CV changes during exercise Flashcards
The 5-6 fold increase in cardiac output during exercise is due to an increase in what?
Stroke volume
Why is there a decrease in TPR during exercise?
Vasodilation in active muscle
Why is there a decrease in VO2 during exercise?
More blood is being redistributed to the tissues
At what 2 locations does SNS stimulation during exercise cause vasoconstriction?
- Arterioles to decrease flow to non-active muscle
2. Veins to increase MCFP which increases VR
During exercise, does AO2 increase or decrease?
Stays relatively constant
There is a greater AVO2 difference during exercise due to which variable changing?
VO2 decreasing
SNS stimulation during exercise is due to what 3 things?
- Cerebral cortex stimulation
- Reflex signals from active joint receptors & muscle spindles
- Local chemoreceptor signals originating in the active muscle
The SNS effects of increased HR and SV (CO) during exercise induce vasoconstriction or vasodilation at the heart?
Vasodilation from local metabolic factors
How do we maintain slightly increased blood pressure during exercise?
SNS stimulation of vascular smooth muscle in walls of arteries
Do the brain and lungs have a strong vasocontrictor response from SNS stimulation?
NO, weak response that doesn’t limit blood flow (we don’t want to reduce blood flow to these areas!)
What is the increase in SBP during exercise due to?
Increased CO
Is the increase in SBP larger, equal to, or smaller than the decrease in TPR during exercise?
Greater than
What changes occur to DBP during exercise?
Slight increase, may decrease
What changes occur to pulse pressure during exercise?
Increase because the increase in SBP is larger than the change in DBP
Is the increased blood flow to the active muscle during exercise due to SNS?
NO! Due to local release of tissue metabolites in response to the increase in metabolism
-Adenosine, CO2, K, histamine, lactic acid
What are the only 2 CV factors to decrease during exercise?
TPR and VO2
What is VO2 max?
The maximum volume of oxygen that one can take up from the lungs and deliver to the tissues per minute
What is VO2 max a function of?
CO and AV O2 difference
What occurs if energy demands of exercise cannot be met by oxidative phosphorylation?
Oxygen debt (respiration remains elevated after exercise to repay debt)
Extra O2 is used in oxygen debt to:
Restore metabolite levels
Metabolize lactate generated by glycolysis
How do we maintain slightly increased blood pressure during exercise?
SNS stimulation of vascular smooth muscle in the walls of arteries
Do the lungs and brain have strong vasocontrictor responses due to SNS stimulation?
NO, weak constrictor response that doesn’t limit blood flow
we don’t want to reduce blood flow to these areas!
What happens to pulse pressure during exercise?
Increases (because the increase in SBP is larger than the increase in DBP)
What is the increase in SBP during exercise due to?
Increased CO
Is the increase in SBP during exercise larger or smaller or equal to the decrease in TPR?
Larger
