Chapter questions

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Chapter questions

Chapter 3

1 The maximum heart rate that could in theory be achieved by an obese 20-year-old individual is:

A 220 beats/min

B 200 beats/min

C 190 beats/min

D 180 beats/min

E 170 beats/min

2 During exercise, ventricular filling increases. Factors that contribute to this include:

A Increased intrathoracic pressure

B Increased ventricular contractility

C Increased heart rate

D Increased atrial contractility

E All of the above

3 During moderate exercise, cardiac output rises due to increases in both heart rate and stroke volume, but stroke volume peaks at a workload that is significantly below maximum work capacity and further increase of cardiac output is due solely to heart rate elevation. Factors that limit the rise in stroke volume include all of the following EXCEPT:

A Myocardial calcium channel cycle time

B Pericardial stiffness

C Limited catecholamine secretion

D Ventricular stiffness

E Ventricular afterload

4 The second heart sound:

A Marks the end of ventricular contraction

B Denotes the end of systolic ejection

C Coincides with the end of the T wave

D Is prolonged in the presence of A/V valvular incompetence

E All of the above

5 CO₂ production is measured in an exercising subject, in order to calculate cardiac output by the Fick principle. The values obtained are:

Cardiac output is, therefore:

Chapter 4

1 The elevation of systolic blood pressure caused by sympathetic nervous system activation involves:

A Increased cardiac contractility

B Shortened QRS duration

C Reduced aortic compliance

D Reduced venous capacity

E All of the above

2 A subject has a resting heart rate of 66 beats/min and a blood pressure of 114/60 mmHg. Her mean arterial blood pressure is, therefore:

3 Routine measurement of blood pressure by auscultation involves detection of Korotkow sounds during inflation of an occlusive cuff around the arm. These sounds are caused by:

A Turbulent flow in the segment of artery just downstream of the cuff

B Turbulent flow in the segment of artery compressed by the cuff

C Collision of blood with the upstream margin of the cuff

D Turbulent flow in the segment of artery just upstream of the cuff

E Intermittency of blood flow due to the occlusive pressure being greater than DBP

4 Arterial pulse pressure:

A Is increased if peripheral resistance falls while stroke volume and heart rate remain constant

B Is reduced if peripheral resistance falls while stroke volume and heart rate remain constant

C Is unaffected if peripheral resistance falls while stroke volume and heart rate remain constant

D Is greater in the aorta than in the brachial artery

E Is directly proportional to heart rate

5 A subject undertook steady treadmill exercise at 70% maximum work capacity. His BP was 160/64 mmHg and his cardiac output as measured by CO₂ rebreathing was 16 l/min. His total peripheral resistance was therefore:

Chapter 5

1 Laplace’s law dictates that, in blood vessels:

A Wall tension is proportional to the ratio of wall thickness: luminal diameter

B Small vessels are more likely to rupture with increased wall tension than are large ones

C Veins are more likely to rupture with increased wall tension than are arteries

D Critical closing pressure is higher in microcirculatory beds with high sympathetic vasomotor tone

E The presence of elastin in the aortic wall reduces the rise in wall tension associated with BP elevation

In the above set of curves describing the relationship between pressure gradient and blood flow, which curve represents:

2 Flow through a rigid tube

3 Flow through a relaxed vessel the wall of which contains large amounts of elastin

4 Flow through a relaxed vessel the wall of which contains little elastin

5 Flow through a vessel the wall of which contains large amounts of elastin and in which the smooth muscle is maximally contracted by sympathetic nerve activation

6 Blood viscosity:

A Is higher in arterial than in arteriolar blood

B Rises with haematocrit

C Is lowest in capillaries

D Falls as flow velocity increases

E All of the above

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