Exercise physiology
From Iusmphysiology
Revision as of 01:04, 20 April 2011 by 24.15.60.132 (Talk)
- started here on 04/11/11.
Contents |
Exercise physiology
Objectives
- The student will be able to describe the 3 metabolic systems that supply energy during exercise and relate exercise conditions with nutrient fuel use.
- The student will understand how oxygen consumption varies with exercise intensity.
- The student will be able to describe the 2 stages of oxygen recovery.
- The student will be able to describe respiratory changes during exercise.
- The student will be able to describe chemical and neural mechanisms stimulating ventilation during exercise.
- The student will be able to describe the dynamic relationship between changes in stroke volume and heart rate during exercise.
- The student will be able to describe the redistribution of blood flow to muscles and other organs during exercise.
- The student will understand the unique regulation of temperature during exercise.
- The student will understand the effect of training on cardiovascular, respiratory and metabolic function.
Metabolic aspects of exercise
- Exercise requires lots of ATP for all the work the muscle is doing.
- ATP can be generated in three ways: the phosphagen system, the glycogen-lactic acid system, or the aerobic system.
- The phosphagen system uses creatine kinase to move the phosphate group off of creatine to ADP, generating ATP.
- The phosphagen system (and the resident ATP) covers the energy for the 0-60 seconds of vigorous exercise.
- The glycogen-lactic acid system runs glycogen through glycolysis to generate lactic acid.
- The glycogen-lactic acid system covers the energy for the 1-4 minutes of vigorous activity.
- The aerobic system uses the electron transport chain to generate ATP from glucose, fatty acids, and amino acids.
- Aerobic oxidation of muscle glycogen, plasma glucose, and liver glycogen cover the energy for minutes 4-200 (and then tapers off).
- Aerobic oxidation of plasma FFA (free fatty acids) and adipose tissue TAGs (triacylglycerides) cover the energy for minutes 45 and beyond.
- The phosphagen system uses creatine kinase to move the phosphate group off of creatine to ADP, generating ATP.
Energy conversion in skeletal muscle
- Recall that glycolysis takes glucose to two pyruvate molecules, generating 6 ATP and 2 NADH.
- Recall that bursts of heavy activity utilize the phosphagen system and the glycogen-lactic acid systems for production of ATP.
Energy suply to muscle during exercise
- During exercise, epinephrine is elevated which signals to the liver, skeletal muscle, and adipose tissue.
- Epinephrine at the liver:
- Epinephrine causes the liver to increase glycogenolysis and gluconeogenesis.
- Epi--like glucagon--binds to a receptor that elevates cAMP levels and thus triggers activation of appropriate enzymes.
- Note that gluconeogenesis can use lactic acid as a precursor to be converted into glucose.
- Epinephrine at the muscle:
- Epinephrine at the skeletal muscle signals for the use of glycolysis (the anaerobic burning of glucose).
- Epinephrine binds to a cAMP elevating receptor on skeletal muscle which leads to activation of appropriate enzymes for converting glucose into ATP and aerobic intermiediates (think NADH and pyruvate).
- Glucose converted to pyruvate too quickly to be used in the (limited capacity citric acid cycle--oxphos) can be converted to lactic acid and secreted into the blood to be used in gluconeogenesis at the liver.
- Recall that this loop (glucose -> pyruvate (to get the ATP and NADH) -> lactic acid -> liver -> glucose -> muscle -> pyruvate...) is called the cori cycle.
- Epinephrine at the adipose tissue:
- Epinephrine at the adipose tissue causes TAG breakdown into FFAs for secretion into the blood.
- Epinephrine binds to a receptor that activates the hormone-sensitive lipase.
Oxygen consumption during exercise
- The basal rate of oxygen consumption is about 0.25 L / minute.
- Light exercise can elevate oxygen consumption 3-fold to about 1 liter.
- Heavy exercise can elevate oxygen consumption 8-10 fold to nearly 3.5 liters.
VO2: Maxiumum O2 consumption
- stopped here on 04/11/11.
- started here on 04/12/11.
Objectives
- The student will be able to describe the 3 metabolic systems that supply energy during exercise and relate exercise conditions with nutrient fuel use.
- The student will understand how oxygen consumption varies with exercise intensity.
- The student will be able to describe the 2 stages of oxygen recovery.
- The student will be able to describe respiratory changes during exercise.
- The student will be able to describe chemical and neural mechanisms stimulating ventilation during exercise.
- The student will be able to describe the dynamic relationship between changes in stroke volume and heart rate during exercise.
- The student will be able to describe the redistribution of blood flow to muscles and other organs during exercise.
- The student will understand the unique regulation of temperature during exercise.
- The student will understand the effect of training on cardiovascular, respiratory and metabolic function.
- stopped here on 04/12/11.