3.1.2: Cardiac Cycle Flashcards
What is the cardiac cycle?
A series of contractions (systole) and relaxation (diastole) of the cardiac muscle, resulting in pressure and volume changes that cause valve movements to maintain a unidirectional flow of blood.
What happens during atrial systole?
The atria contract, increasing pressure in the atria, opening the atrioventricular valves, and forcing blood into the ventricles.
What is ventricular systole?
The phase when the ventricles contract and the atria relax, increasing pressure in the ventricles, causing atrioventricular valves to shut and semilunar valves to open.
What is the result of ventricular systole?
Blood flows out of the ventricles and into the pulmonary artery and aorta.
What are the atrioventricular valves?
Valves that open during atrial systole and close during ventricular systole.
What are semilunar valves?
Valves that open during ventricular systole and close at the end of this phase.
What is heart rate?
A measure of how many times the heart beats per minute.
What is stroke volume?
The volume of blood pumped by the heart in one beat.
How is cardiac output calculated?
Cardiac output = stroke volume X heart rate.
What is the role of the sinoatrial node (SAN)?
Known as the pacemaker, it releases a wave of depolarisation across the atria, causing contraction.
Where is the atrioventricular node (AVN) located?
Near the border of the right and left ventricle within the atria.
What is myogenic contraction?
Contraction initiated by cardiac muscle itself, but controlled by electrical activity.
Fill in the blank: The first heart sound is often referred to as _______.
[Lub]
Fill in the blank: The second heart sound is often referred to as _______.
[Dub]
True or False: The atrioventricular valves open when there is higher pressure behind them.
True
What is the function of the cardiac muscle during diastole?
Filling phase when the heart muscles relax.
