Cardiac Dynamic Flashcards
Stroke Volume
The volume of blood ejected from the left ventricle per beat (ml)
Heart Rate
The number of times the heart beats per minute (bpm)
Cardiac Output
The volume of blood ejected (pumped) from the heart per minute (l/min)
Average bpm
72 bpm
What is a heart rate under 60 called
Bradycardia
How is your max heart rate calculated
220 - age children
Why does heart rate rise slightly before exercise ?
Due to adrenaline - anticipatory rise
During exercise ( heart rate )
HR will rise proportionally to exercise intensity - At sub-maximal levels HR will plateau when a steady state is reached and O2 demand is met
Post exercise ( heart rate )
Initial rapid drop in HR due to less oxygen demand
When does stroke volume (SV) occur
During the ventricular systole
What is the average resting SV
70 ml
What can stroke volume depend on
Venous Return - Starling’s Law
What is the difference between a trained and untrained resting SV
Untrained - 60 - 90 ml/bpm
Trained - 90 - 110 ml/bpm
Why does SV decrease slightly at maximal exercise
Due to increased firing rate of SA node
Why does SV increase
Increased venous return - increased blood back to the heart - leads to greater diastolic filling ( heart filling up when relaxing)
Starling’s Law - more blood to the heart - leads to greater diastolic volume - great stretch of atria walls - leads to more forceful contractions
