EXAM #1: PULMONARY EXERCISE PHYSIOLOGY

Question 1

Write the basic equations that describe the energy requirements of exercise.

Answer 1

N/A

Question 2

What are the three ways that the SNS modulates exercise?

Answer 2

1) Increase HR
2) Increase TPR
3) Increase contractility, which increases SV

Question 3

Why is there higher SNS output during exercise?

Answer 3

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

Question 4

What is central command?

Answer 4

High motor center increase in BR set point

*Note that this also goes to the respiratory system to increase respiratory rate

Question 5

What is the exercise pressor reflex sensing?

Answer 5

1) Metabolites produced from exercise (Gp IV afferents)
2) Speed and force of muscle contraction (Gp III afferents)

*Both work to increase the SNS

Question 6

How much of perfusion can be redirected to muscle in vigorous exercise?

Answer 6

80%

Question 7

Why do skeletal muscles NOT vasoconstrict in response to vigorous exercise?

Answer 7

Functional sympatholysis i.e. metabolites produced in muscles during exercise cause vasodilation

Question 8

What is the equation for MAP?

Answer 8

CO x TPR

Question 9

Why is there an increase in systolic pressure in exercise, but not diastolic?

Answer 9

• 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

Question 10

How does arm exercise compare to leg exercise?

Answer 10

1) Increase HR response
2) Greater pulmonary vent.
3) Higher perceived exertion

Thus, there is an increased BP during arm exercise vs. leg exercise

Question 11

Why can VO2 max be estimated from HR?

Answer 11

HR increases correspondingly with work rate

Question 12

What is the 6MWT?

Answer 12

Best distance walked in m over a 6min period

Question 13

Why is there increased SV during exercise?

Answer 13

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)

Question 14

How does avO2 change with exercise?

Answer 14

Increases b/c venous oxygen content goes down

• Increase muscle work= increased oxygen extraction
• Venous oxygen content drops

Question 15

Does the hypothalamic set-point change during exercise?

Answer 15

No

Question 16

How does the body respond to the increased heat generated by exercise?

Answer 16

1) Cutaneous dilation
2) Sweating, which evaporates

*SV decreases, dropping CO and BP (this is exacerbated by sweating)

Question 17

How is the circulation to the skin described?

Answer 17

“Complaint”

Question 18

How does the body compensate for the effects caused by cutaneous vasodilation when exercising in the heat?

Answer 18

Increased CO by increasing HR; thus, exercising in the heat puts a strain on the heart

Question 19

What sets the respiratory threshold?

Answer 19

Lactate threshold

Question 20

List five metabolic adaptations to exercise.

Answer 20

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