Following change is noted during exercise.
Correct Answer: Body temperature increases
Description: Body temperature increases 00767837] Heat is produced whenever muscles contract. This is due to 2 reasons The maximal efficiency for conversion of nutrient energy into muscle work, even under best conditions, is only 20 to 25 per cent. Almost all the energy used to contract the muscle is conveed into heat d/t overcoming viscous resistance to the movement of the muscle and joints. overcoming the friction of blood flowing through the blood vessels. other similar effects. Changes in Muscle blood flow during exercise: The blood flow of resting skeletal muscle is low (2-4 ml./100 g/inin). The muscle blood flow can increase a maximum of about 25 fold during the most strenuous exercise. Almost one half of this increase in flow is due to intramuscular vasodilatation caused by the direct effects of increased muscle metabolism. The remaining increase results from multiple factors, the most impoant of which is probably the moderate increase in aerial blood pressure that occurs in exercise, usually about a 30 per cent increase. The increase in pressure not only forces more blood through the blood vessels but also stretches the walls of the aerioles and fuher reduces the vascular resistance. The local mechanisms maintaining a high blood flow in exercising muscle include a fall in tissue P02, a rise in tissue PCO2, and accumulation of K+, and other vasodilator metabolites. The rise in temperature fuher dilates the vessels. The increase in blood flow is instantaneous (and not half a minute later). When the contractions first begin, blood flow briefly decreases because of compressive forces exeed by the contracting muscles on the vasculature within the muscle. Each time the muscles contract aerial inflow decreases due to extravascular compression, and then aerial inflow increases as the muscles relax. This is repeated each time the muscles contract and relax. If flow were measured in the outflow vein, the venous outflow would increase during contraction and decrease during relaxation - the opposite of what occurs on the aerial side of the circulation. After just a couple of seconds, mean and peak flows begin to increase. After 15-20 seconds the increased flow will reach a steady state that is determined by the force and frequency of contraction, and the metabolic demands of the tissue. When contractions cease, blood flow may transiently increase because of the loss of compressive forces, and then over the next minute or so the flow will return to control. Blood flow can sometime increase at or even before the sta of exercise. This shows that the initial rise in muscle blood flow in probably a neurally mediated response. Once exercise has staed the high blood flow is maintained by the local mechanisms as described above. Blood flow to brain remains unchanged during exercise. Below given table shows that exercise causes increased blood flow to the exercising muscle with reduction of flow to liver, kidney, GI tract and inactive muscles. Blood flow to the brain remains unchanged. Quiet standing Exercise Cardiac Output 5900 24000 Blood flow to: Hea 250 1000 Brain 750 750 Active skeletal muscle 650 20850 Inactive skeletal ' muscle 650 300 Skin 500 500 Kidney, liver, GIT 3100 600 Lymphatic Flow: The lymphatic system. unlike the circulatory system, has no pump to move lymph fluid. Any form of exercise that incorporates major muscle groups and deep breathing will encourage lymph flow. Muscle movement squeezes lymph vessels.
Category:
Physiology
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