Cardiovascular System - Lecture 10 Flashcards
What happens to the cardiovascular effects of exercise? (2)
- sustained (steady state)
- O2 used = O2 taken in
What happens to HR during exercise?
it increases
HR during exercise is proportional to what?
work
How can you find your Max HR?
220-age (variable) and decreases as a function of your age
How much can your HR change during exercise?
3x or more (60 to 180 BPM)
Why does HR increase during exercise?
due to increase in sympathetic tone and decrease in parasympathetic tone
What happens to stroke volume during exercise?
it increases a little (in the situation in the notes, it dips)
What increases contractility in stroke volume during exercise?
sympathetic activity
At very high heart rates there is usually a ___ in SV.
fall
Why is there a fall in SV at very high heart rates?
- decrease systole
- diastolic period shortens much more
- filling time decreases
What happens to cardiac output during exercise?
it goes up linearly
What does CO mostly depend on during exercise?
HR
What is the factor for both HR and CO?
3
What does circulating epinephrine bind to on the SA node to increase HR and contractility?
b-receptors
What happens to MAP during exercise?
it increases a bit (20%)
What is the factor of increase in MAP compared to CO?
1.2 compared to 3
What happens to diastolic AP during exercise?
almost no increase
What happens to systole AP during exercise?
increases from 120 to 190
What do you check during the cardiac ‘stress test’?
make sure the systolic rises to a high level (around 200 mmHg)
- measures the ventricles ability to generate force
What does low force during cardiac stress test indicate?
damage to ventricles (scar tissue)
What happens to TPR during exercise?
it drops 40% its resting value
Why does TPR drop during exercise?
because muscles consume more O2 and generate waste products: metabolic autoregulation
What happens to oxygen consumption during exercise?
it rises by around 9x
Why does oxygen consumption increase by 9x?
Oxygen consumption increase due to 3x increase in CO and a 3x increase in the amount of O2 extracted (3x arteriovenous O2 difference).
What is the ranking of increased blood flow during exercise?
- muscle
- skin
- heart
- elsewhere
What factor does blood flow increase in muscle during exercise?
12x
What factor does blood flow increase in skin during exercise?
5x
What factor does blood flow increase in the heart during exercise?
3.5x
Why is there a drop in the rest of the body during exercise?
because MAP is almost constant which compensates for increase
Norepinephrine is a potent ___ agonist.
alpha
Epinephrine is a ___ agonist.
beta
What receptor activation balance determines tone at rest?
alpha beta receptor activation
What happens in non-exercising muscle and most organs during exercise?
- alpha»beta = constriction
- R increases
T or F:
Non-exercise muscle does experience vasoconstriction in arterioles during exercise.
true
What 3 substances increases vasoconstriction in alpha receptors?
plasma norepinephrine, norepinephrine in ECF, plasma epinephrine
Which receptor causes vasoconstriction?
alpha
Which substance increases vasodilation in beta receptors?
plasma epinephrine
T or F:
Training has an effect on max heart rate.
false, it has no effect on max heart rate
What happens to stroke volume and heart rate during a few weeks of aerobic training?
SV: increases
HR: doesnt increase
What happens to contractility during endurance training?
it increases
What happens to hypertrophy, SV and resting HR during endurance training when contractility increases?
hypertrophy: increases
SV: increases
resting HR: falls
