Exercise Physiology: Oxygen, Heat and Fluids Flashcards

1
Q

What is oxygen uptake in exercise dependent on?

A

Intensity of exercise

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2
Q

What are the cardiovascular responses to exercise?

A

Increase oxygen supply to skeletal and cardiac muscle
Facilitate carbon dioxide and heat removal
Maintain mean arterial pressure

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3
Q

What is Fick’s equation?

A

VO2 = cardiac output * (CaO2 - CvO2)

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4
Q

Which organ extracts most of the oxygen from arterial blood during exercise?

A

Skeletal muscle

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5
Q

Why can you get post-exercise hypotension?

A

Finish exercise > sudden drop in cardiac output > vessels in legs still dilated > blood pools in legs

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6
Q

Why does the skin vasoconstrict during intense exercise, and why can this be dangerous?

A

Muscle vasodilates > skin vasoconstricts to increase total peripheral resistance and maintain mean arterial pressure
Dangerous because vasoconstriction of skin decreases heat loss

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7
Q

What is exercise hyperaemia?

A

Increase in blood flow to muscles during exercise

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8
Q

What causes exercise hyperaemia?

A

Metabolic vasodilators from contracting skeletal muscle, endothelium, and/or red blood cells
Muscle pump
Conducted vasodilation
Functional sympatholysis

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9
Q

What is conducted vasodilation?

A

Gap junctions spread vasodilation, especially upstream to larger arterioles

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10
Q

What is functional sympatholysis?

A

Alpha receptors on blood vessels normally cause vasoconstriction when activated
Become less effective in exercise because metabolites desensitise them

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11
Q

What is the difference between cardiac output between an athlete and a sedentary person for any given VO2?

A

Not much difference

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12
Q

What is the difference between the heart rate of an athlete and a sedentary person for any given VO2?

A

Lower in athlete

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13
Q

What is the difference between the stroke volume of an athlete and a sedentary person for any given VO2?

A

Higher in athlete

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14
Q

What happens to blood pressure during exercise, and why?

A

Decreased time in diastole, so systole happens more often > increase in blood pressure

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15
Q

What happens to the baroreflex during exercise, and why?

A

Resets to higher level to allow increase in heart rate with increased blood pressure

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16
Q

What is cardiovascular drift during prolonged exercise?

A

Increased heart rate and decreased stroke volume

17
Q

Why does cardiovascular drift occur during prolonged exercise?

A

Hyperthermia
Dehydration
Increased plasma adrenaline
Peripheral displacement of blood volume due to cutaneous vasodilation

18
Q

Why is heart rate lower with exercise in water?

A

Blood stays more central

19
Q

What changes occur in the neural control of circulation during exercise?

A

Increased heart rate in anticipation

Resetting of baroreceptor reflex

20
Q

How does autonomic control increase heart rate during exercise?

A

Early rise because of vagal control

Later, increases because of sympathetic control

21
Q

Why does cardiac output increase after training?

A

Expanded blood volume
Increased heart size
Increased adrenergic sensitivity

22
Q

Why does heart size increase after training?

A

Increased left ventricle mass and chamber size

23
Q

What microvascular adaptations occur after exercise training?

A

Increased capillary density

Increased capillary recruitment

24
Q

What are the respiratory responses to exercise?

A

Maintain arterial oxygen saturation
Carbon dioxide removal
Acid-base balance

25
What proportion of arterial blood is saturated during exercise at sea level in healthy individuals?
Fully oxygenated
26
Under what conditions does arterial desaturation occur during exercise?
High altitude
27
Why may highly trained athletes have arterial desaturation?
Cardiac output may be too fast to fully oxygenate blood
28
What is the main mechanism of heat loss during exercise?
Sweating
29
When is sweating not as effective?
Humid weather
30
What is the relationship between heat stress and exercise capacity and performance?
Heat stress impairs exercise capacity and performance
31
What body fluid compartments are affected in exercise-induced dehydration?
All
32
What is the relationship between dehydration during exercise and performance?
Dehydration impairs performance
33
What is the relationship between exercise performance and prior dehydration?
Prior dehydration impairs exercise performance