describe the adaption of the mammalian heart to its function
Answers
Explain how the mammalian heart is adapted to perform its function. (mks)
- Muscular to pump blood over long distance;
- Myogenic cardiac muscles which contract and relax rhythmically without fatigue; hence heart continues pumping;
- Cardiac muscle fibres interconnected to form a network of fibre to ensure rapid and uniform spread of excitation throughout the walls of the heart;
- Heart divided into 4 chambers which are hollow to accommodate more blood;
- Ventricles have thicker walls than auricles to generate higher pressure to drive blood over long
distance into more elaborate circulation/to the lungs and to all body tissues;
- Walls of left ventricles are thicker than those of right ventricles to generate more pressure to pump
blood to longer distance in the systemic circulation/rest of the body;
- Longitudinal septum which separates the heart into two halves to prevent mixing of oxygenated and deoxygenated blood;
- Valves to prevent back flow of blood;
- Valves have strands of connecting tissue (chordas tendinae) to prevent them from being pushed
inside out when ventricles contract;
- Has coronary artery and coronary vein to supply myocardium with oxygen and nutrients; and remove waste products/carbon IV oxide and nitrogenous wastes;
- Fibrous layer of pericardium surrounds the heart to keep it in position; and prevent overdilation;
- Inner percadium secretes the pericardial fluid; which reduces friction between the two layers during contraction;
- outer pericardium surrounded by layer of fat which acts as shock absorber; protect it from
mechanical damage
- Sino Atrial Node (S.A.N) acts a pacemaker regulating rate of beating and excitation of heart;
- Heart located in the thoracic cavity where it is protected from any external mechanical damage;
- Atrio Ventricular node (A.V.N) which delays depolarization wave from Sino Atrial Node to ensure that auricles empty completely before the ventricles contract;
- Purkinje tissues to relay waves from A.V.N to ventricular myocardium; (20 mks)
Answer:Has valves to prevent backflow of blood