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What do muscles use ATP for?
Muscles require ATP for crossbridge movement, Ca2+ reuptake and Na+/K+ ATPase
What are the three main fuel sources in muscle and how do they differ in the amount of ATP produced and the amount of time they last?
- Muscle Phosphocreatine (PCr) - last ~15 sec.
- Anaerobic Glycolysis - Small Amounts of ATP very quickly
- Beta-Oxidation - Slow but yields lots of energy
What are three main muscle types?
- Fast twitch Glycolitic
- Fast twitch oxidative-glycolitic
- Slow twitch oxidative
How are the three main muscle types physiologically different? (speed of action, force production, endurance)
- Fast Twitch Glycolitic - Large fibers, fewer blood vessels, little myoglobin; High Speed and Force
- Fast Twitch Oxidative-Glycolitic - intermediate
- Slow Twitch Oxidative - Small diameter, many blood vessels, high myoglobin; High endurance
How does Aerobic training alter muscle?
- Increases fat and glycogen stores within muscles
- Increase activity of Beta Oxidation enzymes
- Changes relative composition of fiber types
What is the Oxygen Debt and what is it used for?
- a cumulative deficit of oxygen resulting from intense exercise; the deficit must be made up when the body returns to rest.
- Used to increase ATP production. Must be made up to:
- restore muscle ATP
- restore muscle PCr
- replenish myoglobin O2metabolize lactate
What are VOmax and Factorial aerobic scope? What is the normal range for factorial scope?
- VOmax is the maximum oxygmen capacity
- (aerobic) scope is the ratio f VO2max to oxygen consumption at rest
- Normal is about 10-11
What are the stimuli for control of ventilation, where are they sensed, and how do they affect ventilation?
- Stimulated by low PO2, low pH, and high PCO2 (sensed by glomus cells)
- Stimulated by high [H+] concentration (sensed by central chemoreceptors)
- Both depth and rate of ventilation are increased during exercise
What effects does training hve on the ventilatory system?
- Primarily, it increases the lactate threshold, which in the exercise intensity at which lactate starts to accumulate in the blood.
- Can also have very slight effect on the endurance of the respiratory muscles themselves
How does exercise affect the Hb-O2 dissociation curve and therefore delivery of oxygen to tissues?
Increasing PCO2, increasing temperature, increasing 2,3-DPG, and increased acidity (decreased pH) all shift the Hb-O2 curve to the right, resulting in more unloading of oxygen in tissues.
How is blood redistributed during exercise?
Blood is pooled away from the gut, muscles and kidneys so that it can primarily perfuse the muscles
What happens to cardiac output, heart rate, and stroke volume during exercise?
Cardiac output increases due to increased HR and SV
How are heart rate and stroke volume controlled.
- HR is increased to ~100 bpm by released of parasympathetic inhibition of the sinoatrial node. It is further incresed above 100 bpm by sympathetic control\
- SV is increased by increasing the force of contraction and end-diastolic volume (venous return). Venous return in increased by skeletal muscle and respiratory pumps and by peripheral vasoconstriction
Why doesn't the baroreceptor reflex cause peripheral vasoconstriction during exercise?
- Mean Arterial Pressure increased despite large decreases in Total Peripheral Resistance b/c:
- 1) The motor cortex resets the baroreceptor threshold
- 2) Baroreceptor afferents are inhibited
- 3) Muscle chemoreceptors (responding to metabolites) trigger CNS to override baroreceptors
How does training affect the cardiovascular system?
In affects it primarily by increasing cardiac output through effects on stroke volume. Dynamic exercise leads to a large left ventricle (increased venous return), whereas isometric lead to a more muscular left ventricle (increased force of contraction)
What are some major effects of regular exercise on long term health?
- Regular exercise can increase HDL:LDL, lower resting blood pressure, and increase maximal oxygen uptake.
- Reduce risk of type II diabetes
What is the effect of regular exercise on insulin sensitivity?
Regular exercise can remove glucose from the blood more quickly and with much less insulin (=increased insulin sensitivity) than people who are sedentary. Thus regular exercise can reduce your risk of developing Type II Diabetes