Cardiovascular & respiratory changes during exercise Flashcards
Cardiovascular changes: how does blood redistribute during exercise?
Volume of blood flow diverts to the muscles
to meed increased demands of oxygen!
What are the cardiac changes during exercise?
Physiological changes in exercise
INCREASED cardiac output!
Due to:
- Increased stroke volume- the amount of blood expelled by the heart in each beat.
- Increased heart rate
How is cardiac output increased?
- Increasing sympathetic stimulation & decreasing parasympathetic stimulation increases heart rate.
- Both go to sinoatrial node to increase heart rate - Constriction of veins (in ventricle) due to squeezing action of skeletal muscle on veins > increased venous return
- which increases cardiac output
NOTE: view diagram on notes
How is stroke volume increased?
- Increased sympathetic activity > increased contractility in the ventricle myocardium > increased stroke volume
- Increased cardiac output > increased heart rate & contractibility
- this causes increased stroke volume & pulse pressure - Decreased arterial pressure increases stroke volume
NOTE: view diagram on notes
What is starlings law?
The force of contraction is related to how stretched the cardiac muscle is.
The more full the heart is, the harder it will contract = increase in stoke volume.
How does control shift change during exercise?
During exercise, the control of the heart shifts from mainly parasympathetic to sympathetic
During recovery, there is a shift back.
Muscle changes during exercise?
Increased metabolites (lactate, potassium, adenosine) are produced
- stimulate local vasodilation
- leads to increased blood flow
- thus decreases overall total peripheral resistance
What are the respiratory changes during exercise?
Increase in ventilation rate
Increase in tidal volume- volume of air moving in or out of lungs
*to meet increased oxygen demand!
What are the changes to gases in blood during exercise?
Arterial O₂ and venous CO₂ do not change during exercise.
Enough O₂ is provided by increasing the volume of blood & the speed it gets to the muscles.
How does oxygen consumption change during exercise?
Oxygen consumption increases
- Similar rate for 1st few seconds at different exercise intensities
- Then as exercise intensity increases, demand increases in muscles.
- Demand reaches steady state where lactate acid accumulation is minimal
- Other factors e.g. fuel availability limit exercise.
What does VO₂ max mean?
The maximum rate of oxygen consumption measured during exercise of increasing intensity
- V stands for volume.
Exercising past VO2 max= increased lactic acid accumulation
What factors affect our VO₂ max?
- Age - decreases after 25
- Sex - lower for females
- Activity - improves w/ activity - training can increase our VO₂ max.
What happens to alveolar diffusion capacity during exercise?
O₂ & CO₂ diffusion capacity across alveolar walls INCREASES during exercise.
Caused by an increase in perfusion of blood to the lungs
