Control of Heart Rate Flashcards
How is heart rate controlled?
- SAN initiates heart beat
- Sends an electrical impulse across atria
- Causes atria to contract
- Non-conductive tissue prevents nerve impulses reaching the ventricles
- Impulse arrives at AVN
- AVN delays the impulse to allow atria to contract and empty before the ventricles contract
- AVN sends impulse down the impulse down the bundle of His to the Purkyne fibres
- Causes ventricles to contract from the base up
How is the left ventricle different to the right ventricle?
- Highest blood pressure
- Most cardiac muscle
- Contracts with greatest force
- Pumps blood to whole body
What happens to the atria during atrial systole?
They are contracted and at high pressure
What happens to the ventricles during atrial systole?
They are relaxed and at low pressure
What happens to the atrioventricular valves during atrial systole?
Open
What happens to the semilunar valves during atrial systole?
Closed
What happens to the atria during ventricular systole?
They are relaxed and at low pressure
What happens to the ventricles during ventricular systole?
They are contracted and at high pressure
What happens to the atrioventricular valves during ventricular systole?
Closed
What happens to the semilunar valves during ventricular systole?
Open
What happens to the atria during diastole?
They are relaxed and at low filling pressure
What happens to the ventricles during diastole?
They are relaxed and at low lower pressure
What happens to the atrioventricular valves during diastole?
Open
What happens to the semilunar valves during diastole?
Closed
