How is a mammalian heart structurally adapted to its function?

K.C.S.E Biology Q & A - MODEL 2015PP2QN08

How is a mammalian heart structurally adapted to its function?

ANSWERS

•  Has cardiac muscles; which contract and relax continuously/without fatigue;
•  Cardiac muscles are interconnected/form a network of fibres; to rapidly and uniformly spread the contractions;
•  Divided into four chambers; for the atria to receive blood and ventrical to pump blood out of the heart.
•  Divided into two sides by a longitudinal septum; to prevent mixing of oxygenated and deoxygenated blood;
• Ventricles have thicker walls; to generate high pressure to pump blood;
• Wall of left ventricle are thicker than those of right ventricle; to pump blood over a longer distance;
• Has valves; to prevent back flow of blood for double circulation;
• Cuspid valves have strands of connective tissues/cordaetandinae/tendinous; to prevent the valves from turning inside out during systole when ventricles contract;
• Has coronary artery to nourish/supply oxygen/nutrients the heart muscles;
• Has coronary vein; to remove metabolic wastes;
• Enclosed by a pericardium; to keep it in position/prevent overdilation;
• Pericardium is externally surrounded with a layer of fats; to cushion the heart against mechanical damage;
• Pericardium secretes pericardial fluid; to reduce friction/absorb shock;
• Has Sino Atrio Node (SAN); which acts as a pace maker;
• Has Atrio Ventricular Node (AVN); which relays contraction waves from Sino Atrio Node to the purkinje tissue;
• Has purkinje tissue/bundle of RS; to relay waves from Atrio Ventricular Node; to the ventricular myocardium;
• Cardiac muscles have numerous mitochondria; to generate energy for the muscular contractions;
• Vena cava and pulmonary vein; supply blood to the heart;
• Aorta and pulmonary artery; transport blood away from the heart.