Anatomy and Physiology Answer Key

B evidence when the heart is removed from its nervous

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Unformatted text preview: s in the vena cavae and atrium (venous return). The accelerator centre responds by sympathetic stimulation of the heart (via the cardiac nerve and release of norepinephrine) bringing about increased rate and force of heart contraction. Tricuspid 6. (a) Increased arterial flow (in aorta and carotid arteries). (b) Stretch receptors in carotid sinus and aorta detect an increase in arterial flow and send afferent impulses to the inhibitory centre in the medulla. The inhibitory centre mediates a decrease in heart rate via the vagus nerve (the carotid and aortic reflexes). There is a subsequent decrease in cardiac output and arterial blood pressure. 7. (a) and (b) any of the following in any order: – Aortic pressure receptors (baroreceptors) in the wall of the aortic arch respond to increased arterial blood flow in the aorta. – Carotid baroreceptors in the carotid sinus respond to increased arterial flow in the carotid artery. – Baroreceptors in the vena cava and the right atrium respond to increased venous return (mediates an increase in heart rate - the Bainbridge reflex). 8. (a) Individuals have different tolerances to the same level of a substance (also depends on their previous intakes of other substances such as coffee). Different body mass will affect the response also. (b) Controls should drink an energy drink that does not contain guarana. Bicuspid Semi-lunar valve Semi-lunar valve Right ventricle Left ventricle Valves prevent the blood from flowing the wrong way through the heart and help regulate filling of the chambers. 3. (a) The heart has its own coronary blood supply to meet the high oxygen demands of the heart tissue. (b) There must be a system within the heart muscle itself to return deoxygenated blood and waste products of metabolism back to the right atrium. 4. If blood flow to a particular part of the heart is restricted or blocked (because of blocked blood vessel), the part of the heart muscle supplied by that vessel will die, leading to a heart attack or infarction. 5. A: arterioles C: arterioles 6. (a) The pulmonary circuit mus...
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This document was uploaded on 01/28/2014.

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