Chapter 11 - Circulatory System Flashcards
The epicardium is one of the three layers of the heart. It is
(A) continuous with the endocardium.
(B) also known as the visceral pericardium.
(C) composed of modified cardiac muscle
cells.
(D) capable of increasing intraventricular pressure.
(E) capable of decreasing the rate of contraction.
B. The pericardium is a fibroserous sac that encloses the heart. The innermost layer of the pericardium, the epicardium, is also known as the visceral pericardium (see Chapter 1 1 I A 1).
The atrial muscle of the heart produces a hormone that (A) decreases blood pressure. (B) increases blood pressure. (C) causes vasoconstriction. (D) facilitates the release of renin. (E) facilitates sodium resorption in the kidneys.
A. Atrial natriuretic peptide, which decreases blood pressure, is produced mainly by cardiac muscle cells of the right atrium. It inhibits the release of renin and causes the kidneys to decrease the resorption of sodium and water (see Chapter 1 1 I A 1 b).
The generation of impulses in the normal heart is the responsibility ofwhich ofthe fol lowing structures? (A) Atrioventricular (AV) node (B) AV bundle of His (C) Sympathetic nerves (D) Sinoatrial (SA) node (E) Purkinje fibers
D. Impulses are generated in the sinoatrial node, which is the pacemaker of the heart. They are then conducted to the AV node. The bundle of His and Purkinje fibers conduct impulses from the AV node to the cardiac muscle cells of the ventricles. Sympathetic nerves can increase the rate of the heartbeat but do not originate it (see Chapter 1 1 I A 4 a).
Metarterioles, vessels interposed between
arterioles and capillary beds:
(A) function to control blood flow into arterioles.
(B) possess a complete layer of smooth muscle cells in their tunica media.
(C) possess precapillary sphincters.
(D) receive blood from thoroughfare channels.
(E) possess valves to regulate the direction of
blood flow.
C. The proximal portion of a central channel is known as a metarteriole, whereas its distal portion is the thoroughfare channel. Blood from metarterioles may enter the capillary bed if their precapillary sphincters are relaxed. If the precapillary sphincters of metarterioles are con stricted, blood bypasses the capillary bed and flows directly into thoroughfare channels and from there into a venule (see Chapter 11 I B 1 d).
Which of the following statements concerning innervation of blood vessels is true?
(A) Vasoconstriction is controlled by parasympathetic nerve fibers.
(B) Acetylcholine acts directly on smooth muscle cells.
(C) Acetylcholine acts directly on endothelial cells.
(D) Vasodilation is controlled by sympathetic nerve fibers.
(E) Nitric oxide acts as a vasoconstrictor.
C. Acetylcholine stimulates the endothelial cells of a vessel to release nitric oxide (EDRF), which causes relaxation of smooth muscle cells. Thus, acetylcholine does not act directly on smooth muscle cells (see Chapter 1 1 I B 2).
Which of the following characteristics distinguishes somatic capillaries from visceral capillaries? (A) Presence or absence of fenestrae (B) Size of the lumen (C) Thickness of the vessel wall (D) Presence or absence of pericytes (E) Thickness of the basal lamina
A. Somatic (continuous) capillaries lack fenestrae, whereas visceral (fenestrated) capillaries are characterized by their presence. Both types of capillary possess a continuous basal lamina and are surrounded by occasional pericytes (see Chapter 1 1 I C 2).
The blood-brain barrier is thought to exist because capillaries in the central ner vous system have which of the following characteristics? (A) Discontinuous basal lamina (B) Fenestrae with diaphragms (C) Fenestrae without diaphragms (D) A few pinocytic vesicles (E) No basement membrane
D. Capillaries in the CNS are of the continuous type and thus lack fenestrae but have a continuous basal lamina. In contrast to continuous capillaries in other parts of the body, they contain only a few pinocytic vesicles; this characteristic is thought to be partly responsible for the blood-brain barrier (see Chapter 1 1 I C 2).
Which of the following statements about healthy, intact capillaries is true? (A) They control blood pressure. (B) They are lined by a simple columnar epithelium. (C) They have a smooth muscle coat. (D) They inhibit clot formation. (E) Satellite cells share their basal lamina.
D. The smooth endothelial lining of intact, healthy capillaries inhibits clot formation. Capillaries do not control blood pressure (see Chapter 11 I C 2).
A patient complains of shortness of breath even after only mild exercise. She states that she has had this condition for 2 years but recently has noticed that it has become more pronounced. Her medical history indicates that she had rheumatic fever when she was a child. Auscultation indicates an enlarged heart. What may the physician expect to find with other diagnostic tests? (A) Mitral valve stenosis (B) Tetralogy of Fallot (C) Pulmonary artery aneurysm (D) Coronary heart disease (E) Ischemic heart disease
A. A person who has had rheumatic fever as a child may develop heart valve disease later in life. Although the mitral valve is the one most commonly affected, the other valves may also be involved. The mitral valve becomes inflamed, fibrotic, and eventually incompetent or stenotic. This condition leads to respiratory hypertension and edema, which restricts respiratory function. The key is a history of rheumatic fever, because those individuals are predisposed to developing heart valve diseases (see Chapter 1 1 I A 3 Clinical Considerations).
Diagnostic tests for ischemic heart disease usually reveal
(A) malformed heart valves.
(B) atherosclerosis of coronary arteries.
(C) irregular heartbeat.
(D) faulty SA valve.
(E) arteriosclerosis of coronary arteries.
B. Diagnostic tests for ischemic heart disease reveal atherosclerosis of the coronary vessels. Over time, excessive plaque composed of cholesterol and fats is layered beneath the intima of these vessels, thus restricting blood flow to the myocardium of the heart, leading to angina pectoris, an infarction, or perhaps sudden death (see Chapter 1 1 I B 1 Clinical Considerations).
Vasa vasorum function in away that is similar to (A) AV valves. (B) semilunar valves. (C) coronary arteries. (D) elastic arteries. (E) metarterioles.
C. Vasa vasorum are the small blood vessels that serve the walls of elastic and muscular arteries with oxygen and nutrients just as the coronary arteries provide for the walls of the heart (see Chapter 11 I B 1).
Which one of the following possesses a distinct internal elastic lamina? (A) Capillary (B) Metarteriole (C) Arteriole (D) Muscular artery (E) Vein
D. The muscular artery possesses a distinct internal elastic lamina. Elastic arteries possess an incomplete internal elastic lamina, whereas capillaries, arterioles, metarterioles, and veins do not possess an internal elastic lamina (see Table 1 1 . 1 and Chapter 1 1 I D).
Ischemic heart disease is the usual sequel to: (A) arteriosclerosis (B) abdominal aortic aneurysm. (C) rheumatic fever. (D) varicose veins. (E) atherosclerosis.
E. Ischemic heart disease is usually caused by coronary atherosclerosis, resulting in decreased blood flow to the myocardium. It may develop into angina pectoris, myocardial infarction, chronic ischemic cardiopathy, or sudden cardiac death. On the other hand, arteriosclerosis (hardening ofthe arteries) usually attacks renal arteries and is related to hypertension and diabetes mellitus (see Chapter 1 1 I B Clinical Considerations).
