The heart beats at about 70kpm. It never tires as it rests after every beat.
Cardiac muscle does not need nerves to contract.
When the heart contracts (Systole) it pumps and when it releases (diastole) it fills.
During exercise your heart beets faster and deeper.
Valves ensure one-way flow.
Semi-Lunar valves->
Atrio-ventricular valves
Stop backflow from ventricles during systole.
Valves are NOT muscular, they are opened and closed by differences in blood pressure.
Valve tendons prevent valves from inverting.
Bicuspid has 2 flaps and the tricuspid has 3.

	Criado por Oliver Hall quase 10 anos atrás

Heart Slideshow for IGCSE.