Describe the functions of various parts of the mammalian heart (20mks)

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  • 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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