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Question 1
Correct
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On reviewing the ECG of a patient with a history of intermittent palpitations, you observe prolonged QT interval.
Which of these can cause prolongation of the QT interval on the ECG?
Your Answer: Erythromycin
Explanation:Syncope and sudden death due to ventricular tachycardia, particularly Torsades-des-pointes is seen in prolongation of the QT interval.
The causes of a prolonged QT interval include:
Erythromycin
Amiodarone
Quinidine
Methadone
Procainamide
Sotalol
Terfenadine
Tricyclic antidepressants
Jervell-Lange-Nielsen syndrome (autosomal dominant)
Romano Ward syndrome (autosomal recessive)
Hypothyroidism
Hypocalcaemia
Hypokalaemia
Hypomagnesaemia
Hypothermia
Rheumatic carditis
Mitral valve prolapse
Ischaemic heart disease -
This question is part of the following fields:
- Cardiovascular Physiology
- Physiology
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Question 2
Correct
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You evaluate a 80-year-old man who has a history of persistent heart failure and discover that he has generalised oedema.
Which of the following claims regarding capillary hydrostatic pressure (P c) is false?Your Answer: P c increases along the length of the capillary, from arteriole to venule
Explanation:The capillary hydrostatic pressure (Pc) is normally between 15 and 30 millimetres of mercury. Pc Decreases along the capillary’s length, mirroring the arteriolar and venule pressures proximally and distally.
Pc is determined by the ratio of arteriolar resistance (RA) to venular resistance (RV).When the RA/RV ratio is high, the pressure drop across the capillary is modest, and Pcis is close to venule pressure.
When the ratio of RA/RV is low, the pressure drop across the capillary is considerable, and Pcis is close to arteriolar pressure.
Pcis closer to the venule pressure and thus more responsive to changes in venous pressure than arteriolar pressure when RA/RV is high.
Pcis the major force behind fluid pushing out of the capillary bed and into the interstitium.
It is also the most variable of the forces affecting fluid transport at the capillary, partly because sympathetic-mediated arteriolar vasoconstriction varies. -
This question is part of the following fields:
- Cardiovascular Physiology
- Physiology
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Question 3
Incorrect
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A 30-year-old woman was involved in a road traffic accident and had a class I haemorrhage.
Which physiological parameter is consistent with a diagnosis of class I haemorrhage?
Your Answer: Pulse rate of 115 bpm
Correct Answer: Increased pulse pressure
Explanation:There are 4 classes of haemorrhage. Classification is based on clinical signs and physiological parameters.
In CLASS I:Blood loss (ml) is < or = 750
Blood loss(% blood volume) < or = 15%
Pulse rate (bpm) is <100
Respiratory rate is 14-20
Urine output (ml/hr) is >30
Pulse pressure is normal or increased
Systolic BP is normal
CNS/mental status patient is slightly anxiousIn CLASS II:
Blood loss (ml) is 750 – 1500
Blood loss(% blood volume) is 15 – 30%
Pulse rate (bpm) is 100 – 120
Respiratory rate is 20-30
Urine output (ml/hr) is 20-30
Pulse pressure is decreased
Systolic BP is normal
CNS/mental status patient is mildly anxiousIn CLASS III:
Blood loss (ml) is 1500 – 2000
Blood loss(% blood volume) is 30- 40%
Pulse rate (bpm) is 120 – 140
Respiratory rate is 30-40
Urine output (ml/hr) is 5-15
Pulse pressure is decreased
Systolic BP is decreased
CNS/mental status patient is anxious, confusedIn CLASS IV:
Blood loss (ml) is >2000
Blood loss(% blood volume) is >40%
Pulse rate (bpm) is >140
Respiratory rate is >40
Urine output (ml/hr) is negligible
Pulse pressure is decreased
Systolic BP is decreased
CNS/mental status patient is confused, lethargic -
This question is part of the following fields:
- Cardiovascular Physiology
- Physiology
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Question 4
Correct
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The cutaneous circulation is responsible for the skin's blood supply. Because the skin is not a highly metabolically active tissue with low energy requirements, its blood supply differs from that of other tissues. Instead of capillaries, some of the circulating blood volume in the skin passes through arteriovenous anastomoses (AVAs).
Which of the following statements regarding arteriovenous anastomoses is correct?
Your Answer: AVAs are innervated by sympathetic fibres originating from the hypothalamus
Explanation:Short vessels called arteriovenous anastomoses (AVAs) link tiny arteries and veins. They have a large lumen diameter. The strong and muscular walls allow AVAs to completely clog the vascular lumen, preventing blood flow from artery to vein (acting like a sphincter). When the AVAs open, they create a low-resistance connection between arteries and veins, allowing blood to flow into the limbs’ superficial venous plexuses. There is no diffusion of solutes or fluid into the interstitium due to their strong muscle walls.
AVAs are densely innervated by adrenergic fibres from the hypothalamic temperature-regulation centre. High sympathetic output occurs at normal core temperatures, inducing vasoconstriction of the AVAs and blood flow through the capillary networks and deep plexuses. When the temperature rises, sympathetic output decreases, producing AVA vasodilation and blood shunting from the artery to the superficial venous plexus. Heat is lost to the environment as hot blood rushes near to the skin’s surface.
AVAs are a specialized anatomical adaptation that can only be found in large quantities in the fingers, palms, soles, lips, and pinna of the ear. -
This question is part of the following fields:
- Cardiovascular Physiology
- Physiology
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Question 5
Incorrect
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Metabolic hyperaemia harmonizes local blood flow with local O2 demand. If there is an increase in metabolic rate, the production of vasoactive metabolites increases. These metabolites act locally on the surrounding arterioles, causes vasodilation and an increase blood supply.
Which of these metabolites is the most potent vasodilator in skeletal muscle?Your Answer: CO 2
Correct Answer: K +
Explanation:Hyperaemia is the process where the body adjusts blood flow to meet the metabolic needs of different tissues in health and disease. Vasoactive mediators that take part in this process include K+, adenosine, CO2, H+, phosphates and H2O2. Although the mechanism is not clear, all these mediators likely contribute to some extent at different points.
Specific organs are more sensitive to specific metabolites:
K+ and adenosine are the most potent vasodilators in skeletal musclesCO2 and K+ are the most potent vasodilators in cerebral circulation.
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This question is part of the following fields:
- Cardiovascular Physiology
- Physiology
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Question 6
Correct
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The term cardiac output refers to the amount of blood pumped by the heart in one minute. The rate in women is around 5 L/min, whereas in men is somewhat higher, around 5.5 L/min.
Which of the equations below best describes cardiac output?
Your Answer: Stroke volume x heart rate
Explanation:Cardiac output (CO) is calculated by multiplying stroke volume (SV) by heart rate (HR):
CO = HR x SVAs a result, both stroke volume and heart rate are exactly proportional to cardiac output. There will be an increase in cardiac output if the stroke volume or heart rate increases, and a reduction in cardiac output if the stroke volume or heart rate lowers.
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This question is part of the following fields:
- Cardiovascular Physiology
- Physiology
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Question 7
Correct
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You've been requested to give a discussion to a group of medical students about cardiovascular physiology. One of them inquires about cardiac output and asks if you can explain it.
Which of the following statements is correct?
Your Answer: An average resting cardiac output in a woman is 5 L/min
Explanation:The terminology cardiac output refers to the amount of blood pumped by the heart in one minute. Women’s rates are around 5 L/min, whereas men’s rates are somewhat higher, around 5.5 L/min.
Cardiac output (CO) is calculated by multiplying stroke volume (SV) by heart rate (HR):
CO = HR x SVAs a result, both stroke volume and heart rate are exactly proportional to cardiac output. There will be an increase in cardiac output if the stroke volume or heart rate increases, and a reduction in cardiac output if the stroke volume or heart rate lowers.
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This question is part of the following fields:
- Cardiovascular Physiology
- Physiology
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Question 8
Correct
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An 80-year-old patient with a history of chronic heart failure presents to you. Examination reveals widespread oedema.
Which statement about plasma oncotic pressure (π p ) is true?Your Answer: The influence of π p on fluid movement is negligible if the capillary reflection co-efficient is 0.1
Explanation:Plasma oncotic pressure (πp) is typically 25-30 mmHg.
70% of π p is generated by albumin so Hypoalbuminemia will decrease π p
The osmotic power of albumin is enhanced by the Gibbs-Donnan effect.
The influence of π p on fluid movement is negligible if the capillary reflection coefficient is 0.1. Another way of saying a vessel is highly permeable is saying the reflection coefficient is close to 0.
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This question is part of the following fields:
- Cardiovascular Physiology
- Physiology
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Question 9
Correct
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The ECG of a patient presenting with a history of intermittent palpitations has a prolonged QT interval.
Which of these can cause prolongation of the QT interval on the ECG?Your Answer: Hypomagnesaemia
Explanation:The causes of a prolonged QT interval include:
Hypomagnesaemia
Hypothermia
Hypokalaemia
Hypocalcaemia
Hypothyroidism
Jervell-Lange-Nielsen syndrome (autosomal dominant)
Romano Ward syndrome (autosomal recessive)
Ischaemic heart disease
Mitral valve prolapse
Rheumatic carditis
Erythromycin
Amiodarone
Quinidine
Tricyclic antidepressants
Terfenadine
Methadone
Procainamide
Sotalol -
This question is part of the following fields:
- Cardiovascular Physiology
- Physiology
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Question 10
Correct
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At rest, skeletal muscle accounts for between 15-20% of cardiac output and accounts for around 50% of body weight. This can increase to nearly 80% of cardiac output during exercise. Skeletal muscle circulation is highly controlled and has a number of specialized adaptations as a result of this high degree of disparity during exercise, in combination with the diversity in the size of skeletal muscle around the body.
What is the primary mechanism for boosting skeletal muscle blood flow during exercise?
Your Answer: Metabolic hyperaemia
Explanation:In skeletal muscle, blood flow is closely related to metabolic rate. Due to the contraction of precapillary sphincters, most capillaries are blocked off from the rest of the circulation at rest and are not perfused. This causes an increase in vascular tone and vessel constriction. As metabolic activity rises, this develops redundancy in the system, allowing it to cope with greater demand. During exercise, metabolic hyperaemia, which is induced by the release of K+, CO2, and adenosine, recruits capillaries. Sympathetic vasoconstriction in the active muscles is overridden by this. Simultaneously, blood flow in non-working muscles is restricted, preserving cardiac output. During exercise, muscle contractions pump blood through the venous system, raising the pressure differential between arterioles and venules and boosting blood flow via capillaries.
Capillary angiogenesis is evident when muscles are used repeatedly (e.g. endurance training). It is a long-term effect, not a quick fix for increased blood flow.
The local partial pressure of alveolar oxygen is the primary intrinsic control of pulmonary blood flow (pAO2). Low pAO2 promotes arteriole vasoconstriction and vice versa. The hypoxic pulmonary vasoconstriction (HPV) reflex allows blood flow to be diverted away from poorly ventilated alveoli and towards well-ventilated alveoli in order to maximize gaseous exchange.
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This question is part of the following fields:
- Cardiovascular Physiology
- Physiology
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SESSION STATS - PERFORMANCE PER SPECIALTY
