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Physiology Ch. 25: Metabolism and Exercise
what does exercise require a steady supply of? and where does it come from?
ATP from metabolism or from conversion of phosphocreatine
how does the most efficient ATP production occur?
what are primary energy substrates?
carbohydrates and fats
how is glucose metabolised?
oxidative and anaerobic pathways
what is required for fatty acid metabolism?
what is caused by lack of oxygen in metabolism?
lactic acid buildup
what converts glucose to lactic acid?
anaerobic glycolytic metabolism
characteristics of glycolytic metabolism?
2.5 times more rapid than aerobic pathways but not as efficient as ATP production
what influences glucose and fatty acid metabolism during exercise?
glucagon, cortisol, catecholamines, growth hormone (they favor the conversion of glycogen to glucose)
which concentrations rise with exercise?
secretion of what decreases during exercise?
what is the significance of the rise in plasma glucose and decrease of insulin secretion during exercise?
glucose uptake by most cells is reduced, making more glucose available for exercising muscle
what indicates the intensity of exercise?
oxygen consumption (a person's maximal rate of oxygen consumption is an indicator of that persons ability to perform endurance exercise)
how long does it take for aerobic exercise to begin mobilizing fat from adipose tissues?
what increases rapidly at the onset of exercise?
what is excess post exercise oxygen consumption due to?
ongoing metabolism, increased body temperature, circulating catecholamines
what increases in size and number with endurance training?
what is the limiting factor dealing with maximal exertion?
the ability of the cardiovascular system to deliver oxygen and nutrients
what does exercise hyperventilation result from?
feed forward signals from the motor cortex, and sensory feedback from peripheral sensory receptors (such as increased plasma K+ levels)
what does not change much during mild to moderate exercise?
why does cardiac output increase with exercise?
because of increased venous return and sympathetic stimulation of heart rate and contractility
when does blood flow through exercising muscle increase dramatically?
when skeletal muscle arterioles dilate and arterioles in other tissues constrict
what acts as paracrines and cause local vasodilation?
decreased tissue O2 and glucose or increased muscle temperature, CO2 and acid
what increases slightly as exercise intensity increases?
mean arterial blood pressure
what prevents significant disruption of homeostasis during exercise?
what area blood flow increase during exercise?
blood flow to the skin
what dissipates heat released during exercise?
sweating and increased blood flow
what can physical activity help prevent?
the risk of developing high blood pressure, strokes, and type 2 diabetes mellitus
how long can phosphocreatine sustain maximal exercise?
how long can anaerobic metabolism support maximal exercise?
how long can aerobic exercise maintain exercise?