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Central blood volume order viagra professional 100 mg mastercard erectile dysfunction jet lag, in turn purchase viagra professional 50mg with mastercard erectile dysfunction and diabetes type 1, was reduced by the and the ECG is normal (Fig. What are three lines of evidence for ventilatory limitation to constriction of the renal vascular beds, which, in turn, con- this subject’s exercise? Why did arterial blood oxygen saturation fall during exer- tion of the renin-angiotensin system) to scanty urine pro- cise? Why would endurance exercise training likely increase this large amounts of sweat, and losing correspondingly large individual’s exercise capacity? Ventilatory limitation is evidenced by severe dyspnea as a next morning without correcting the salt deficit, he is likely primary symptom in exercise, falling arterial blood oxy- to have further difficulties in the heat. Even if the medical genation, and exercise termination at relatively low heart officer has guessed incorrectly about the patient’s salt bal- rate. Arterial blood oxygen saturation fell during exercise be- fluid intake should be able to excrete any excess salt result- cause increased cardiac output (increased pulmonary blood ing from the treatment. Hyponatremia can produce symptoms similar to the pa- tent (a result of increased skeletal muscle oxygen extrac- tient’s symptoms. However, the medical officer was able to tion) increase demands for oxygenation in lungs with inade- exclude hyponatremia (although not necessarily some de- quate diffusing capacity. Exhaustion occurred before a maximal heart rate was Giving a hyponatremic patient large volumes of fluid with- reached because lung disease creates severe dyspnea even out an equivalent of salt (which would have been a reason- in mild exercise. The pulse pressure rose during exercise because sympa- thetic stimulation and enhanced venous return increase the would worsen the hyponatremia, perhaps to a dangerous stroke volume at constant arterial compliance. Endurance exercise training would have little effect on any Reference aspect of lung function. Clinical complications of body fluid and elec- adaptations within exercising muscle that would increase trolyte balance. Body Fluid Bal- muscle oxidative capacity and reduce lactic acid production. Boca Raton, FL: CRC Press, By reducing the ventilatory demands of exercise, these 1996;297–317. PART IX Endocrine Physiology CHAPTER Endocrine Control Mechanisms Daniel E. Hormones are chemical substances, involved in cell-to-cell transported in the bloodstream bound to carrier proteins, communication, that promote the maintenance of home- whereas most peptide and protein hormones are soluble in ostasis. Steroid hormones and thyroid hormones are generally docrine abnormalities. The word “hormone” is derived gan systems by a group of specialized chemical substances from the Greek hormaein, which means to “excite” or to “stir called hormones. Certain endocrine disease nate a variety of different physiological processes. The states, such as diabetes mellitus, thyroid disorders, and re- processes that hormones regulate fall into four areas: (1) the productive disorders, are fairly common in the general pop- digestion, utilization, and storage of nutrients; (2) growth ulation; therefore, it is likely that they will be encountered and development; (3) ion and water balance; and (4) repro- repeatedly in the practice of medicine. In addition, because hormones either directly or indi- rectly affect virtually every cell or tissue in the body, a num- ber of other prominent diseases not primarily classified as Hormones Regulate and endocrine diseases may have an important endocrine com- Coordinate Many Functions ponent. Atherosclerosis, certain forms of cancer, and even certain psychiatric disorders are examples of conditions in It is difficult to describe hormones in absolute terms. As a which an endocrine disturbance may contribute to the pro- working definition, however, it can be said that hormones gression or severity of disease. They Feedback Regulation Is an Important are highly potent, specialized, organic molecules produced Part of Endocrine Function by endocrine cells in response to specific stimuli and exert The endocrine system, like many other physiological sys- their actions on specific target cells. The mecha- equipped with receptors that bind hormones with high nism is usually negative feedback, although a few positive affinity and specificity; when bound, they initiate charac- feedback mechanisms are known.

Answer D: A lesion in area 44 (the pars opercularis) that spreads will affect the lower portions of the precentral gyrus in which the 26 purchase viagra professional 50mg mastercard bisoprolol causes erectile dysfunction. Answer E: The uncus is a small elevation at the rostral and me- face is represented generic 100mg viagra professional mastercard impotence exercises. This will result in weakness of facial muscles, dial aspect of the parahippocampal gyrus adjacent to the crus cere- accompanied by other cranial nerve deficits. In addition to the catastrophic effect of de- hearing and vision are far separated from area 44. Also, a lesion in cerebration, herniation of the uncus may also affect corticospinal the primary auditory cortex will not result in a hearing loss in one and corticonuclear (corticobulbar) fibers in the crus cerebri and ear. The hand area of the sensory cortex and the upper extremity the root of the oculomotor nerve. None of the other areas of the area of the motor cortex are not adjacent to Brodmann area 44. Answer D: The superficial middle cerebral vein is located on the sist of the parieto-occipital and calcarine branches; the latter being surface of the cerebral hemisphere in the immediate vicinity of the located in the calcarine sulcus and a primary blood supply to the lateral sulcus and, of the choices, is the most likely candidate. M3 and M4 segments of the middle cerebral deep middle cerebral vein is located on the surface of the insular are located, respectively, on the inner aspect of the frontal, pari- lobe. The inferior sagittal sinus primarily drains the medial aspect etal, and temporal opercula and on the lateral aspect of the cere- 260 Q & A’s: A Sampling of Study and Review Questions with Explained Answers bral hemisphere. Answer E: Cerebrospinal fluid in the ventricles, and throughout located just distal to the posterior communicating–posterior cere- the subarachnoid space, appears very white in T2-weighted MRI bral intersection and gives rise to medial and lateral posterior images. Structures located in, or traversing the subarachnoid choroidal and to thalamogeniculate arteries. The A1 segment is lo- space (such as vessels or cranial nerve roots, including the oculo- cated between the internal carotid and anterior communicating motor nerve) appear grey to black against a white background. Answer B: The glomus choroideum is found in the atrium of the T1-weighted MRI images. This part of the choroid plexus is rostrally contin- obvious parts of the subarachnoid space, appear black. Changes in uous with that in the body of the lateral ventricle and continuous ventricular shape (i. The roof of the sulci, or even subarachnoid space, most likely represent a poten- third ventricle has a small portion of choroid plexus that is contin- tially serious clinical issue. Answer E: Patients who experience rupture of an intracranial aneurysm frequently complain of an intense, sudden headache 29. Answer E: Trauma is the most common cause of subarachnoid (“the most horrible headache I have ever had”). The most common cause of spontaneous (also subarachnoid space will appear white to very white on CT. This called nontraumatic) SAH is bleeding from a ruptured aneurysm will contrast with the medium grey of the brain and the black of (about 75% of all spontaneous cases). The degree of white nous malformation (AVM) is an infrequent cause of SAH (about may vary somewhat, based on the relative concentration of blood, 5% of cases), and bleeding from brain tumors into the subarach- from very white (concentrated blood) to white (mostly blood, noid space is rare. Meningiomas are usually slow-growing tumors some CSF), to very light grey (mixture of blood and CSF). Answer D: The prepontine cistern is located external to the olivary sulcus of the medulla immediately (and laterally) adjacent basilar pons and contains the abducens nerve, basilar artery, ori- to the pyramid.

This is hemody- the aorta becomes less compliant buy viagra professional 50mg on-line facts on erectile dysfunction, and aortic pressure rises namic pressure buy viagra professional 100 mg line impotence 23 year old, produced by contractions of the heart and more for a given increase in aortic volume. The next section de- of the legs, the volume of the veins expands much more scribes a third form of energy, hydrostatic pressure, derived than that of the arteries. Mean Arterial Pressure Depends on Cardiac A Column of Fluid Exerts Hydrostatic Pressure Output and Systemic Vascular Resistance Fluid standing in a container exerts pressure proportional A simple model is useful in seeing how the pressures, flows to the height of the fluid above it. The pressure at a given and volumes are established in the cardiovascular system. This hydro- propels fluid into stiff tubing that is of a large enough di- static pressure is caused by the force of gravity acting on ameter to offer little resistance to flow. When a person stands, blood pressure is greater circuit is a narrowing or stenosis of the tubing where almost in the vessels of the legs than in analogous vessels in the all of the resistance to blood flow is located. The tubing arms because hydrostatic pressure is added to hemody- downstream from the stenosis is 20 times more compliant namic pressure. The hydrostatic pressure difference is than the tubing upstream from the stenosis. It has the same proportional to the height of the column of blood be- diameter as the upstream tubing and also offers almost no tween the arms and legs. Two conventions are observed when measuring blood First imagine that the pump is turned off and the tub- pressure. First, ambient atmospheric pressure is used as a zero ing is completely collapsed. At this point, enough fluid reference, so the mean arterial pressure is actually about 93 is infused into the circuit to fill all of the tubing and just mm Hg above atmospheric pressure. Second, all cardiovascu- begin to stretch the walls of the upstream and down- lar pressures are referred to the level of the heart. Once the infused fluid comes to rest in- into account the fact that pressures vary depending on posi- side the tubing, the pressure inside the tubing is the tion because of the addition of hydrostatic to hemodynamic same throughout because the pump is not adding energy pressure. The pressure inside sure is discussed, the term hydrostatic pressure is used to mean the tubing is the pressure needed to “inflate” or fill the hemodynamic plus hydrostatic pressure. The pressure outside the tub- strictly correct, it is the conventional usage. Because the trans- mural pressure is the same throughout, and the left side of the circuit is made up of more compliant tubing, its Transmural Pressure Stretches Blood Vessels volume is larger than the volume of the right side (see in Proportion to Their Compliance equation 6). Thus far, we have discussed pressure and flow in the car- Imagine that the pump turns one cycle and shifts a small diovascular system as if blood vessels were rigid tubes. But volume of fluid from the high-compliance tubing to the blood vessels are elastic, and they expand when the blood low-compliance tubing. The degree to which a distensi- has little effect on pressure because of its high compliance. The pressure difference between the right and left pressure inside and outside a blood vessel: side initiates flow from right to left. With only one stroke of the pump, the pressures on the two sides of the stenosis PTM Pinside Poutside (5) soon equalize as the volumes return to their resting values. Compliance (C) is defined by the equation: If the pump is turned on and left on, net volume is C V/ PTM (6) transferred from left to right until the pump has created CHAPTER 12 An Overview of the Circulation and Hemodynamics 215 Flow difference between point A (PA) and point D (PD) divided High-compliance, Low-compliance, low-resistance by the resistance (R) to flow (see equation 1): low-resistance tubing D A tubing Rate of pump transfer of volume from D to A Q (PA – PD)/R (7) We can think about the coupling of the output of the left heart to the flow through the systemic circulation in an anal- C B ogous fashion.

Muscular System © The McGraw−Hill Anatomy quality viagra professional 50 mg erectile dysfunction medication samples, Sixth Edition Companies buy 100 mg viagra professional erectile dysfunction doctors kansas city, 2001 Chapter 9 Muscular System 285 Muscles of the Foot With the exception of one additional intrinsic muscle, the ex- tensor digitorum brevis (fig. The functions of the muscles of the foot are different, however, because the foot is adapted to provide support while bearing body weight rather than to grasp objects. The muscles function either to move the toes or to support the arches of the foot through their contraction. Because of their complexity, the muscles of the foot will be presented only in il- lustrations (see figs. List all the muscles that either originate from or insert on the scapula. On the basis of function, categorize the muscles of the upper extremity as flexors, extensors, abductors, adduc- tors, or rotators. Which muscles of the lower extremity span two joints, and therefore have two different actions? CLINICAL CONSIDERATIONS Compared to the other systems of the body, the muscular system is extremely durable. If properly conditioned, the muscles of the body can adequately serve a person for a lifetime. Muscles are ca- pable of doing incredible amounts of work; through exercise, they can become even stronger. The flexor digitorum longus Evaluation of Muscle Condition works over several joints, flexing the joints in four of the digits and assisting in plantar flexing the ankle joint and inverting The clinical symptoms of muscle diseases include weakness, loss the foot. The most obvious diagnos- The tibialis posterior muscle is located deep to the soleus tic procedure is a clinical examination of the patient. Its distal tendon passes be- this, it may be necessary to test muscle function using elec- hind the medial malleolus and inserts on the plantar surfaces of tromyography (EMG) to measure conduction rates and motor the navicular, cuneiform, and cuboid bones, and the second, unit activity within a muscle. A biopsy is perhaps the rior plantar flexes the ankle joint, inverts the foot, and lends sup- most definitive diagnostic tool. Muscular System © The McGraw−Hill Anatomy, Sixth Edition Companies, 2001 286 Unit 4 Support and Movement TABLE 9. Plantaris Lateral supracondylar ridge of Calcaneus Plantar flexes foot at ankle Tibial n. Obviously, overuse or disease will cause a change der may be either inborn or acquired. The immediate effect of overexertion on mus- A condition called rigor mortis (rigidity of death) affects cle tissue is the accumulation of lactic acid, which results in fa- skeletal muscle tissue several hours after death, as depletion of tigue and soreness. Excessive contraction of a muscle can also ATP within the fibers causes stiffness of the joints. This is similar damage the fibers or associated connective tissue, resulting in a to physiological contracture, in which muscles become incapable of strained muscle. A cramp within a muscle is an involuntary, painful, pro- When skeletal muscles are not contracted, either because longed contraction. Cramps can occur while muscles are in use the motor nerve supply is blocked or because the limb is immobi- or at rest. They may result from general dehydration, deficiencies of is resumed, as after a healed fracture, but tissue death is in- calcium or oxygen, or from excessive stimulation of the motor evitable if the nerves cannot be stimulated. Muscular System © The McGraw−Hill Anatomy, Sixth Edition Companies, 2001 Chapter 9 Muscular System 287 FIGURE 9. The fibers in healthy muscle tissue increase in size, or hy- column, where there are extensive aponeuroses. There are sev- myofibrils, accompanied by a strengthening of the associated eral kinds of muscular dystrophy, none of whose etiology is com- connective tissue.