Cardiovascular Physiology Quiz

Concerning transport by the cardiovascular system, a. the transport of glucose by the circulation is convective rather than diffusive. b. diffusion depends on transport up a concentration gradient. c. the time taken for O2 to diffuse a certain distance is directly proportional to the distance. d. O2 is carried from capillary blood to the tissue cells mainly by fluid filtration. e. if coronary perfusion were halted, O2 would take about 15 hours to diffuse from the cavity of the left ventricle to the subepicardial muscle fibres.

• True

• False

• True

• False

• False

Regarding the distribution of cardiac output (CO) to the tissues of a resting human, a. about 20% goes to skeletal muscle, which accounts for 20% of resting O2 consumption. b. about 20% goes to the kidneys, which account for 6% of resting O2 consumption. c. about 10% goes to the myocardium, which accounts for 10% of resting O2 consumption. d. the proportion of the CO going to a given organ is regulated mainly by the conduit arteries feeding the organ. e. about 50% goes to the lungs, due to their low vascular resistance.

• True

• True

• True

• True

• False

Regarding the flow of blood, a. flow is proportional to the pressure difference between the inlet and outlet of the blood vessel. b. Darcy’s law states that flow equals pressure times resistance. c. the flow per unit pressure drop along a vessel is called the hydraulic conductance of the vessel. d. the units for hydraulic resistance are mmHg per unit flow or equivalent. e. the flow resistance of the pulmonary circulation is about two-thirds that of the systemic circulation.

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• True

• True

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• True

As blood flows around the systemic circulation, a. its mean pressure falls markedly from the aorta to small, named arteries, such as the radial artery. b. the systolic pressure is higher in the brachial artery than the aorta. c. the biggest fall in pressure occurs in the resistance arteries. d. the greatest net, cross-sectional vascular area is encountered in the capillaries. e. its velocity decreases in microvessels, yet the total flow does not. f. its pressure falls to 30 mmHg in the antecubital vein at heart level.

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The conclusion that terminal arteries and arterioles offer more resistance to blood flow than other vessels stems from the observation that a. they have the thickest walls, relative to lumen width. b. they have a rich sympathetic vasomotor innervation. c. they have the smallest internal radius of all blood vessels. d. they have the biggest pressure drop across them. e. they are less numerous than venules.

• True

• True

• True

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Blood vessels classified as a. elastic vessels expand to receive the stroke volume of the heart. b. conduit vessels conduct venous blood back to the heart. c. resistance vessels can actively regulate the blood flow through a tissue. d. exchange vessels include some venules as well as capillaries. e. capacitance vessels have the capacity to alter blood pressure directly.

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• True

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• False

The wall of a blood vessel is lined internally by cells that secretes anti-thrombotic agents.

The proximal aorta gives off arteries to the brain; the abdominal aorta gives off arteries to the intestine; and the distal aorta gives off arteries to the leg; but the liver is supplied chiefly by venous blood from the intestine. Therefore, the blood supply to the brain and intestine are in parallel.

Regarding the various systemic blood vessels, enter the code from the list below to answer questions (i) to (vii). A code can be used more than once, or not at all. (i) This vessel has the largest radius.

• proximal aorta

• conduit arteries

• capillaries

• venules

• arterioles

During cardiac development in the fetus, the ductus arteriosus shunts blood from the aorta into pulmonary trunk.