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Question 01
Regarding the conduction system of the heart:
a) Between action potentials, the cells of the sino-atrial node have a steady resting potential. b) The cardiac action potential is conducted through the atria via Purkinje fibers. c) The Purkinje fibers are specialized cardiac myocytes linked by gap junctions. d) The spread of cardiac excitation speeds up at the atrio-ventricular node .Question 02
Regarding the ECG:
a) The P wave of the ECG reflects atrial contraction. b) The P-Q interval is normally about 0.1s. c) The QRS complex reflects the start of ventricular contraction. d) The peak amplitude of the ECG recorded by the limb leads is about 10 mV .Question 03
During the cardiac cycle of a normal healthy young adult:
a) During ventricular diastole the pressure in the left ventricle is close to 80 mm Hg (10.6 kPa). b) During ventricular systole, the pressure in the left ventricle reaches a maximum of about 25 mm Hg (3.3 kPa). c) During the initial stage of ventricular contraction the volume of the ventricle does not change. d) During ventricular systole, all the blood in the ventricles is ejected. Question 04
Concerning the normal heart sounds:
a) The first heart sound corresponds with the closure of the mitral and tricuspid valves. b) The first heart sound occurs just before the R wave of the ECG. c) The first heart sound is split into two components during inspiration. d) The second heart sound occurs during the T-wave .Question 05
The cardiac output:
a) Is increased by aldosterone released from the adrenal medulla. b) Is increased by stimulation of the vagus nerve. c) Can be measured by dividing the oxygen consumption by the difference in PO2 of the venous and arterial blood. d) Is largely determined by the end-diastolic volume. Question 06
The arterial blood pressure:
a) Is 120/80 mm Hg (16/10.6 kPa). b) Depends solely on the cardiac output. c) Is the arithmetic average of the systolic and diastolic pressures. d) Is due to the vascular resistance of the capillaries .Question 07
Concerning the control of the vasculature:
a) Autoregulation refers to the nervous control of the blood vessels. b) Reactive hyperemia is due to vasodilatation caused by accumulation of metabolites during a period of exercise. c) Parasympathetic vasodilator fibers innervate the blood vessels of the exocrine glands of the gastro-intestinal tract. d) The diameter of the arterioles is entirely regulated by the sympathetic nervous system .Question 08
Concerning the microcirculation:
a) The exchange of solutes between the capillaries and tissues occurs mainly by bulk flow. b) The capillaries provide a significant source of vascular resistance. c) All of the fluid that passes from the capillaries to the tissues is returned to the blood via the lymphatic circulation. d) The plasma proteins play an important role in tissue fluid exchange .Question 09
Concerning the nervous regulation of the circulation:
a) The baroreceptors are mainly responsible for the long-term regulation of systemic blood pressure. b) If the arterial pressure suddenly falls the baroreceptor reflex increases the heart rate. c) The baroreceptors are found in the aortic and carotid bodies. d) The coronary blood flow is regulated by the cardiac volume receptors.
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Question 1
Regarding the conduction system of the heart:
Your Answer:
c) The Purkinje fibers are specialized cardiac myocytes linked by gap junctions.
Feedback:
The cells of the SA node have no steady resting potential but show a slow change in potential known as the pacemaker potential. The conduction of the cardiac impulse through the atria occurs via normal atrial myocytes. In the ventricles, the specialized conducting cells are the bundle cells and the Purkinje fibers, which transmit their action potentials to the ventricular myocytes via gap junctions. The speed of conduction is slowed as the cardiac action potential passes through the AV node.
Page reference: 266
Question 2
Regarding the ECG:
Your Answer:
b) The P-Q interval is normally about 0.1s.
Feedback:
The P wave reflects atrial depolarization and precedes atrial contraction. Likewise, the QRS complex reflects the start of ventricular depolarization. The peak amplitude of the ECG recorded by the limb leads is about 1 mV.
Page reference: 270
Question 3
During the cardiac cycle of a normal healthy young adult:
Your Answer:
c) During the initial stage of ventricular contraction the volume of the ventricle does not change.
Feedback:
During the cardiac cycle the pressure in the left ventricle is around zero during diastole and 120 mmHg (16Kpa) at the peak of systol
Page reference: 273-275
Question 4
Concerning the normal heart sounds:
Your Answer:
a) The first heart sound corresponds with the closure of the mitral and tricuspid valves.
Feedback:
Since the first heart sound is caused by closure of the atrio-ventricular valves, it must occur after the onset of ventricular contraction, which follows the R wave. The second heart sound is caused by the closure of the aortic and pulmonary valves. It consists of two components designated A2 and P2, which occur at slightly different times during the respiratory cycle. The second heart sound occurs at the end of systole when the ventricles have repolarized and therefore occurs just after the T-wave.
Page reference: 276
Question 5
The cardiac output:
Your Answer:
d) Is largely determined by the end-diastolic volume
Feedback:
Cardiac output is increased by circulating epinephrine (adrenaline), not by aldosterone, which is secreted by the adrenal cortex. Cardiac output is decreased by vagal stimulation. It can be measured by dividing the oxygen consumption of the body by the difference in oxygen content between the mixed venous and the arterial blood. (This is the Fick principle).
Page reference: 277-283
Question 6
The arterial blood pressure:
Your Answer:
a) Is 120/80 mm Hg (16/10.6 kPa).
Feedback:
The arterial blood pressure of a young healthy adult is approximately 120/80 mmHg. It depends on the cardiac output and the total peripheral resistance. The mean arterial pressure is equal to the diastolic pressure plus one third of the pulse pressure. The peripheral resistance is determined by the degree of constriction of the arterioles (arteriolar tone).
Page reference: 285-287
Question 7
Concerning the control of the vasculature:
Your Answer:
c) Parasympathetic vasodilator fibers innervate the blood vessels of the exocrine glands of the gastro-intestinal tract.
Feedback:
Autoregulation occurs in denervated blood vessels and is an intrinsic property. Reactive hyperemia is due to vasodilatation caused by accumulation of metabolites during a period of occluded blood flow. The increased blood flow during exercise is active hyperemia. The arterioles are under nervous, hormonal and local control.
Page reference: 289-293
Question 8
Concerning the microcirculation:
Your Answer:
d) The plasma proteins play an important role in tissue fluid exchange.
Feedback:
Solute exchange between the capillaries and tissues occurs mainly by diffusion. The arterioles are the main source of vascular resistance. A fraction of the fluid that leaves the capillaries at the arteriolar end is reabsorbed by the capillaries during constriction of the arterioles. The fraction that is not absorbed is returned to the circulation via the lymph.
Page reference: 293-298
Question 9
Concerning the nervous regulation of the circulation:
Your Answer:
b) If the arterial pressure suddenly falls the baroreceptor reflex increases the heart rate.
Feedback:
The baroreceptors are responsible for the short-term regulation of the arterial blood pressure. The baroreceptors are located in the carotid sinus and aortic arch. The coronary blood flow is mainly regulated by metabolic hyperemia.
Page reference: 299-302
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