Chapter 19 The Cardiovascular System/ Blood Vessels/ Blood/ clinical questions

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Chapter 19 The Cardiovascular System: Blood Vessels Clinical questions

1) Describe the effect of hypovolemic shock on the blood vessels and the heart.

Answer: Hypovolemic shock causes blood vessels to constrict to increase venous return and maintain pressure. Heart rate increases to compensate for loss of blood pressure and to maintain cardiac output. If volume loss continues, pressure eventually drops sharply and the shock becomes irreversible, leading to death.

2) Atherosclerosis is a progressive disease of blood vessels that is responsible for millions of deaths each year. Describe the disease process, noting the involvement of specific cell/tissue types and molecules.

Answer: The disease process involves several stages and usually affects the aorta and coronary arteries. The initial event involves damage to the tunica intima caused by bloodborne chemicals or physical factors such as a blow or infection. Injured endothelial cells release chemicals that increase the uptake by the endothelium of fats, LDLs, and cholesterol. This eventually attracts macrophages that ingest the oxidized fats and, along with smooth muscle cells from the tunica media, transform into foam cells. Foam cells become fatty streaks, which, along with collagen and elastin fibers secreted by smooth muscle cells, form atherosclerotic plaques. These protrude into the lumen and narrow the blood vessels.

3) A woman in her early 50s appeared at a walk-in clinic, complaining of aching pain in her right leg following a fall. Visual examination revealed that the medial aspect of that leg was red and swollen. A diagnosis of phlebitis was made. What is phlebitis, and what more serious condition may result if proper healing does not occur?

Answer: Phlebitis is an inflammation of a vein accompanied by painful throbbing and redness of the skin over the inflamed vessel. Thrombophlebitis (clot formation) can result if proper healing does not occur. The danger in thrombophlebitis is the possibility that a clot could detach and form an embolus.

4) For each of the following situations, describe the anticipated effect on blood pressure and the physiological basis of the response: (1) a high-salt diet, (2) a blow on the head that damages (disables) the vasomotor center, (3) an attack by a mugger, and (4) a hypothalamic tumor resulting in excess ADH production.

Answer: (1) A high-salt diet causes increased sodium in the blood, which increases total extracellular fluid volume. This leads to increased blood volume and blood pressure. (2) Damage to the vasomotor center will cause a loss of vasomotor tone and a drop in blood pressure because the vasomotor center is the integrating center for blood pressure control. (3) During the mugger attack, blood pressure would increase due to sympathetic nervous system stimulation (the fight-or-flight response) triggered by the hypothalamus. (4) Excess ADH production would cause an increase in blood pressure through increased water retention and therefore increased blood volume. ADH also stimulates vasoconstriction.

5) Mrs. Gray, a 50-year-old mother of seven children, is complaining of dull, aching pains in her legs. She reports that they have been getting progressively worse since the birth of her last child. During her physical examination, numerous varicosities are seen in both legs. How are varicosities recognized? What veins are most likely involved? What pathologic changes have occurred in these veins, and what is the most likely cause in this patient's case?

Answer: Varicosities are recognized by the enlargement of the veins. Superficial veins are most likely involved because they have little support from surrounding tissues. The veins have become tortuous and dilated because of incompetent valves that allow the blood to pool, stretching the vein walls. The likely cause in this patient's case is her pregnancies, because the enlarged uterus exerts downward pressure on groin vessels, restricting return blood flow to the heart.

6) Mr. Wilson is a 45-year-old stockbroker with essential hypertension. He is African American, obese, and he smokes 2-3 packs of cigarettes daily. What risk factors for hypertension are typified by Mr. Wilson? What steps should be taken to treat Mr. Wilson, and what lifestyle changes should he make? What complications are likely if corrective steps are not taken?

Answer: The risk factors are obesity, race, a high-stress job, and smoking. Mr. Wilson should lose weight, reduce salt intake, quit smoking, and try to reduce his stress level, perhaps by relaxation training. Medical intervention could include treatment with diuretics, beta blockers, calcium channel blockers, and angiotensin converting enzyme inhibitors. Complications could include atherosclerosis, heart failure, renal failure, and stroke.

7) A pregnant patient comes into a clinic and asks about a small dark bulge that is becoming more apparent on her leg. What is it and what caused it?

Answer: The patient is getting a varicose vein. Due to the growing fetus putting downward pressure on the vessels of the groin and restricting the return of blood to the heart, the valves in the peripheral veins begin to fail. This causes blood pooling, which enlarges these veins and puts additional strain on other peripheral vein valves down the line.

8) At the battle of Shiloh in the American Civil War, Confederate General A. S. Johnston was killed when he was shot in the thigh. Witnesses reported that he bled to death almost before he realized that he was wounded. Which blood vessel was most likely to have been injured? Why is a tourniquet usually ineffective in stopping the bleeding from this wound?

Answer: The wound severed his femoral artery, the largest artery serving the lower limb. A tourniquet may be ineffective because it is a high-pressure, deep artery with a large diameter. It is therefore difficult to exert enough pressure through the thigh muscles to stop the bleeding.

9) A patient lost a lot of blood during surgery and his blood pressure dropped from 120/80 to 90/50. Describe how the kidneys respond to this change in blood pressure.

Answer: When arterial blood pressure declines, special cells in the kidneys release the enzyme renin into the blood. Renin triggers a series of enzymatic reactions that produce angiotensin II, which is a potent vasoconstrictor. Angiotensin causes an increase in systemic blood pressure, and increases the rate of blood delivery to the kidneys and renal perfusion. It also stimulates the adrenal cortex to secrete aldosterone, a hormone that enhances renal reabsorption of sodium, and prods the posterior pituitary to release ADH, which promotes more water reabsorption. As sodium moves into the bloodstream, water follows; thus both blood volume and blood pressure rise.

10) A patient has an 80% blockage of his left anterior descending coronary artery. Describe what occurs in terms of myocardial oxygen supply and demand if his sympathetic nervous system is stimulated.

Answer: When the sympathetic nervous system is stimulated there is increased myocardial contractility, which increases cardiac output and blood flow to active muscles. This increases the demand for oxygen to the cells. The coronary artery is a major blood vessel of the heart. When the demand for myocardial oxygen exceeds the ability of the coronary arteries to supply it, death of myocardial tissue can occur.

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