Heart

Structure.

pumps blood into left ventricle from lungs

prevent back flow of blood between atriums and ventricles

pumps blood to rest of body

Contracts to increase pressure

Separates right and left side

pumps blood to the lungs

pumps blood into right ventricle from body

prevents black flow of blood

deoxygenated blood from body

Pumps oxygenated blood to body

Oxygenated blood from lungs

Pumps deoxygenated blood to lungs

Cardiac Cycle.

Atrial Systole. Muscles in atria walls contract blood is forced into ventricles. Semi-lunar valve forced shut and atrioventricular valve opens

Ventricular Systole Muscles in ventricle wall contract Blood is forced out of ventricles Atriventricular valve is forced shut, semi lunar valve is forced open

Diastole Muscles in atria and ventricles relax Blood fills atria and ventricles atrioventricular valve is forced open, semi lunar valve forced shut

Electrical Activity.

Sinoatrial node emits a wave of electricity, this makes the atria contract. A ring of non-conducting tissue prevents further spread it is absorbed by the atrioventricular node. After a short delay it is sent down the bundle of his and across the purkinje fibres, this makes the cardiac muscle contract.

Equations.

Cardiac Output = The volume of blood pumped around the body in a minute. cm3min-1 Stroke Volume = Volume pumped out of the left ventricle in each beat. Heart Rate = beats per minute.

CO = SV x HR

SV = CO

HR

HR = CO

SV

Heart structure

Cardiac cycle

Electrical activity

Key equations