What happens during atrial systole?

The atria contract, increasing atrial pressure and pushing blood through open atrioventricular valves into the ventricles.

What happens during ventricular systole?

The ventricles contract, increasing ventricular pressure which closes the atrioventricular valves and opens the semilunar valves, ejecting blood into arteries.

What happens during diastole?

The heart muscle relaxes, ventricular pressure falls below arterial pressure causing semilunar valves to close, and blood flows passively from veins into atria and ventricles.

What causes the atrioventricular valves to close?

They close when ventricular pressure exceeds atrial pressure, preventing backflow into the atria.

What causes the semilunar valves to close?

They close when arterial pressure exceeds ventricular pressure, preventing backflow into the ventricles.

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Transport in Animals

The cardiac cycle and control of the heartbeat

1 thing to know
Components 01 and 03

Overview

Atrial systole, ventricular systole and diastole, what opens and closes the valves, the cardiac output calculation, and the route from sino-atrial node to Purkyne tissue.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Process

How is the heartbeat coordinated?

Questions from this subtopic

Each one with the model answer underneath.

1
Name the three stages of the cardiac cycle.
Model answer
Atrial systole, ventricular systole, and diastole.
2
What happens during atrial systole?
Model answer
The atria contract, increasing atrial pressure and pushing blood through open atrioventricular valves into the ventricles.
3
What happens during ventricular systole?
Model answer
The ventricles contract, increasing ventricular pressure which closes the atrioventricular valves and opens the semilunar valves, ejecting blood into arteries.
4
What happens during diastole?
Model answer
The heart muscle relaxes, ventricular pressure falls below arterial pressure causing semilunar valves to close, and blood flows passively from veins into atria and ventricles.
5
What causes the atrioventricular valves to close?
Model answer
They close when ventricular pressure exceeds atrial pressure, preventing backflow into the atria.
6
What causes the semilunar valves to close?
Model answer
They close when arterial pressure exceeds ventricular pressure, preventing backflow into the ventricles.

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