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A plant may thrive in loam and yet wilt in a clayey soil with twice the moisture content cheap cialis super active 20mg with mastercard erectile dysfunction pills generic. Many of these insects are adapted to utilize the surface tension of water for locomotion cialis super active 20 mg overnight delivery impotence natural supplements. The surface tension of water makes it possible for some insects to stand on water and remain dry. As is shown in Exercise 7-11, a 70 kg person would have to stand on a platform about 10 km in perimeter to be supported solely by surface tension. The threads are aligned in a regular pattern with spaces between threads so that the threads can slide past one another, as shown in Fig. The calcium ions in turn produce conformational changes that result in the sliding of the threads through each other, shortening the myosin-actin structure. Clearly, a force must act along the myosin-actin threads to produce such a contracting motion. It has been suggested by Gamow and Ycas [7-5] that this force may be due to surface tension, which is present not only in liquids but also in jellylike materials such as tissue cells. Here the movement is due to the attraction between the surfaces of the two types of thread. Let us now estimate the force per square centimeter of muscle tissue that could be generated by the surface tension proposed in this model. If the average diameter of the threads is D, the number of threads N per square centimeter of muscle is approximately 1 N (7. There- fore, the maximum contracting force that can be produced by surface tension per square centimeter of muscle area is 6 2 Fm T 4 10 dyn/cm A surface tension of 1. Because this is well below surface tensions commonly encountered, we can conclude that surface tension could be the source of muscle contraction. The actual processes in muscle contraction are much more complex and cannot be reduced to a simple surface tension model (see [7-7 and 7-9]). As the word implies, the hydrophilic end is strongly attracted to water while the hydrophobic has very little attraction to water but is attracted and is readily soluble in oily liquids. Many dierent types of surfactant molecules are found in nature or as products of laboratory synthesis. When surfactant molecules are placed in water, they align on the surface with the hydrophobic end pushed out of the water as shown in Fig. Such an alignment disrupts the surface structure of water, reducing the surface ten- sion. A small concentration of surfactant molecules can typically reduce sur- face tension of water from 73 dyn/cm to 30 dyn/cm. In oily liquids, surfactants are aligned with the hydrophilic end squeezed out of the liquid. The most familiar use of surfactants is as soaps and detergents to wash away oily substances. Here the hydrophobic end of the surfactants dissolves into the oil surface while the hydrophilic end remains exposed to the surround- ing water as shown in Fig. As a result, the oil breaks up into small droplets surrounded by the hydrophilic end of the surfactants. The small oil droplets are solubilized (that is suspended or dissolved) in the water and can now be washed away. In certain types of experiments, for example, proteins that are hydrophobic such as membrane proteins and lipoproteins must be dissolved in water. Here surfactants are used to solubilize the proteins in a process similar to that illustrated in Fig. The hydrophobic ends of the surfactant molecules dissolve into the surface of the protein. The aligned hydrophilic ends surround the protein, solubilizing it in the ambient water. They secrete a substance from their abdomen that reduces the surface tension behind them. Here the eect is similar to cutting a taut rubber membrane which then draws apart, each section moving away from the cut. This eect known as Marangoni propulsion can be demonstrated simply by coating one end of a toothpick with soap, and placing it in water. The soap acting as the surfactant reduces the surface tension behind the coated end resulting in the acceleration of the toothpick away from the dissolved soap. Experiments have shown that the surfactant excreted by insects reduces the surface tension of water from 73 dyn/cm to about 50 dyn/cm. Measurements show that during Marangoni propulsion, Microvelia can attain peak speeds of 17 cm/sec. Assume that the average density of the human body is about the same as water ( 1 g/cm3) and that the area A of the limbs w acting on the water is about 600 cm2. If the situation is reversed, the immersed animal tends to rise to the surface, and it must expend energy to keep itself below the surface. Calculate volume of the swim bladder as a percent of the total vol- ume of the sh in order to reduce the average density of the sh from 1. The density of an animal is conveniently obtained by weighing it rst in air and then immersed in a uid. If the density of the uid is 1, the average density 2 of the animal is W1 2 1 W1 W2 Derive this relationship. If a section of coarse-grained soil is adjacent to a ner grained soil of the same material, water will seep from the coarse-grained to the ner grained soil. Calculate the perimeter of a platform required to support a 70 kg person solely by surface tension. Assume that the linear dimension of the insect is 3 101 cm and its mass is 3 102 g. Further, assume that the surface tension dierence between the clean water and surfactant altered water provides the force to accel- erate the insect. Poiseuille (17991869), was a French physician whose study of moving uids was motivated by his interest in the ow of blood through the body. In this chapter, we will review briey the principles governing the ow of uids and then examine the ow of blood in the circulatory system. Bernoullis equation states that at any point in the channel of a owing uid the following relationship holds: 1 2 P + gh + v Constant (8. The rst term in the equation is the potential energy per unit volume of the uid due to the pressure in the uid. Consider a uid owing through a pipe consisting of two segments with cross- sectional areas A1 and A2, respectively (see Fig. The volume of uid owing per second past any point in the pipe is given by the product of the uid velocity and the area of the pipe, A v. If the uid is incompressible, in a unit time as much uid must ow out of the pipe as ows into it.

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Hypothyroidism Definition: Primary hypothyroidism: refers to a thyroid hormone deficiency as a result of thyroid gland disease cheap 20 mg cialis super active overnight delivery erectile dysfunction cialis. Etiology: Without thyroid enlargement Hypothyroidism frequently develops following treatment of Graves disease with 131I therapy or thyriodectomy buy cialis super active us zolpidem impotence. With thyroid enlargement Chronic thyroiditis /Hashimotos thyroiditis is one of the most common causes of spontaneous hypothyroidism. This is known and myxedema Yellowish dry skin Nonpitting edema Hypothermia Bradycardia A delay in return phase of Achilles and other deep tendon reflexes is a specific finding. Cretinism: is sever hypothyroidism beginning in infancy infants may have Hypotonia, umbilical hernia, Delayed mental and physical development, and mental retardation may result if hypothyroidism goes untreated in the first few years of life. Rapid initiation Younger patients and patients with less sever hypothyroidism, may be started on slightly higher dose ( 50 g of L-thyroxin ) and advanced to a full replacement dose more quickly (e. Myxedema Coma Definition: Myxedema coma results from severe chronic hypothyroidism, which is left untreated, and is life threatening clinical condition. Ancillary treatment: Temporary use of glucocorticosteriods Respiratory support Hypothermia and heat loss should be avoided D. Thyroid enlargement Goiter A goiter is a simple enlargement of the thyroid gland. Signs and symptoms: Symptoms: Thyromegaly, occasionally with rapid enlargement and tenderness secondary to haemorrhage into a cyst. Occasionally it may be difficult to distinguish from the typically lobulated, irregular Hashimotos gland. Diagnosis: Thyroid function tests: Performed to rule out hypo or hyperthyroidism Malignant transformation is rare, but should be considered if the gland is enlarging rapidly or hoarseness develops. Treatment: The main indications for treatment are compression of the trachea or esophagus and venous- outflow obstruction. For toxic multinodular goiter, options are Antithyroid agent Surgery Radioiodine, and more recently Percutaneous injection of ethanol in to the toxic nodule Solitary Nodules They are usually benign. Diagnosis: History and Radio iodine thyroid scan should be done on every patient with a solitary nodule. Hot nodules that take up the radioisotope are generally benign but fine-needle aspiration of a solitary nodule is prudent. Treatment: Is indicated if signs of compression of trachea, esophagus, significant growth, and recurrence of a cystic nodule after aspiration. Subacute Thyroiditis/granulomatous thyroiditis Etiology: the cause is generally considered as viral. Clinical features: Early symptoms: prodromal phase of malaise, upper respiratory symptoms, and fever that lasts 1-2 weeks. The gland usually return to normal size, if enlargement persists, chronic thyroiditis should be suspected. Diagnosis; Acutely swollen, tender an painful thyroid gland associated with symptoms of hyperthyroidism Radioactive uptake: low radioactive iodine uptake in the face of high serum T3 and T4 level. Chronic Thyroiditis (Hashimoto thyroiditis) Etiology: it is an autoimmune disorder that mainly affects women. Clinical features Thyroid gland enlargement: is the main clinical manifestation, is the result of autoimmune damage that leads to lymphocytic infiltration, fibrosis and weakens ability of the thyroid to produce hormone. Types/ Classification: Papillary carcinoma : which accounts for 60 % of all thyroid cancer o Affects younger age group 50 % of patients are younger than 40 years o Papillary Ca metastasize through the lymphatic system Follicular carcinoma; comprises 25 % of all thyroid cancer o Histologicaly resembles normal thyroid tissue, o Follicular Ca metastasizes hematogenously Medullary carcinoma: which accounts for 5 % of all thyroid cancers. Diseases of the adrenal gland Learning objectives: at the end of this lesson the student will be able to: 1. Identify the clinical manifestation of diseases of the adrenal gland, with special emphasis on Cushings syndrome and Addisons diseases. Disease of the adrenal cortex a) Resulting from excess production of hormones Cushings syndrome : excess cortisol production Primary hyperaldosteronism : excess production of aldosteron b) Inadequate production; Addisons diseases : inadequate production of cortisol and aldosteron 2. Disease of the adrenal medulla Pheochromocytoma: excess production of catecholamine Cushings Syndrome ( Hypercortisolism) Cushings syndrome: is caused by excessive concentration of cortisol or other glucocorticoid hormones in the circulation Etiology: a) Bilateral adrenal hyperplasia (Cushings diseases) is the commonest cause of Cushings syndrome. Pituitary tumors large enough to be seen by skull x-ray, are present in more than 10 % of these patients, and smaller basophilic adenomas are found in more than 50 % of patients. It is an expected complication in patients receiving long term glucocorticiod treatment for asthma, arthritis, and other conditions. Clinical features Central obesity is caused by the effect of excess cortisol on fat distribution. The moon face, buffalo hump ( cervical fat pad ) and supraclavicular fat pads contribute to the Cushingiod appearance Hypertension : result from the vascular effects of cortisol and sodium retention Decreased glucose tolerance: is common, 20 % of patients have overt diabetes. This is a result of hepatic gluconeogenesis, and decreased peripheral glucose utilization. Because this test is sensitive, the diagnosis of Cushings syndrome need not be considered further in these cases. Serum cortisol level: in normal in individuals is highest in early morning and decreases throughout the day, reaching a low point at about midnight. Although the morning level may be increased in patients with Cushings syndrome, a loss of the normal diurnal variation and an increase in the evening level are more consistent findings. The 24 hrs urinary free cortisol excretion rate: is increased in most patients with Cushings syndrome 6. Other tests: lukocytosis, with relatively low percentage of lymphocytes and eosinophils 7. Skull x-ray: enlargement of sella turcica in 10 % of patients with Cushings syndrome who have macroadenoma. Adrenal adenoma : complete surgical resection of the adenoma cures the disease, but patients may need cortisol replacement post operatively for several months 2. Pituitary radiation : is effective in children but it cures fewer than 1/3 of adult patients b. Disadvantages Patients will develop Addisons disease and need lifelong Cortisol replacement Nelsons syndrome: in which pituitary adenomas undergo rapid growth, perhaps because it is no longer inhibited by above normal level of cortisol. Hyperaldosteronism Aldosteronism: is a syndrome associated with hypersecretion of the mineralocorticoid, aldosterone. Primary aldosteronism: the cause of excess aldosterone production resides with in the adrenal gland Aldosterone producing adrenal adenoma (Conns syndrome): in most cases, unilateral small adenoma which can occur on either side Adrenal carcinoma: rare cause of aldosteronism Bilateral cortical nodular hyperplasia /idiopathic hyperaldosteronism 2. Secondary aldosteronism: the stimulus for excess aldosterone production is outside the adrenal gland. Signs and symptoms: Moat patients have diastolic hypertension resulting from sodium retention. Patients may complain headache and symptoms of other organ damage Hypokalemia and associated symptoms: muscle weakness and fatigue. While raised aldosteron level with reduced plasma renin activity suggests primary aldosteronism. Surgery: removal of solitary adenoma results cure of hypertension in about 60 % of cases and improvement in another 25 %. Adrenalectomy is done after 4 week treatment with spironolactone (in case of adenoma, hyperplasia) In contrast only 20%-50 % of patients with bilateral hyperplasia are improved with surgery, even if bilateral adrenalectomy is performed. Medical Therapy: Spironolactone inhibits the effects of aldosteron on renal tubule. In idiopathic form: Spironolactone (50-100 mg/d), possibly combined with potassium- sparing diuretics correct the hypokalemia and with anti-hypertensive medication, high blood pressure can be controlled.

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It is most commonly due to thyroid gland dysfunction (hyperthyroidism) purchase cialis super active with visa impotent rage violet, but can Clinical presentation occurwhenexogenousT4and/orT3istakeninexcess cialis super active 20 mg with visa impotence remedies. If untreated illness, surgery or radioiodine therapy may serve as coma and death may ensue. System/organ Features Eyes Exophthalmos/proptosis Investigation (may be unilateral). May be used as rst line therapy (especially for toxic extent of eye disease in Graves ophthalmopathy. Potential complications include haemorrhage, and respond to antihistamines or changing agent) vocal cord paresis, hypoparathyroidism and andthemoreseriousagranulocytosisand/orthrom- hypothyroidism. Hypothyroidism is the clinical condition resulting from low levels of circulating thyroid hormones. The term myxoedema refers to the deposition of muco- Atrial brillation polysaccharide beneath the skin, producing a non-. Atrial brillation responds poorly to digoxin and pitting swelling of the subcutaneous tissues. Anticoagulation is also required as the risk of em- $10 : 1), reecting the high proportion of cases due to bolisation is relatively high. This is a rare but potentially life-threatening disorder, Aetiology which requires urgent treatment targeted at various steps in the thyroid hormone synthesis/action ThecausesofhypothyroidismareshowninTable16. Block peripheral manifestations of excess thyroid be asymptomatic or manifest mild hypothyroid hormones: propranolol (initially 0. Pregnancy untreated maternal hypothyroidism is Verapamil can be used in those with a history of associatedwithhigherratesofmiscarriage,stillbirth asthma. Hashimotos thyroiditis typically associated with agoitre:atrophicthyroiditiswhentheglandatrophieswithoutproducing a goitre) Previous treatment for thyrotoxicosis (e. Anaemia (microcytic if menorrhagia, macrocytic if gestive of a central (hypothalamic/pituitary) dis- co-existent pernicious anaemia, or normocytic). Standard treatment is with levo-thyroxine (L-T4), s disease developing/relapsing in the post-partum typically beginning with a dose of 50mcg/day. Myxoedema coma: treatment includes ventilatory tures and the pituitary gland sits within a bony seat, and circulatory support, correction of hypothermia the sella turcica (Fig. The optic chiasm lies just and hypoglycaemia, glucocorticoid replacement above the pituitary fossa, and on either side are the until normal adrenal reserve is demonstrated, treat- cavernous sinuses (venous lakes) through which the ment of precipitating event and thyroid hormone intracavernous carotid artery passes. The third, replacement (L-T4 or L-T3 dose and regimen fourth, upper division of the fth and sixth cranial should be decided in conjunction with an nerves lie within the lateral and inferior aspects of the endocrinologist). Thyroiditis Thesphenoidsinus,whichisbelowthepituitaryfossa, Acute thyroiditis is the route through which the pituitary gland is ap- proached during transsphenoidal surgery (Fig. Although relatively uncommon, acute thyroiditis Thehypothalamusandpituitaryworkinconcertto may follow an upper respiratory tract or other regulate a number of different endocrine systems infection. Hypothalamic releasing fac- swellingand tenderness of theglandand sometimes tors (e. Occasionally prednisolone 30mg/day is necessary, the inhibitory hormones somatostatin and dopamine but this can usually be tailed off rapidly. The term hypopituitarism denotes an insufciency of Knowledge of the anatomy and physiology of the one or more of the anterior or posterior pituitary hypothalamus and pituitary helps to understand the hormones. With pituitary tumours, the usual se- different presentations of patients with sellar and quence in which pituitary hormone function is lost parasellar lesions. In contrast, vasopressin and oxytocin are transported along axonal projections fromthehypothalamustotheposteriorpituitaryandstoredinvesiclespriortorelease. Negativefeedbackatthelevel of the pituitary and hypothalamus is mediated via hormones secreted by target organs (shown in italics). In the majority of cases patients present with features of one or more of hormone Destruction/compression of the normal pituitary tis- hypersecretion, hormonehyposecretion or local mass sue or reduction in the blood supply (including effects, as outlined above. Aside from a small number of genetic cases, the factors underlying pitutary adenoma for- Prolactinomas are the most commonly encountered mation remain poorly understood. Clinical presentation Hyperprolactinaemia per se is associated with This is variable and depends on not only the aetiology reduced libido in both sexes and galactorrhoea in but also the extent of endocrine dysfunction and the females. In contrast, lesions Posterior pituitary dysfunction, and in particular originating in the suprasellar region (e. Third, fourth and sixth cranial lowing pituitary surgery (when it is often transient), nerve palsies are relatively rare even with lateral but can also be seen with inltrative disorders (e. However, The diagnosis of acromegaly is conrmed by the transsphenoidal surgery remainsthe mainstayoftreat- nding of: ment for pituitary adenomas (micro or macro) causing Cushings disease, acromegaly and also for non-func-. Cortisol hypersecretion can be controlled with metyr- apone or ketoconazole (which block adrenal steroid Hormone hyposecretion biosynthesis). Bilateraladrenalectomymayberequired in patients with severe hypercortisolism refractory to Screening for hypopituitarism includes measurement medicaltherapy;however,ifradiotherapyisnotgivenin of: this setting, then the patient is at risk of developing. Thyroxine replacement is used to correct Primary hyperaldosteronism hypothyroidism. Primaryhyperaldosteronismisanimportanttreatable cause of hypertension in the young to middle-aged. Local mass effect Aetiology Although bromocriptine/cabergoline may induce rapid tumour shrinkage in cases of prolactinoma, Many cases are caused by benign aldosterone pro- surgical decompression (transsphenoidal or trans- ducing adenomas (so-called Conns adenomas), but cranial) is required in the majority of patients with bilateral adrenal hyperplasia/nodular disease is also compression of the optic chiasm in order to avoid found in a signicant number of patients. Prognosis and treatment Clinical presentation Untreated Cushing syndrome is often fatal, predom- Most cases come to light during investigation of inantly as a consequence of cardiovascular compli- hypertension or unexplained hypokalaemia. Similarly, uncontrolled acromegaly is associated with Evidence of end organ damage (e. Control of Investigation growth hormone hypersecretion restores morbidity/ Prior to investigation it is important to ensure satisfac- mortality levels to that of the general population. Screening tests are also traditionally creased mortality rate of approximately twice that of performed having withdrawn agents (e. Creatinine and electrolytes the classical picture is one of hypokalaemic alkalosis: the accompanying The adrenal glands comprise two major functional serum sodium level is typically normal to high. The cortex However, some patients with primary hyperaldos- consists of three zones: an inner zona reticularis teronism are normokalaemic at presentation. However, this should only be un- modulatory effects and is important in the mainten- dertaken under specialist supervision and not in ance of normal circulatory function. Weakness and impaired cognition virtueof its ability to blockthe actionof aldosterone at. Hyperkalaemia the anti-androgenic side effect prole of spironolac- tone) and amiloride are alternatives if spironolactone is poorly tolerated. Thereafter specic therapy is directed at the may present with menstrual disturbance (oligo/ underlying cause: amenorrhoea). In non-emergency cases consider the following: Although tuberculosis probably remains the com-. Full bloodcountnormochromic normocytic anae- and may be associated with other autoimmune glan- dular hypofunction (see autoimune polyglandular mia, neutropenia and eosinophilia are all recog- syndromes, p. Normal subjects exhibit a peak response nding on imaging, clinically evident adrenal insuf- >500nmol/l at 30min (precise thresholds depend ciency is rare in this setting. Exclusion of other associated conditions (see auto- immune polyglandular syndromes, p. Clinical presentation The clinical picture varies widely from the acutely ill Management patient in Addisonian crisis (Box 16.

T. Daro. Drexel University.