Sue - The Heart Flashcards
Cardiac Output (Q) =
Stroke Volume (SV) x Heart Rate (HR)
The amount of blood pumped out by the ventricle in each contraction
Cardiac Output
The amount of blood pumped out by the left ventricle in each contraction
Stroke Volume
The number of times the heart beats per minute
Heart Rate
During exercise, cardiac output will…
increase until maximum intensity is reached and then it plateau’s
When someone has a lower resting heart rate below 60 beats per minute
Bradycardia
An increase in size and growth of skeletal muscles
Hypertrophy
Why does Stroke volume increase while exercise does up to 40-60 % of maximum effort?
As once the performer reaches this point the ventricles do not have as much to fill up with blood due to an increased HR, causing a plateau
Explain cardiovascular drift?
When there is an increase in heart rate and a decrease in stroke volume due to prolonged exercise in warm conditions
Caused by reduction of fluid in the blood plasma due to increase in sweating so the blood becomes more viscous and so HR decreases > poor hydration
How does the the heart initiate a heart beat?
SAN > Atrial systole (contraction) > AVN > Bundle of His > Bundle branches > Purkinje fibres > Ventricular systole
Starlings Law order?
- Increased VENOUS RETURN (due to veins being squeezed during exercise)
- Leads to a greater diastolic filling so the cardiac muscle is STRETCHED
- More powerful force of contraction
- which increases the EJECTION FRACTION
- Increase in STROKE VOLUME
A stress hormone that is released by the sympathetic nerves and cardiac nerve during exercise
Adrenaline
What effect does Adrenaline have?
It stimulates the SAN which results in an increase in both SPEED and FORCE of contraction, thereby increasing cardiac output. More blood is pumped to the working muscles so they can receive more oxygen for the energy they need.
A nervous system that stimulates the heart to beat faster
Sympathetic
A nervous system that returns the heart to its resting level
Parasympathetic