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Explain how the mammalian heart is structurally adapted to its functions.

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  1. It has cardiac muscles which are myogenic, (does not need nervous stimulation) for pumping of blood.
  2. It connected to vagus and sympathetic nerves; which controls the rate of heart beat depending on the body’s physiological requirements.
  3. It has tricuspid and bicuspid valves between articles and ventricles which prevents back flow of blood into the right and left ventricles respectively.
  4. The heart is connected to the coronary artery; which supplies food and oxygen to the cardiac muscles for the pumping action.
  5. The coronary vein in the heart; is used to remove metabolic wastes.
  6. The heart is divided into two by atrio-ventricular septum; which prevents mixing of oxygenated blood and deoxygenated blood.
  7. The heart is enclosed by the pericardial membrane that secretes pericardial fluid which prevents friction in the walls during pumping.
  8. The outer pericardium layer surrounded by a layer of fat; to act as shock absorbers thus protecting it from mechanical damage.
  9. It has sino atrial node (S.A.N) to act as a pace maker by regulating the rate of beating and excitation of the heart.
  10. The walls of the left ventricle are thicker than those of the right ventricles, to generate more pressure to pump blood over longer distance to the rest of the body.
  11. The tricuspid and bicuspid valves are held by tendrons; which prevents the valves from turning inside out during ventricular contractions.
  12. The heart is joined by blood vessels aorta distributes blood to all body tissues except the lungs.
  13. Pulmonary artery which leaves the heart/left ventricle carries deoxygenated blood to the lungs.
  14. Pulmonary vein entering the heart /left atrium convey oxygenated blood form the lungs to the heart.
  15. Vena cava entering the right atrium brings in de-oxygenated blood from body tissues.
  16. Semi lunar valve at the base of the aorta and pulmonary artery; prevents back flow of blood to the ventricles once it has been pumped out.
  17. The cardiac muscles of the heart never get fatigued hence the rhythmic contractions goes on throughout life.
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