Solns problem set#7

Solns problem set#7 - BIPN 108 Physiology of Exercise-Solutions to Problem Set#7 Page 1 1 i Endurance training increases the stroke volume of the

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BIPN 108, Physiology of Exercise--Solutions to Problem Set #7 Page 1 1. i. Endurance training increases the stroke volume of the heart even at rest. Cardiovascular regulatory mechanisms regulate blood pressure and cardiac output. A resting cardiac output of an endurance-trained athlete is no higher than the resting cardiac output of a sedentary person. The larger resting stroke volume requires fewer beats per minute to produce that resting cardiac output. ii. Endurance training reduces the level of norepinephrine and epinephrine in the blood, which will reduce the endogenous frequency of depolarizations in the sino-atrial node of the heart. iii. Endurance training boosts parasympathetic output onto the heart, which reduces the endogenous frequency of depolariazations in the sino-atrial node of the heart. 2. Any form of training drives the heart more than at rest (principally from signals that originate in the brain). Like any muscle, when heart muscle works harder the fibers synthesize more actin and myosin molecules and organize them into more myofibrils within the existing fibers. In endurance training, the average blood pressure rises only modestly or even not at all, so with each beat the heart is working against about the same pressure as at rest. However, in resistance training, the skeletal muscle fibers are driven to contract maximally, which causes individual fibers to increase in diameter and put pressure on the arteries running among the fibers. The net result is a sharp increase in peripheral resistance to flow in the arteries, which increases the average blood pressure. As a result, in this kind of training, the heart must work against this increased pressure, which causes the cardiac fibers to
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This note was uploaded on 04/19/2008 for the course BIPN 108 taught by Professor French during the Winter '08 term at UCSD.

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Solns problem set#7 - BIPN 108 Physiology of Exercise-Solutions to Problem Set#7 Page 1 1 i Endurance training increases the stroke volume of the

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