The heart is a muscular organ about the size of a closed fist that functions as the body’scirculatory pump. It takes in deoxygenated blood through the veins and delivers it to the lungsfor oxygenation before pumping it into the various arteries. The heart is located in the thoraciccavity between the two lungs.The heart is adapted to carry out its functions by having the following features:
1. The heart has a large number of mitochondria enabling continuous supply of energy to theheart and numerous myoglobins (oxygen storing pigment).
2. The presence of the cardiac muscles enables the heart to beat rhythmically.
3. The pericardium which surrounds and protects the heart from physical damage.
4. Pericardial fluid which prevents friction when the heart beats.
5. The outer layer of the pericardium attaches to the breastbone and other structures in the chestcavity and thus helps to hold the heart in place.
6.Bicuspid and tricuspid valves between atria and ventricles which prevent the backflow ofblood.
7. Septum which prevents the mixing of deoxygenated blood in the right and oxygenated blood in the left chambers of the heart.
8. The left ventricle has thick muscular wall to pump blood at a higher pressure to the distantbody tissues,
9. The heart is supplied with the nerves which control the rate of heartbeat depending on thebody requirements.