Question

Write notes on the working of the heart of the man with the help of a neat labeled diagram. Add a note on double circulation.

Answer 1

Hint:Circulation of fluids especially blood is the most important function of the heart. It is a muscular hollow organ that contracts and relaxes. It functions to pump and receive oxygenated and deoxygenated blood respectively. It consists of pulmonary and systemic circuits.

Complete answer:To understand the working of the heart we first need to understand the structure of the heart. The heart is a muscular hollow organ covered by double membranous tissue called the pericardium. The pericardium encloses pericardial fluid that lubricates the heart. The heart is divided into four chambers. Two of these chambers are called upper atria and two of them are lower ventricles.
The two of the atria are separated by an inter-atrial septum and the two ventricles are separated by an interventricular septum. The atrioventricular septum separates the atrium and ventricle of one side. The right atrium receives superior and inferior vena cavae. The right ventricle receives the pulmonary artery. The left atrium, on the other hand, consists of four pulmonary veins. The left ventricle is connected to the aorta. There are valves present in the heart that guard each chamber. The right atrium and the right ventricle are guarded by a tricuspid valve. The left atrium and the left ventricle are guarded by a bicuspid valve.

Now, let us understand the working of the heart.
Blood from the upper and lower body is poured in the right atrium by the superior vena cava and the inferior vena cava respectively. Also, blood from the heart muscle is received through the coronary sinus of the heart. The right atrium is the larger of the two atria and is made up of thin walls. The atrium is attached to the right ventricle by the right atrioventricular valve. This allows blood to flow into the ventricle from the atria. But this blood cannot go in the reverse direction.
From here, the right ventricle pumps the blood towards the lungs. Here, the blood will be reoxygenated. After purification, the reoxygenated blood is poured into the left atrium by the pulmonary veins. The left atrium has thicker walls than the right atrium and is smaller in size. The left atrioventricular valve opens into the left ventricle. It is also a one-way valve.
At last, the left ventricle transports the blood through the aorta to the whole body. Aorta is the largest artery of the body.
The heart is the major organ in the circulation of blood. The pumping of blood from the body to the heart forms the first circulation called systemic circulation. The second circulation occurs when blood is pumped from the heart to the lungs and again to the heart. Thus, the heart performs a double circulation. Double circulation is an efficient way of circulation. One route of the double circulation carries oxygenated blood and the other carries the deoxygenated blood.

Note:The majority of mammals including Humans perform double circulation as it provides an efficient way of circulation. On the other hand, fishes, birds, etc. perform single circulation. The heart is a very sensitive organ and thus prone to many diseases and disorders. Thus, scientists are currently working on making artificial 3-D hearts as a cure.