood. The introduction of sperm into the female genital tract should ideally occur in the period of two days before and one day after ovulation. This is because the sperms following their ejaculation into the vagina remain capable of fertilizing an egg usually for 24 to 48 hours (though they may survive for 3 to 5 days in the female genital tract) and the fertilizable life of the ovulated egg is about 24 hours. Thus, if ovulation occurs on 14th day of the cycle, for conception to occur the coitus should take place on 12th, 13th, 14th, and 15th days (the fertile period) of the menstrual cycle). The fimbriae located at the end of the fallopian tube actively pick up the oocyte. Immediately after ovulation, smooth muscle of the fimbriae contract, which make the fimbrial end of the tube migrate close to the oocyte. These ciliary motions sweep the egg into the fallopian tube as the egg emerges from follicle to the ovarian surface. Inside the fallopian tube, egg movement is driven by fallopian-tube cilia, which is a normally a slow process. Hence, for fertilization to occur, it must naturally happen in the distal portion of fallopian tube (within a day of ovulation) because of the short viability of the unfertilized egg. Transport of Sperm During the act of intercourse, some sperms are propelled from the vagina to the cervix, and many enter cervical canal after the sexual act.

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Plasmin also activates the synthesis of collagenase that causes destruction of connective tissue matrix of the follicular wall and adjacent ovarian capsule blood pressure zoladex best order tenormin. Increased intrafollicular pressure and degeneration of the follicular wall facilitate the rupture of the follicle, which results in expulsion of oocyte from the follicle and the ovary. Four days before and after ovulation (10th to 19th day of the cycle) is called unsafe period as unprotected sex leads to conception. Rest of the period is considered relatively safe, as chance of conception is minimal during these days. Indicators of Ovulation It is important to know the day of ovulation for its physiological and clinical significance. It is recorded orally, early in the morning before getting up of the bed, and before taking any drink or washing the mouth. The increase in body temperature is due to the influence of progesterone that starts increasing with the beginning of secretory phase. Fleeting lower abdominal pain (mittelschmerz): With ovulation, bleeding occurs into the antrum of the follicle. Small amount of blood also escapes into the abdominal cavity, which causes peritoneal irritation and produces fleeting (short-lived) lower abdominal pain. Vaginal discharge (spotting): There may be transitory increase in vaginal discharge during ovulation. If all the three features are present, occurrence of ovulation is almost confirmed. Spinnbarkeit: In the proliferative phase, estrogen makes the cervical mucous thin and alkaline. With the beginning of secretory phase, progesterone secreted from corpus luteum makes the cervical mucous thick and tenacious. Thus, uterine mucous is thinnest at the time of ovulation and its elasticity is maximal. Therefore, a drop of cervical mucous collected at the time of ovulation can be stretched to as long as 10 cm or more like a thread. Fern test: Under the effect of estrogen, the cervical mucous before ovulation forms an arborizing fern like pattern, when the mucous is spread on a slide. Following ovulation, due to progesterone effect, the mucous become thick and fern pattern is not observed in smear of the mucous. Laparoscopic observation: Demonstrating ovum in the abdominal cavity by laparoscopy confirms ovulation. Physiological Importance Determination of day of ovulation helps in family planning. Therefore, those who are desirous of a child, should have regular sexual act in the periovulatory period (day of ovulation, and two days before and after the ovulation). Those who want to avoid pregnancy, should not have unprotected sexual act during the unsafe period (day of ovulation, four days before and after ovulation) of the cycle. Thus, it helps in planning both conception and contraception (for details, see "Female Contraceptives"). Amenorrhea is broadly classified into two categories: primary and secondary; each category subdivided into physiological and pathological. Primary Amenorrhea When menstruation has never occurred, the condition is called primary amenorrhea. Physiological Primary Amenorrhea Amenorrhea occurs in many physiological conditions. Constitutional amenorrhea: Though menstrual cycle starts normally by the age of 16 years, sometimes it may not occur even at the age of 18 years or more, without there being any abnormality. Lactation: the prolactin concentration is high in the plasma of a lactating mother. Change in environment: Sudden change of place, especially exposure to extremes of climates is known to produce amenorrhea during the acclimatization period. Pathological Secondary Amenorrhea Pathological secondary amenorrhea occurs due to a defect in hypothalamus, pituitary, ovary and uterus or due to a systemic disease or chronic use of some drugs. Recently, it has been observed that this occurs due to increased opioid activity and treatment with opioid blockers like naltrexone cures hypothalamic amenorrhea. Pituitary disorders: Tumors and other diseases of pituitary (hypopituitarism) resulting in decreased secretion of gonadotropins leads to amenorrhea. Ovarian diseases: Diseases that decrease the produc tion of estrogen and progesterone, frequently lead to amenorrhea. Uterine pathology: Congenital absence of uterus, underdeveloped uterus and severe infective or noninfective endometritis produce amenorrhea. Systemic illness: Amenorrhea occurs in chronic illnesses like chronic hypothyroidism, chronic renal failure and cirrhosis of liver. Drugs: Phenothiazine derivatives, reserpine, ganglion blocking agents and estrogen-progesterone preparations (pill contraceptives) are common drugs that prevent menstrual cycles. Pathological Primary Amenorrhea When menstrual cycle does not start till the age of 18 years due to some prevailing disease, the condition is called pathological primary amenorrhea. Congenital malformations of reproductive tract like absence of uterus can also cause primary amenorrhea. Secondary Amenorrhea When menstrual cycle stops in a woman who had normal cycles before, the condition is called secondary amenorrhea. Physiological Secondary Amenorrhea Physiological causes of secondary amenorrhea are more common than pathological causes. Peri-pubertal amenorrhea: In first one to two years of onset of menarche, menstrual cycles are often anovulatory and therefore irregular. This very common till the full pubertal and reproductive developments occur and is regarded as normal. It is so common amongst all forms of amenorrhea that before investigating for the causes of amenorrhea, first, pregnancy should be ruled out. Chapter 69: Menstrual Cycle and Ovulation 621 Anovulation Absence of ovulation during a menstrual cycle is called anovulatory cycle. Few cycles may also be anovulatory in lactating woman, and about six months before menopause. Anovulation also occurs in severe strenuous exercise or severer job related stress. Except these physiological situations, anovulation is abnormal and occurs mainly due to hormonal deficiencies. It is generally caused by conditions that affect uterus and its vascular apparatus rather than any ovarian dysfunction. Metrorrhagia Bleeding occurring between the periods (acyclical and irregular) is called metrorrhagia. It usually indicates a surface lesion in the genital tract, which may be benign or malignant. Polymenorrhea When menstrual cycle occurs frequently (less than 21 days), it is called polymenorrhea. If amenorrhea is due to pituitary tumor, their surgical removal should be considered. Clomiphene, that binds with estrogen receptors and blocks estrogen action, induces ovulation. Features: the usual features are edema, painful or swollen breasts, depression, loss of concentration, irritability, headache, behavioral changes, and emotional disturbances. Also, the plasma concentrations of hormones usually found to be normal in these patients. Hypomenorrhea and Oligomenorrhea Decreased menstrual bleeding in duration or amount or both is called hypomenorrhea. It may be constitutional, or due to uterine pathology or due to hormonal disorders. Decreased frequency (cycle more than 35 days) of menstrual cycle is called oligomenorrhea. Usually, oligomenorrhea occurs in ovarian diseases in which menstruation is irregular and infrequent. Secondary dysmenorrhea in which a uterine or pelvic pathology is associated with it.

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Postero-ventral Dorsal-lateral Pulvinar Dentatothalamic tract heart attack or heartburn discount tenormin 100mg, and pallidothalamic tract Thalamocortical tract (to motor area 4 and 6) Proprioceptive input to control of voluntary Relay of all somatosensory inputs including face. Vision Audition Memory and emotion Integration of somatic and visceral sensations, and arousal. Major Afferents Major Efferents Functions 1031 Spinothalamic fibers, trigeminothalamic To sensory cortex fiber, & medial lemniscus. Nonspecific Nuclei Anterior group Midline group Intralaminar Dorso-medial synthesis to the motor cortex (via thalamocortical fibers), which projects back to the basal ganglia. Thalamus also links cerebellum and motor cortex via dentatorubro-thalamo-cortical tract. Through this connection, thalamus influences planning and programming of movements. Role in Sleep: A circuit linking the thalamus and cortex (thalamocortical loop) is important in generating the pattern of brain activity in sleep-wake cycle. Inhibitory thalamic reticular neurons are proposed to be the part of this neuronal network that causes induction of sleep. Sensory Motor Coordination: Thalamus receives all sensory inputs from the body and closely interacts with basal ganglia, cerebellum and motor cortex. Therefore, thalamus is one of the major structures in the brain for coordination between sensory and motor functions, especially in the sensory feedback for correction and improvement in motor output. Language and Speech: Dorsal lateral nucleus of thalamus is reciprocally connected with parietal lobe of the brain, and therefore is concerned with language and speech and complex integrated functions. This results in severe impairment of the discriminative touch and pressure sensations of contralateral side, whereas diffuse touch, temperature, and pain sensations are often less impaired. Other Deficits When the thalamus is damaged, not only thalamic functions are lost, but also many cortical functions are affected, as cortex is intimately connected with thalamus. Electrical lesion of intralaminar nuclei relieves chronic suffering type of pain, though the acute perception of pain remains intact. Subthalamus contains sensory fasciculi, rostral extensions of midbrain nuclei, fiber bundle from cerebellum and globus pallidus, and subthalamic nuclei. The subthalamic nucleus (body of Luys) has reciprocal connection with the globus pallidus. Lesion of subthalamic nucleus results in hemiballismus (for detail, see Basal Ganglia). Though thalamus is major relay center of all sensations, it interacts and integrates with many brain areas and functions. The specific nuclei (ventral, lateral, anterior, posterior group) covey sensations to sensory cortex. The nonspecific nuclei (intraluminal and midline group) interact with reticular formation and cortex for arousal mechanisms. Thalamic nuclei, Connections and functions of thalamus, Functions of thalamus, thalamic syndrome, may come as Short Questions. Name the thalamic nuclei, Connections and functions of each nuclear group of thalamus, What are the specific and nonspecific nuclei of thalamus and what their functions, What is thalamic syndrome. Third order neurons of ascending sensory pathways project to the somatosensory cortex. There are other somatosensory cortical areas that are called secon dary somatosensory cortical areas. There are minimum four distinct areas in the cortex that receive somatosensory inputs. Supplementary sensory area: this is part of the posterior parietal association area located on the medial wall of the parietal lobe. Precentral gyrus (area 4): Though this is the primary motor cortex, it also receives somatosensory signals. Connections of Somatosensory Areas Somatosensory areas are interconnected to each other. That means whether they respond to cutaneous (from the skin) or deep (from muscles and joints) stimuli. Area 5 receives input only from the lateral posterior nucleus of the thalamus, which does not receive direct somatosensory inputs. In this sensory map in brain, face is represented in the lateral part, hand and upper extremity are represented in the dorsolateral part of the postcentral gyrus, and lower extremity on the medial surface of the hemisphere. The greatest area of the map is devoted for face, especially lips (area devoted for speech), and hand, especially the digits (cutaneous sensations from areas involved in skilled activities). Cortical columns that are located adjacently process different sensory modalities. For example, the column in the area 3b responds to cutaneous stimulation (that come from rapidly adapting mechanoreceptors), whereas the column in the area 3a responds to deep stimulation (mainly from slowly adapting mechanoreceptors). It also processes higher sensory orders like perception of the direction of an applied stimulus. Supplementary sensory area Effects of Lesions Cortical lesions do not completely abolish somatic sensation. Cortical sensations (tactile localization, tactile Chapter 123: Sensory Cortex 1035. With selective lesions of area 3, there is failure to learn the discriminative task even after repeated trials. Lesion of area 1 causes significant impairment of hardsoft, or smooth-rough discrimination, but no deficit in other aspects of sensory learning. Damage to postcentral gyrus also causes impairment of kinesthesia (inability to appreciate passive position and movements of different body parts). Damage to area 5 specifically affects stereognosis, with other tactile sensation remaining intact. Association Cortex Association sensory cortex is present in the parietal lobe (parietal association cortex). The major function of the parietal association cortex is to coordinate the relationship of the body to extrapersonal space. In the non-dominant hemisphere, the association cortex is involved in spatial relations, whereas in the dominant hemisphere it is concerned with language. A lesion of parietal association cortex of the nondominant hemisphere produces impairments in the ability to relate to extrapersonal space. For example, if the subject is asked to copy a geometry, the figures are distorted. The person develops constructional apraxia (defect in constructing a picture) and hemineglect syndrome (he denies existence of the opposite side of the body). The topographic organization is such that head is represented at the inferior end of the postcentral gyrus and the feet at the bottom of the sylvian fissure. The hand and face are more represented in sensory cortex, as these parts are most used by human beings. Correlate the knowledge of sensory physiology in understanding the abnormalities of sensory system. Understand the sensory deficits produced by lesion at different levels of sensory system. It also helps us learn the physiological basis of diag nosis and management of the sensory abnormalities. It is not only important to detect the nature of the deficit, but also to localize the site (the level of the sensory neuraxis) of sensory deficit. The detection and localization of lesions of the sen sory system depend on the distribution and type of sensory loss. The disease may affect the nerve, the nerve roots, the spinal cord, the brainstem, the thalamus, and the cortex. He also studied glands of internal secretion, showing indispensability of the adrenals. He is remembered for his classic description of pathways of conduction in tracts in spinal cord. Lesion of a cutaneous nerve results in sensory loss in the corresponding areas of distribution of that parti cular nerve. However, deficit is always less than the anatomic dis tribution because of overlap from the adjacent nerve. Perception of deep pressure and passive movements is usually not affected, as these modalities are medi ated by nerve fibers from subcutaneous structures and joints. If the nerve is affected by compression, large fibers car rying touch and pressure are affected whereas small fibers carrying pain and temperature remain intact.