The Blood System Of Human Beings Essays
The blood circulatory system of human beings consists of the heat, blood vessels and blood tissue. Blood is circulating continuously around the body enclosed in blood vessels. This type of transport system is called a closed blood system.
1. Anatomy and Histology
1.1 The heart
1.1.1 Position if the heart
It is situated in the chest cavity behind the sternum just above the diaphragm.It is suspended in a space called mediastinum. The heart is found between the lungs and its apex slightly directed to the left. It is held in position by large blood vessels entering and leaving is at the top.
1.1.2 External structure of the heart.
The heart is a hollow muscular pumping organ about the size of a closed fist. It is enclosed by a tough double-walled fibrous sac called the pericardium. The space between pericardium is filled with pericardial fluid which prevents friction with the constant beating of the heart. At the apex, the outer layer of the pericardium is attached to the diaphragm. There are coronary arteries and veins on the surface of the heart
External structure of the heart
1.1.3 Internal structure of the heart
A human heart has four chambers. The two upper chambers are the right and left atria. The atria are small and have thin walls. Below the atria are the right and left ventricles. The ventricles are larger and have thick muscular walls. The muscular walls of these four chambers consist of cardiac muscular tissue. Internally the…