Transport in humans
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Which route correctly takes blood from the aorta through a kidney and back towards the heart?
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Aorta -> renal artery -> kidney -> renal vein -> vena cava
Arterial blood reaches the kidney, and venous blood returns towards the heart.
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Which feature-function pair best explains a capillary?
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A one-cell-thick wall gives substances a short diffusion distance.
This supports rapid exchange between blood and the surrounding tissue fluid.
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Vessel X has a thick muscular wall and a narrow lumen. Vessel Y has a thin wall, a wide lumen and valves. Vessel Z has a wall one cell thick. Which identifies them?
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X artery, Y vein, Z capillary
Arteries have thick walls for high pressure, veins have valves and wide lumens, capillaries are one cell thick.
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A hormone and urea are travelling in blood. Which component mainly transports both?
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Plasma
Plasma transports hormones, urea and many other dissolved substances as well as the blood cells.
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Why can the immune system damage a transplanted organ?
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Its cells may carry antigens recognised as foreign by the recipient.
Immune recognition of different antigens can lead to tissue rejection.
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Which valve prevents backflow from the left ventricle into the left atrium?
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The bicuspid (mitral) valve
It closes when pressure in the left ventricle rises above pressure in the left atrium.
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During ventricular ejection, which valve arrangement allows one-way flow?
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Atrioventricular valves closed; semilunar valves open
Blood leaves for the arteries while backward flow into the atria is blocked.
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One cardiac cycle lasts 0.75 s. What is the heart rate?
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80 beats per minute
Heart rate = 60 / time for one cycle = 60 / 0.75 = 80 beats per minute.
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What is the most direct effect of a blocked coronary artery on the muscle it supplies?
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Less oxygen arrives, reducing aerobic energy release.
The muscle needs a continuing blood supply for respiration and contraction.
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A coronary artery is partly blocked by fatty deposits. Why can this cause chest pain during exercise?
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Heart muscle gets too little oxygen for the aerobic respiration it needs
Less blood reaches the heart muscle, so it cannot release enough energy aerobically when working hard.
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