Describe the functions of various parts of the mammalian heart (20mks)
- Pericardial membrane – secretes a lubricating fluid; encloses the heart; prevents over dilation of the heart
- Fat layer – prevents mechanical shock / cushions the heart
- Blood vessels – coronary artery supplies the heart muscles with oxygen and nutrients
- Coronary vein carries away waste products of metabolism
- Valves – prevent back flow of blood into the auricles
- Valve tendons – prevents valves from turning inside out when systolic pressure is high.
- Ventricles – are thick walled to pump blood out of the heart; are hollow to accommodate blood.
- S.A.N (Sino-Atrial Node) – acts as a pace maker to set pace for heart to beat; initiates the rhythmic beating action of the heart.
- Has AVN which receives the contractory wave from the SAN and spreads it to the purkinje tissue which then spreads the wave to the ventricular muscles.
- Cardiac muscles – contract and relax without fatigue
- Vagus nerve – slows down the heartbeat
- Sympathetic – speeds up the hear beat
- Connected to blood vessels which bring in and drain the heart.
(20mks)
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