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At the end of about a 4-month lifetime buy dutasteride from india hair loss in men vitamins, old erythrocytes are engulfed by macrophages cheap dutasteride 0.5 mg amex hair loss 3 month old baby. Their hemoglobin discount 0.5 mg dutasteride otc hair loss cure uk, including iron, is recycled while generating the diagnostic waste product bilirubin. Excess bilirubin or an inability to process the bilirubin due to liver or gallbladder disease causes jaundice. Leukocytes are classified morphologically as granulocytes (eosinophils, basophils, and neutrophils) and agranulocytes (monocytes and lymphocytes). Leukocytes defend the body against infection using phagocytosis and various antimicrobial weapons, release mediators to control inflammation, and contribute to wound healing. Hematopoiesis is the development of circulating blood cells from the uncommitted hematopoietic stem cell of bone marrow. Immature cells differentiate along cell lineages into mature cells promoted by hematopoietins and other cytokines. Erythropoietin is a hormone produced by the kidney and in response to low blood O and promotes2 erythropoiesis in bone marrow. Patients on dialysis often require erythropoietin intake to maintain a normal hematocrit (Hct). Thrombocytes (platelets) are irregularly shaped, small, anuclear, cell-derived structures that, together with plasma proteins, control blood clotting and promote wound healing. Blood coagulation involves the fast formation of a weak platelet plug of aggregated platelets, which is expanded and stabilized into a more robust plug made of cells, platelets, and insoluble fibrin 2+ molecules. Endothelial cells, blood coagulation factors, Ca, and mediators released by platelets, control the coagulation cascade. Other routinely performed blood tests include blood viscosity, specific gravity, serum protein electrophoresis, erythrocyte sedimentation rate, coagulation tests (e. For blood transfusions, donor and recipient blood must be compatible to avoid agglutination between erythrocyte-associated A, B, and Rh antigens and anti-A, anti-B, and anti-Rh antibodies. Which of the following would be expected to contain relatively high numbers of functional hematopoietic progenitor cells? Umbilical cord blood, derived from the circulating blood of newborn infants, possesses high levels of hematopoietic progenitors. The spleens of adult humans function as a hematopoietic organ only in certain disease states, such as leukemia. The granulocyte group consists of neutrophils, eosinophils, and basophils, while monocytes/macrophages and lymphocytes (B cells and T cells) belong to the category of agranulocytes. Polycythemia vera is a hereditary neoplastic bone marrow disorder characterized by abnormally high red blood cell production. The steady state concentration of a substance in serum can provide additional information to confirm the diagnosis of the patient with polycythemia vera. This is in contrast to patients with secondary polycythemia, which is caused by respiratory conditions like emphysema that stimulate erythrocyte production. Its steady state condition in serum can provide useful information in the assessment of various anemic and polycythemic conditions. A woman nursing twins recently born by a complicated caesarian section The correct answer is D. To avoid hemorrhagic shock, the victim is treated with saline, which equally diluted all blood components. On the other hand, all other patients are likely to suffer from iron deficiency anemia due to chronic blood loss or increased iron demand. Blood loss during a complicated caesarian section and increased iron requirement for lactation might cause anemia for the woman with the twins. She felt well prepared by the nurse to take care of the baby at home, and breast-feeding was less of a problem than anticipated. At the February meeting, the baby looked very pale and bluish; the mother looked very tired and said that the baby cries a lot. A smear of the baby’s blood revealed severe hypochromic microcytic erythrocytes with marked anisocytosis and poikilocytosis. The pediatrician became concerned and was suspicious about the presence of a blood disorder, possibly thalassemia, a condition in which insufficient Hgb is formed. The result of a genetic analysis confirmed the diagnosis of beta-thalassemia major. Since low iron is the most common reason for anemia of babies, it is necessary to closely monitor Hgb values in the near future. The major form of beta-thalassemia leads to a significant deficiency in the beta chain production of Hgb so that there is little or no Hgb A present. As a consequence, Hgb A2 and Hgb F are elevated and for a short time substitute for the Hgb A loss. However, with decreasing Hgb F, starting soon after birth, the baby becomes hypoxic (pale), which stimulates erythropoietin production. Erythropoietin stimulates intramedullary, and eventually extramedullary, hematopoiesis. This leads to target cells with dense center and pale rim, and generally to a cell population of unequal size (anisocytosis), abnormal shape (poikilocytosis), and cell breakage (schistocytes). Apply the roles of both noncellular and cellular components of innate immunity in maintaining body homeostasis. Explain how the adaptive immune system achieves its three main features: specificity, diversity, and memory. Describe the mechanisms for both exogenous and endogenous antigen presentation in cell-mediated immunity. Identify three ways that the five classes of antibodies work to eliminate antigens. Describe the interaction among the immune, neuronal, and hormonal systems in maintaining homeostasis. In later chapters, you will learn about other systems, such as the cardiovascular, respiratory, renal, and endocrine systems. By contrast, you will see in this chapter that the immune system is made up of a wide variety of disease-fighting cells found throughout the body in the plasma, lymph, tissues, and the various organs. The immune system is essential in our survival and the maintenance of optimal health. The immune system protects the body with a set of remarkable molecules called antibodies that can recognize an infinite range of foreign invaders known as pathogens (e. Immunology is the study of the functional process in which foreign matter (living and nonliving) is either destroyed or rendered harmless by the body’s defense system. The functional role of the immune defense system is to (1) protect the body against infection and pathogens (bacteria, fungi, viruses, parasites, and other microbes), (2) neutralize and/or destroy foreign matter, and (3) function as an immune surveillance system (screening and neutralizing malignant cells). Immunologic disorders (autoimmune diseases, hypersensitivities, and immune deficiency) result from malfunctions or inappropriate responses of the immune system. Immunology has contributed to great advances in medicine following Louis Pasteur’s theory that microorganisms are the cause of infection and his role in the understanding that vaccination prevents infectious disease. The aim of this chapter is to present basic components of the immune system and their roles in organ function and homeostasis. The immune system detects a wide variety of pathogenic agents, from bacteria to viruses to parasitic worms.
For this reason buy discount dutasteride 0.5mg hair loss years after chemo, diastolic pressure drops to only about 80 mm Hg in the aorta as compared with near zero in the ventricles 0.5 mg dutasteride free shipping hair loss updates. Although there are many more arterioles than arteries in the cardiovascular system (resistances in parallel) proven 0.5 mg dutasteride hair loss in men vest, this large pressure drop indicates that their reduction in individual size dominates over the addition of parallel vessels. Similarly, although individual capillaries are very small (~10 μm), so many of these lie in parallel that resistance across the capillaries is actually lower than that across the arterioles; hence, the pressure drop across the capillary segment of the circulation is less than that across the arterioles. Pressures within the arteries of the pulmonary circulation are not the same as those in the systemic circulation. Because the outputs of the right and left heart are the same, the low pressure in the pulmonary circulation must indicate, according to Poiseuille’s law, that vascular resistance is much lower in the pulmonary circulation than in all the organs combined that make up the systemic circulation. Arteries must grow larger and new arteries formed (arteriogenesis) and new capillaries must increase in numbers as well (angiogenesis). The process of arteriogenesis is currently the subject of intense multidisciplinary research. Insight into the mechanisms for stimulation of vascular growth hold the promise of development of methods of a circumventing damage to tissue below an occluded artery by stimulation of new collateral arterial growth through and around tissue downstream from the occlusion. Currently, the term angiogenesis is mainly applied to the development of collateral circulation around subacute, or slowly developing, arterial occlusions. In occlusive disease, only angiogenesis provides the means to fix flow deficits caused by an arterial occlusion. Angiogenesis requires both the enlargement of small, preexisting collateral arterial vessels and an increase in their length. Consequently, arteriogenesis is a process of active growth not passive distention of existing vessels. The pressure gradient between the upstream high pressure origin of the collateral above the occlusion and the downstream low pressure postocclusion zone initiates a marked increase in blood flow through the collateral vessel. It is now well established that the initiating stimulant for angiogenesis is the increased fluid shear stress on arterial endothelial cells that accompanies the increased blood flow. Because there is no direct cell-to-cell contact between the endothelial and smooth muscle layers in arteries, the signal from this mechanical force on the intima to underlying cells in the arterial wall has to be through a diffusible molecule. Circulating monocytes, either directly or by activating arterial wall macrophages, are known to stimulate arterial wall secretion of chemokines, growth factors, and proteases that can be involved in arterial wall growth and remodeling. These findings indicate that the immune system in the body could play a key role in arteriogenesis. Pressure is created within the atria and ventricles of the heart by contraction of the cardiac muscle. The directional opening of valves, which prevent back flow between chambers, ensures forward movement of blood through the heart. Capillaries are the primary site of transport between blood and the extracellular fluid. Altering vascular smooth muscle contraction changes blood vessel radius and hemodynamic properties. Vascular resistance is inversely proportional to the internal radius of the blood vessel. The volume contained within any vascular segment is a function of transmural pressure and the compliance of the vascular wall. Transmural pressure in blood vessels produces wall tension and stress that must be overcome for the vessel to contract. Blood flow and pressure throughout the vascular system is created in accordance with the principles of Poiseuille’s law; flow is proportional to the pressure gradient between points in the circulation but inversely proportional to vascular resistance. The velocity of blood flow in an artery affects lateral pressure and inner wall shear stress in arteries as well as transport across the capillary wall. The hemodynamic profile in the cardiovascular system is the result of the combined effects of all the relationships and laws governing the containment and movement of blood in the cardiovascular system. Which of the following will exacerbate the pooling of blood that occurs in veins in the lower extremities of a patient when he or she assumes an upright position? Activation of α-adrenergic receptors on veins by the sympathetic nervous system B. Administration of the antianginal drug, nitroglycerin, which directly dilates veins more than arteries C. Administration of the emergency antihypertensive agent sodium nitroprusside, which directly dilates arteries more than veins D. Placing the patient in supine position with his or her legs up The correct answer is B. Blood preferentially pools in the veins versus the arteries under the influence of gravity because veins are more compliant than arteries. Contraction of vascular smooth muscle reduces vascular compliance, whereas relaxation of vascular smooth muscle increases compliance. For this reason, nitroglycerin will increase the amount of blood pooling in veins in a patient when he or she stands upright. This is a contributing factor in postural hypotension that often occurs in patients taking nitroglycerin for angina or heart failure. The enhancement of pooling temporarily causes a reduction in cardiac output severe enough to reduce arterial pressure and cause fainting. Drugs that predominantly relax arteries over veins do not cause much blood pooling upon standing and are generally not associated with postural hypotension. Indeed, contraction of veins by activation of the sympathetic nervous system is the body’s natural mechanism for preventing postural hypotension. Support stockings, mechanical compression devices used on the legs after surgery, and the lower body compression suits worn by jet fighter pilots are ways in which application of external compression on the veins counteracts venous pooling in the lower extremities. Laying a patient horizontally with his or her legs up does take advantage of the effects of gravity on blood volume in the veins, except in this case gravity helps drain blood from the legs and send it to the heart. A patient has a significantly reduced blood hematocrit as the result of a chronic bleeding ulcer. A heart murmur during systole can be heard with a stethoscope over the patient’s chest. Blood viscosity is significantly related to blood hematocrit; blood with a low hematocrit has low viscosity. As reflected in the Reynolds number, turbulence is most likely to occur with low viscosity fluid at high flow velocity in vessels with large internal diameters. This corresponds to the situation in the aorta during systole in a patient with an abnormally low hematocrit. Although the decreased hematocrit decreases resistance to flow through any segment of the arterial system, this effect in arterioles is unrelated to any murmur heard from the heart. Which of the following describes the properties of an aortic segment exposed to a transmural pressure of 200 mm Hg compared to the same segment exposed to a transmural pressure of 100 mm Hg? Re: Arteries are stiffer (reduced compliance) at very low and very high pressures. An aortic segment exposed to an internal net pressure of 200 mm Hg is distended to a place on its volume versus pressure curve where the aorta is stiffer, or less compliant. Tension = P × r is higher in cylindrical tubes like the aorta at high transmural pressures and large radii. In the segment exposed to 200 mm Hg versus 100 mm Hg not only is distending pressure higher but the aorta will be distended to a slightly larger radius and therefore that will also increase wall tension.
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Most are vascular in origin order dutasteride 0.5 mg visa hair loss in men quote, but they can result from trauma generic dutasteride 0.5mg mastercard hair loss finasteride, anoxia cheap 0.5 mg dutasteride fast delivery hair loss restoration, carbon monoxide poisoning, cardiac arrest, and exsanguination (Fig. This defect occurs with homonymous hemianopia, caused by lesions in the anterior portion of the postchiasmal pathway. C Axons from these cells cross the retina as E the nerve fiber layer and become the optic F nerve. The arrangement of these fibers determines the visual-field defects seen G in glaucoma and other optic nerve lesions. The optic tracts begin posterior to the chiasm and connect to the lateral geniculate body on the posterior of the thalamus. Diagram of the visual pathway with synapse to cells that then connect to the sites of nerve fiber damage and corresponding occipital cortex (area 17) via optic visual fields produced by this damage. A, Optic radiations in the temporal and parietal nerve: blindness on involved side with normal lobes. E, characteristically seen in neuro- Posterior optic tract, external geniculate ganglion, posterior limb of internal capsule: contralateral ophthalmologic disorders? F, Optic radiation, anterior loop in these patients can often be used to temporal lobe: incongruous contralateral locate very precisely the area of the homonymoushemianopiaorsuperiorquadrantopia. H, Optic radiation in parietal lobe: contralateral homonymous hemianopia, may be mildly incongruous, minimal macular sparing. Describe the visual-field defect in radiation inposteriorparietal lobeandoccipitallobe: Fig. J, Midportion of calcarine cortex: contralateral congruous homonymous This is a bitemporal hemianopia. K, Tipofoccipital hemianopia because they damage the lobe: contralateral congruous homonymous crossing nasal nerve fibers. L, Anterior tip of calcarine fissure: contralateral loss of temporal crescent with this area include pituitary tumors, otherwise normal visual fields. In addition, the chiasm may be damaged by trauma (typically causing a complete bitemporal hemianopia), demyelinating disease, and inflammatory diseases such as sarcoidosis, and rarely, ischemia. True binasal hemianopias are rare, but they are never a result of chiasmal compression. They may be due to pressure upon the temporal aspect of the optic nerve and the anterior angle of the chiasm or near the optic canal. Causes include aneurysm, tumors such as pituitary adenomas, and vascular infarction. Where would you expect the lesion causing an homonymous hemianopia without optic atrophy to be located? Any lesion anterior to the lateral geniculate body would cause the ganglion axon cells to degenerate. Patients with isolated retrochiasmatic lesions do not have decreased visual acuity unless the lesions are bilateral, and then the visual acuity should be equal. This can be supported with color plate abnormalities and a relative afferent pupillary defect. Also examine the patient for optic disc abnormalities such as pallor, cupping, and drusen. This is a cecocentral lesion defined as a lesion involving both the blind spot and the macular area (to the 25-degree circle). Four primary causes are typically cited: dominant optic atrophy, Leber’s optic atrophy, toxic/nutritional optic Figure 6-8. A ‘‘pie-in-the-sky’’ lesion is a homonymous quadrantanopia involving the superior quadrant. The term indicates a lesion in the optic radiations through the temporal lobe, but similar defects can be seen with occipital lobe lesions as well. A ‘‘pie-on-the-floor’’ lesion is a homonymous quadrantanopia involving the inferior quadrant. These patients often have coexistent spasticity of conjugate gaze (tonic deviation of eyes opposite to the side of the lesion when attempting Bell’s phenomenon) and optokinetic asymmetry (diminished or absent response with rotation of optokinetic objects toward the side of the lesion). Congruous right superior homonymous quadrantanopia following left temporal lobectomy for epilepsy. A junctional scotoma is a unilateral central scotoma associated with a contralateral superior temporal field defect. Thus, in a patient that comes in with poor vision in one eye, it is very important to check the contralateral visual field for superior temporal field loss. Inferonasal retina fibers cross in the chiasm, passing into the contralateral optic nerve (Willebrand’s knee). These patients have decreased visual acuity and a relative afferent visual defect. Mass lesions of the optic tract are usually large enough to compromise the optic nerve and chiasm as well. Glaucoma is a disease characterized by loss of retinal ganglion cells with characteristic optic nerve findings. With damage to the nerve bundles, the classic findings include a nasal step, an arcuate defect within 15 degrees of fixation (also known as a Bjerrum defect), or a Siedel scotoma (a comma- shaped extension of the blind spot; Fig. Such a defect obeys the horizontal midline (in contrast to neurologic field defects, which obey the vertical midline). The exam of the optic nerve is helpful in making the diagnosis in less clear cases. If there the patient has clear optic nerve damage and corresponding visual-field defects, one can make the diagnosis, but the baseline field needs to be repeated because of the general tendency of people to improve after taking the test several times. Persons with glaucoma tend to have more variable visual fields than normal subjects; thus, a single visual field showing worsening should be confirmed with a repeat field. One study concluded that to be certain of progression, one needs a minimum of 5 years of annual visual fields. Ongoing research is trying to improve our ability to determine which patients are progressing. Severe glaucoma, retinitis pigmentosa, panretinal photocoagulation, vitamin A deficiency, other retinal and/or choroidal diseases affect the peripheral retina selectively. Aphakic patients may have a prominent ring scotoma from lens-induced magnification of the central field. Functional visual loss from hysteria or malingering may reveal a ring scotoma on visual-field testing. A Goldmann visual field may be helpful in this situation, as spiraling where an isopter of greater luminance overlaps one that is dimmer can rule out organic disease (Fig. The right eye shows a fatigue field in which a star-shaped interlacing field results from testing opposite ends of the various meridians. What is the differential diagnosis of general depression of the field without localized field defects? This is a general sign without diagnostic value, but can be an indication of glaucoma, media opacities, small pupils, refractive error, and/or an inexperienced or inattentive patient. An altitudinal defect can be seen with a hemibranch artery or vein occlusion (Fig.