Heart Activity Flashcards
What is the cardiac muscle made up of?
Mono nucleated and striated cells which are joined by intercalated disks
How does the heart actually work?
It contracts in a coordinated fashion to ensure blood pumps around the body efficiently and this is achieved by the cardiac conduction system
How does the cardiac conduction system work?
From the sino-atrial (SA) node impulses spread over the atrial muscle causing atrial contractions - electrical impulses are then conducted to the AV node - from the AV node they are spread to the ventricular muscle
How do contractions of the heart occur?
Electrical conduction cause mechanical contractions
What are the events which occur within one heart beat called?
Cardiac cycle
What happens during the cardiac cycle?
The heart contracts and then relaxes
What are the period of contractions known as?
Systole
Diastole
What happens at systole?
Contractions occure
What happens at diastole?
The heart is relaxed and not contracting
How long does systole take?
Atrial- 0.1 seconds
Ventricular - 0.3 seconds
How long does complete diastole take?
0.4 seconds
Why is there an extra 0.2 seconds left after systole and diastole?
To allow for the atria to completely contract and fill again
What does the right atrium receive?
De-oxygenated blood from the body through the superior and inferior vena cava
What does the left ventricle receive?
Oxygenated blood from the lungs through the four pulmonary veins
What is atrial systole?
Contractions of the left and right atria that allow the 30% of blood which does not passive flow into the ventricles to pass through
