Cardiac dynamics Flashcards
Define stroke volume
Volume of blood ejected from the heart per beat
What is stroke volume measured in
ml
Define heart rate
Number of times the heart beats per min
What is heart rate measured in
bpm
Define cardiac output
Volume of blood ejected from the heart per minute
What is cardiac output measured in
l/min
How can max HR be calculated
220-age
What is bradycardia
HR under 60bpm
What is anticipatory rise
Slight rise in HR before exercise due to adrenaline
What happens to HR during exercise
Rises proportionately to intensity, rapid increase until steady state reached
What happens to HR post exercise
Initially drops due to less O2 demand, gradual drop to repay O2 debt
When does stroke volume occur
Ventricular systole (pumping out)
What is a regular stroke volume for untrained athletes at rest
60-90ml per beat
What is a regular stroke volume for trained athletes at rest
90-110ml per beat
What is a regular stroke volume for untrained athletes at sub maximal exercise
120-140ml per beat
What is a regular stroke volume for trained athletes at sub maximal exercise
160-200ml per beat
What is a regular stroke volume for untrained athletes at maximal exercise
Slight decrease from sub maximal
What is a regular stroke volume for trained athletes at maximal exercise
Slight decrease from sub maximal
Why does stroke volume decrease at max intensity
Firing rate of SA node increases due to reduced time for heart to fill
What are 2 reasons that stroke volume increases
Increased venous return (greater diastolic filling)
Starlings law (more blood to heart leads to greater end diastolic volume)
What is ejection fraction
How much of the potential blood in left ventricle is ejected per beat
What is a normal ejection fraction %, and what is too high
Normal - 50-70%
Too high - 75%+ (heart condition)
What is the formula for cardiac output
Cardiac output (Q) = Heart rate (HR) x Stroke volume (SV)
What is a regular cardiac output for untrained athletes at rest
5L/min
