In a cardiac cycle of 0.8 s, approximately how long is ventricular systole?
Correct answer B. 0.3 s
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MDCAT Biology MCQs
Page 17 of MDCAT Biology multiple-choice questions with answers. Tap an option to check yourself.
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During which phase of the cardiac cycle are both atria and ventricles relaxed while blood flows passively into the heart?
Correct answer B. Joint (complete) diastole
The second heart sound ‘dub’ is produced by ____.
Correct answer C. closure of the semilunar valves
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During ventricular systole, the semilunar valves open when ____.
Correct answer D. ventricular pressure exceeds the pressure in the aorta and pulmonary trunk
A person has a stroke volume of 70 mL and a heart rate of 72 beats per minute. What is the cardiac output?
Correct answer D. 5.04 L/min
A person’s cardiac output is 5.6 L/min and heart rate is 80 beats per minute. What is the stroke volume?
Correct answer D. 70 mL
Which wave of a normal electrocardiogram (ECG) represents depolarisation of the ventricles?
Correct answer A. QRS complex
The middle layer (tunica media) of an artery is thick mainly because it contains ____.
Correct answer C. smooth muscle and elastic fibres
Which feature is found in medium-sized veins of the limbs but NOT in arteries?
Correct answer D. Semilunar valves preventing backflow
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The walls of capillaries consist of ____.
Correct answer D. a single layer of endothelial cells
Blood flows most slowly through capillaries because ____.
Correct answer B. their total cross-sectional area is the largest of all vessels
Which blood vessels are mainly responsible for controlling peripheral resistance and the distribution of blood to organs?
Correct answer B. Arterioles
At which point in the systemic circulation is blood pressure lowest?
Correct answer D. Venae cavae near the right atrium
Tissue fluid is formed at the arterial end of a capillary mainly because ____.
Correct answer C. hydrostatic (blood) pressure exceeds the osmotic pull of plasma proteins
A normal resting blood pressure of a healthy young adult is about ____.
Correct answer C. 120/80 mmHg
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Smooth muscle fibres are best described as ____.
Correct answer C. spindle-shaped, uninucleate and non-striated
Skeletal muscle fibres are multinucleate because ____.
Correct answer B. each fibre forms by fusion of many embryonic myoblasts
The cell membrane of a skeletal muscle fibre is called the ____.
Correct answer C. sarcolemma
What is the role of the transverse (T) tubules in a skeletal muscle fibre?
Correct answer D. They carry action potentials from the sarcolemma deep into the fibre
The dark A band of a sarcomere corresponds to ____.
Correct answer B. the full length of the thick myosin filaments