EXAM #1: PULMONARY EXERCISE PHYSIOLOGY Flashcards
Write the basic equations that describe the energy requirements of exercise.
N/A
What are the three ways that the SNS modulates exercise?
1) Increase HR
2) Increase TPR
3) Increase contractility, which increases SV
Why is there higher SNS output during exercise?
Baroreceptor reflex is reset to a higher set point to allow for higher HP b/c of:
1) Central command–feedforward
2) Exercise pressor reflex–feedback
What is central command?
High motor center increase in BR set point
*Note that this also goes to the respiratory system to increase respiratory rate
What is the exercise pressor reflex sensing?
1) Metabolites produced from exercise (Gp IV afferents)
2) Speed and force of muscle contraction (Gp III afferents)
*Both work to increase the SNS
How much of perfusion can be redirected to muscle in vigorous exercise?
80%
Why do skeletal muscles NOT vasoconstrict in response to vigorous exercise?
Functional sympatholysis i.e. metabolites produced in muscles during exercise cause vasodilation
What is the equation for MAP?
CO x TPR
Why is there an increase in systolic pressure in exercise, but not diastolic?
- Systolic pressure is determined centrally
- Diastolic pressure is determined peripherally
*Thus, b/c there is metabolite induced vasodilation in the skeletal muscles, diastolic pressure remains low during exercise
How does arm exercise compare to leg exercise?
1) Increase HR response
2) Greater pulmonary vent.
3) Higher perceived exertion
Thus, there is an increased BP during arm exercise vs. leg exercise
Why can VO2 max be estimated from HR?
HR increases correspondingly with work rate
What is the 6MWT?
Best distance walked in m over a 6min period
Why is there increased SV during exercise?
1) Increased venous return from:
- Muscle pumping action
- Respiratory effect (intrathroacic pressure)
2) Increased SNS on cardiac muscle (Ca++ induced Ca++ release)
3) Decreased TPR from vasodilation in skeletal muscle (metabolite induced)
How does avO2 change with exercise?
Increases b/c venous oxygen content goes down
- Increase muscle work= increased oxygen extraction
- Venous oxygen content drops
Does the hypothalamic set-point change during exercise?
No
How does the body respond to the increased heat generated by exercise?
1) Cutaneous dilation
2) Sweating, which evaporates
*SV decreases, dropping CO and BP (this is exacerbated by sweating)
How is the circulation to the skin described?
“Complaint”
How does the body compensate for the effects caused by cutaneous vasodilation when exercising in the heat?
Increased CO by increasing HR; thus, exercising in the heat puts a strain on the heart
What sets the respiratory threshold?
Lactate threshold
List five metabolic adaptations to exercise.
1) Increased mitochondria
2) Increased capillary density
3) Glucose sparing (utilize fat over sugar)
4) Improved blood lactate clearance
5) Insulin sensitivity*
*Increased insulin sensitivity occurs in response to exercise
