Chapter questions

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Chapter questions

Chapter 2

imageWhich of the labelled time intervals on the ECG record shown above:

1 Has a lower normal limit of 120 ms?
2 Is 500 ms in a person with a heart rate of 120 beats/min?
3 Marks the duration of the endocardial ventricular refractory period?
4 Is shortened by increasing the velocity of action potential conduction through the myocardial syncytium?
5 Indicates the time available for ventricular filling?
6 Is never longer than 80 ms in a normal heart?

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:

image

image

image

Cardiac output is, therefore:

A 4 l/min
B 6 l/min
C 10 l/min
D 15 l/min
E 24 l/min

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:

A 78 mmHg
B 82 mmHg
C 87 mmHg
D 92 mmHg
E 96 mmHg

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:

A 0.14 PRU
B 0.16 PRU
C 4 PRU
D 6 PRU
E 7 PRU

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

imageIn 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

Chapter 6

1 Vasomotion:

A Occurs only in large arteries
B Depends on variations in sympathetic vasomotor tone
C Depends on variations in critical closing pressure
D Occurs more slowly when tissue metabolic rate rises
E Occurs typically with a cycle time of 20–30 ms

2 Functional hyperaemia in skeletal muscle during exercise:

A Is associated with a rise in muscle blood flow of up to 100-fold
B Commences within a few seconds of the initiation of muscle activity
C Is due primarily to endothelial factors
D Involves muscle-derived PGs especially in glycolytic motor units
E Involves α-adrenoceptor activation by circulating catecholamines

A. kallidin, B. NO, C. potassium ion, D. adrenaline, E. lactate. Which of the dilator mediators listed:

3 Contributes to functional hyperaemia in skin?
4 Contributes to functional hyperaemia by activating guanylate cyclase?
5 Increases capillary permeability as well as causing vasodilation?
6 Is released when blood flow velocity increases?

Chapter 7

1 The baroreflex response to reduced venous return:

A Affects peripheral resistance mainly in renal and cutaneous circulations
B Is more pronounced when arterial compliance is low
C Results from excitatory inputs from the baroreceptor afferent pathway onto the hindbrain neurons that control sympathetic drive
D Has minimal effects on skeletal muscle vascular resistance
E Includes stimulation of vasopressin release

2 During exercise there is a generalized increase in sympathetic vasoconstrictor discharge. However, glomerular filtration is maintained because:

A Renal sympathetic innervation is only to vessels of the renal medulla
B Renal sympathetic innervation affects the large arteries but not the microcirculation
C Sympathetic activation preferentially constricts the afferent renal arterioles
D Sympathetic activation preferentially constricts the efferent renal arterioles
E Autoregulation prevents sympathetic activation from reducing renal blood flow

3 During exercise, mean BP is maintained at a higher value than at rest because:

A The exercise-related sympathetic excitation is so powerful that it overrides the baroreflex
B The gain of the baroreflex is reduced
C The operating point of the baroreflex is shifted
D The baroreflex is not effective when stroke volume is large
E The BP increase that occurs is a normal baroreflex response to increased venous return

4 The rise in BP associated with exercise is:

A Greater with dynamic than with static exercise
B Greater with upper-body than with whole-body exercise
C In dynamic exercise, due mainly to muscle metaboreceptor activation
D More pronounced for DBP than for SBP
E Always proportional to the degree of tachycardia

5 During exercise, the increase in coronary blood flow:

A Is around fourfold if cardiac output increases fourfold
B Involves a change from intermittent to continuous capillary perfusion
C Is greater in right than in left ventricle
D Is due primarily to β-adrenoreceptor activation
E None of the above

6 The elevation of BP during static exercise:

A Is due primarily to limb mechanoreceptor activation
B Is greatest at maximal workload
C Is greater in magnitude for DBP than for SBP
D Is minimal unless a large muscle mass is involved
E None of the above

Chapter 8

1 The pulmonary ventilation:perfusion ratio:

A Is greater than 1.0 throughout the lung, in a supine resting subject
B Is less than 1.0 throughout the lung, in a supine resting subject
C Is greater than 1.0 in the upper thorax, in a standing resting subject
D Is less than 1.0 in the upper thorax, in a standing resting subject
E Is 1.0 throughout the lung, in a standing resting subject

2 The pulmonary pressure gradient is only around one-seventh of that in the systemic circulation. As a result:

A Pulmonary capillary hydrostatic pressure is similar to intra-alveolar pressure
B Cardiac workload is greater in right heart than in the left heart
C Cardiac workload rises more in the right than in the left heart when cardiac output increases
D Pulmonary wedge pressure can be used as a beat-to-beat index of left ventricular pressure
E Right coronary perfusion is continuous rather than intermittent

3 Efficient blood oxygenation during heavy exercise involves:

A Mechanical expansion of non-ventilated areas of lung
B Dilation of pulmonary arterioles by withdrawal of hypoxia receptor stimulation
C Elevated systolic pulmonary arterial pressure
D All of the above
E None of the above

4 Full O2 saturation of blood can be achieved during moderate exercise without any alterations in ventilation:perfusion matching BECAUSE:

A At rest, not all the available haemoglobin molecules are fully saturated
B At rest, the O2 content of the pulmonary capillary plasma is higher than is needed for haemoglobin saturation
C At rest, O2 concentrations in plasma and alveolar air equilibrate before the plasma has traversed the pulmonary capillary
D Exercise shifts the haemoglobin dissociation curve to the right
E Exercise shifts the haemoglobin dissociation curve to the left

5 In the fetal circulation, the entire systemic venous return bypasses the pulmonary circulation BECAUSE:

A The partition between left and right ventricles is not yet developed
B The lungs are filled with fluid
C Local PG secretion causes pulmonary vasoconstriction
D Low fetal blood oxygenation causes pulmonary vasoconstriction
E The atrioventricular valves are not yet developed

Chapter 9

1 Fluid loss due to sweating during exercise:

A Is associated with loss of around 2.5 g sodium chloride/l sweat in a non-heat acclimatized subject
B May be up to 5l fluid/h during heavy exercise in a non-heat acclimatized subject
C Is greater under conditions of low environmental humidity
D Is more pronounced in children than in adults
E Is more pronounced in elderly than in young adults

2 Fluid replacement during exercise is facilitated by:

A Ensuring that the fluid is as cold as possible
B Ingesting large volumes infrequently
C Using a hypertonic fluid
D Using an isotonic fluid
E Adding small amounts of glucose to the fluid

3 During continuous dynamic exercise, work capacity falls BECAUSE:

A Increased skin blood flow reduces muscle perfusion
B Circulating blood volume falls
C Blood viscosity rises
D Cardiac filling time decreases
E All of the above

4 Cardiovascular function during swimming differs from that during running in that:

A Sweat is removed from the skin more efficiently
B Greater intrathoracic suction increases venous return
C The external pressure reduces venous return
D The reduced gravitational field increases venous return
E Muscle perfusion is a smaller proportion of total cardiac output

5 In adults, the capacity for exercise decreases with age BECAUSE:

A Increased cardiac compliance reduces cardiac ejection fraction
B Increased resting heart rate reduces heart rate reserve
C Reduced heart rate reserve decreases cardiac filling time
D Increased aortic compliance reduces the pressor response
E Both B and C.

Chapter 10

1 The Valsalva manoeuvre can result in fainting in athletes undertaking heavy resistive exercise. Factors involved in this loss of consciousness include:

A Cerebral vasoconstriction due to hypocapnia
B Cerebral vasoconstriction due to adrenomedullary stimulation
C Plasma volume depletion
D All of the above
E Both A and B above

2 The recreational drug ecstasy has all of the following effects EXCEPT:

A Resetting the hypothalamic thermostat
B Reducing skin blood flow
C Uncoupling mitochondrial respiration from ATP production
D Decreasing thyroid hormone secretion
E Stimulating central sympathetic drive

3 Individuals with defects in the RYR1 gene may be at danger during exercise. This is because:

A The RYR1 gene controls calcium movement across the muscle cell membrane
B The RYR1 gene controls calcium release from the sarcoplasmic reticulum
C The RYR1 gene controls calcium movement into vascular smooth muscle
D These individuals cannot produce enough muscle contraction to sustain exercise
E These individuals cannot produce enough muscle vasodilation to sustain exercise

4 Exertional hyperthermia:

A Is most likely in humid environments
B Cannot occur so long as plasma volume is not depleted
C Is most effectively treated by immersion in chilled water
D Results in cessation of exercise before the core temperature becomes dangerously high
E All of the above

5 Fluid depletion:

A Results in hypotension if blood volume falls by more than 5%
B Affects muscle perfusion before it affects other regional beds
C Affects renal and intestinal function because of the presence of counter-current loops
D Is the basis of the syndrome termed ‘heat stroke’
E All of the above

Chapter 11

A Heart rate reserve 150 beats/min, cardiac reserve 18 l/min, maximum sweat rate 1.2 l/h, sweat sodium content 45 mmol
B Heart rate reserve 120 beats/min, cardiac reserve 18 l/min, maximum sweat rate 1.2 l/h, sweat sodium content 45 mmol
C Heart rate reserve 130 beats/min, cardiac reserve 19 l/min, maximum sweat rate 1.5 l/h, sweat sodium content 10 mmol
D Heart rate reserve 150 beats/min, cardiac reserve 24 l/min, maximum sweat rate 1.5 l/h, sweat sodium content 10 mmol
E Heart rate reserve 120 beats/min, cardiac reserve 24 l/min, maximum sweat rate 1.5 l/h, sweat sodium content 10 mmol
F Heart rate reserve 150 beats/min, cardiac reserve 24 l/min, maximum sweat rate 1.5 l/h, sweat sodium content 10 mmol
G Heart rate reserve 150 beats/min, cardiac reserve 24 l/min, maximum sweat rate 1.5 l/h, sweat sodium content 45 mmol

In a healthy, 30-year-old subject (resting HR 72 beats/min, resting cardiac output 5.4 l/min), which of the above sets of values best represent the situation:
1 In the sedentary state
2 After dynamic exercise training for 3 weeks
3 After dynamic training for 6 months
4 The earliest detectable cardiovascular adaptation to training is:

A A fall in resting heart rate
B A rise in haematocrit
C A rise in plasma volume
D A decrease in resting stroke volume
E An increase in resting stroke volume

5 Eccentric cardiac hypertrophy:

A Involves increases in both ventricular muscle mass and ventricular chamber volume
B Occurs in response to increased afterload
C During training, occurs in left heart before it occurs in right heart
D Is maximal after around 3 months’ training
E Is more likely to be associated with cardiac arrhythmias than is concentric hypertrophy

6 Chronic dynamic exercise is thought to reduce the risk of atherogenesis. Probable mechanisms involved include:

A Reduced microcirculatory shear stress
B Slower endothelial cell turnover
C Lower peripheral resistance
D Increased sympathetic drive
E All of the above

Chapter 12

A PaO2 55 mmHg, PaCO2 30 mmHg, arterial pH 7.40
B PaO2 55 mmHg, PaCO2 30 mmHg, arterial pH 7.45
C PaO2 55 mmHg, PaCO2 35 mmHg, arterial pH 7.65
D PaO2 100 mmHg, PaCO2 40 mmHg, arterial pH 7.40
E PaO2 100 mmHg, PaCO2 40 mmHg, arterial pH 7.35
F PaO2 90 mmHg, PaCO2 50 mmHg, arterial pH 7.35
G PaO2 100 mmHg, PaCO2 50 mmHg, arterial pH 7.35

Which of the above blood gas profiles is most likely to have come from:
1 A resident at sea level, at rest
2 A resident at sea level, at the end of a 5000 m race
3 A resident at sea level, 3 h after ascent to an altitude of 3000 m
4 An individual who has been resident at 3000 m for several days
5 Exercise performance is reduced by altitude more in trained athletes than in sedentary individuals BECAUSE:

A Training shifts the haemoglobin saturation curve to the right
B Training shifts the haemoglobin saturation curve to the left
C The greater cardiac output achieved in athletes reduces pulmonary oxygen uptake
D The increased haematocrit in athletes increases their cardiac workload
E Absolute work capacity is reduced by hypoxia

6 A young man collapses during a winter hill walk. He is not shivering and, although he is conscious, he seems confused. This picture is characteristic of deep body temperatures in the range:

A 35–36° C
B 34–35° C
C 32–34° C
D 30–32° C
E 28–30° C

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