Structure and Function of Human Heart
Structure of human heart - external features
The heart is a hollow organ. It is situated slightly towards left side in the middle of the thorasic (chest) cavity. It is made up of CARDIAC MUSCLE (you have studied the cardiac muscle in 9th class). Heart is conical in shape with apex (pointed portion) facing downwards and the broad base directed upwards. Generally, it is the size of the fist of the person. It is protected on all sides by rib cage and by vertebral column on the back side
Pericardium: - Heart is enclosed in a double layered, transparent,thin sac called PERICARDIUM. The space between the inner and outer layers is called PERICARDIAL SPACE. It is filled with a fluid, PERICARDIAL FLUID. Pericardium and the pericardial fluid protect the heart from physical shocks or blows.
Two deep grooves - one vertical and one horizontal - are visible on the heart from out side. These grooves indicate that the heart is internally divided into four chambers - Two upper chambers called AURICLES and two lower chambers called VENTRICLES. The vertical groove indicates the presence of right and left chambers.
Very large veins that bring blood to the heart are called VENA CAVAE or CAVAL VEINS. Very large arteries that carry blood away from the heart are called AORTAE (Aorta = Singular).
Blood Vessels that bring blood to heart:
There are three large veins that bring the blood to heart from all the body parts. The SUPERIOR VENA CAVA collects deoxygenated blood from the upper parts of the body (such as head and neck). The INFERIOR VENACAVA or POST CAVAL vein brings deoxygenated
Hainan heart - External features
Blood from lower parts of the body (such as abdomen, hands and legs). These caval veins open into the right auricle. The third vein is the PLTLMONARY VEIN which brings oxygenated blood from the lungs
And opens into the left auricle.
Veins bring deoxygenated blood from tissues to heart. However, pulmonary vein is an exception to this - it carries oxygenated Mood from the lungs to the heart. The right auricle receives deoxygenated
Mood while the left auricle receives oxygenated blood.
In addition to these major veins, a pair of veins called CORONARY VEINS brings deoxygenated blood from the walls of the heart. These also open into right auricle.
Blood vessels that carry blood away from heart:- Heart receives oxygenated blood from lungs and pumps It various organs in the body, through large aortae (large arteries) called SYSTEMIC AORTA (or systemic trunk) and pulmonary aorta (or pulmonary trunk). The systemic aorta arises from the left ventricle and carries blood to all the body organs except lungs. The PULMONARY AORTA originates in the right ventricle. Outside the heart, it divides into two branches - RIGHT AND LEFT PULMONARY ARTERIES which carry Mood to right and left lungs. Arteries carry oxygenated Mood to the tissues - the only exception is pulmonary artery which carriers deoxygenated blood to the lungs.
There is a pair of CORONARY ARTERIES. They are carrying oxygenated blood to the heart muscle. In some people, the coronary arteries get blocked with age. When ttos happens, muscle cells in the heart do not receive oxygenated blood and stop working. TMs is called heart attack and if not treated immunity the patient may die due to the failure of the heart muscle.