Question

Why is blood circulation in the human heart called double circulation?

Answer 1

Heart is a muscular organ of the body. Heart falls in the circulatory system as its function is to pump blood throughout the body. Function of the heart includes pumping oxygenated blood to the other body parts. Pumping hormones and other vital substances to different body parts also receiving deoxygenated blood and carrying metabolic waste products from the body.

Complete answer:
The walls of the heart are made up of three layers: Epicardium, Myocardium and Endocardium. The human heart is placed in the middle Mediastinum. The upper part of the heart is the attachment point of several large blood vessels: the Vena cava aorta and Pulmonary trunk. The lower tip of the heart lies to the left side of the sternum between the junction of fourth and fifth ribs near the costal cartilages. Heart’s two upper atria which are receiving chambers and two lower ventricles which are discharging chambers.
The circulation of the heart is called double circulation in the human heart as the blood completes one cycle of the body through the heart twice. Blood passes once through the right half and another from the left half. While passing from the right half the blood passes in the form of deoxygenated blood and from the left half it passes oxygenated blood. This can be seen in the following diagram:

The Sino-atrial node is a nodal tissue which is present in the upper part of the right auricle. It generates nerve impulses which are responsible for contraction of the heart.

Note:
Purkinje’s fibers are specialized conducting fibers composed of electrically excited cells composed of electrically excited cells. They are myofibrils with mitochondria which conducts cardiac action potentials more quickly and efficiently than any other cells in the heart. The advantages of double circulation are it contains two loops and due to blood flow at a high pressure, it can flow smoothly to the rest of the body.