The Cardiac Cycle Flashcards
what are three three stages of the cardiac cycle
diastole
atrial systole
ventricular systole
what does diastole mean
relaxing
what does systole mean
contracting
describe the first stage (diastole)
- atria and ventricular muscles are relaxed
- blood enters the atria via the pulmonary vein and vena cava
- blood flowing in means the pressure increases whilst volume decreases
describe atrial systole stage
- atria muscle contract as the pressure increases and volume decrease
- the build up of pressure behind the AV valves causes them to open
- blood starts flowing into the ventricles
describe the ventricular systole
- ventricle muscles start to contract which causes an increase in pressure and decrease in volume significantly
- this causes AV valves to shut and SL valves to open
- blood pushes out of the ventricles through to the pulmonary artery and aorta
whats the equation for cardiac output
heart rate x stroke volume
whats the cardiac output
the volume of blood which leaves one ventricle in one minute
what is the heart rate
beats of the heart per minute
what is the stroke volume
the volume of blood that leaves the heart each time it beats
where are the semi lunar valves
in aorta and pulmonary artery
where’s the atrioventricular valves
between atria and ventricles
how does pressure control the opening and closing of the valves
- they open when the pressure is high behind the valve
- they close when the pressure is high in front of the valve
when will the AV valves open
when the pressure is higher in the atria compared to the ventricles
when will the AV valves close
when pressure is higher in ventricles than in the atria
