Cardiac Cycle Flashcards
(22 cards)
What are the three stages the cardiac cycle is split into?
Diastole
Atrial Systole
Ventricular Systole
What does diastole mean?
Relaxing
What does systole mean?
Contracting
How do you calculate cardiac output?
Heart rate x Stroke volume
What is heart rate?
Beats of the heart per minute.
What is stroke volume?
Volume of blood that leaves the heart each beat.
What is cardiac output?
The volume of blood which leaves one ventricle in one minute.
What do valves do?
Ensure that blood flows in the correct direction and doesn’t flow back into the atria.
What are the two types of valves?
Semilunar and atrioventricular
Where are semilunar valves?
In the aorta and pulmonary artery.
Where are the atrioventricular valves?
Between the atria and ventricles.
What are the two types of atrioventricular valves?
Bicuspid (2 flaps) on the left side.
Tricuspid (3 flaps) on the right.
What is another word for bicuspid?
Mitral
When do valves open?
When pressure is higher behind the valve.
When do valves close?
When pressure is higher in front of the valve.
When do atrioventricular valves open?
When pressure is higher in the atria compared to the ventricles.
When do atrioventricular valves close?
When pressure is higher in the ventricles compared to the atria. To prevent backflow of blood.
When do semilunar valves open?
When there is a higher pressure behind (in the ventricles) compared to the arteries (pulmonary artery or aorta).
When do semilunar valves close?
When there is a higher pressure in front (in arteries - in the pulmonary artery or aorta) compared to the ventricles. To prevent backflow of blood.
Describe atrial systole.
Atria contract. So their volume decreases and pressure increases. AV valves open when pressure in atria exceeds pressure in ventricles. SL valves remain shut as pressure in arteries exceeds pressure in ventricles. So blood is pushed into ventricles.
Describe ventricular systole.
Ventricles contract. So their volume decreases and pressure increases. AV valves shut when pressure in ventricles exceeds pressure in atria. SL valves open when pressure in ventricles exceeds pressure in arteries. So blood pushed out of heart through arteries.
Describe diastole.
Atria and ventricles relax. So their volume increases and pressure decreases. SL valves shut when pressure in arteries exceeds pressure in ventricles. AV valves open when pressure in atria exceeds pressure in ventricles. So blood fills atria via veins and flows passively to ventricles.
