The Human Body System

 Every part of the human body is made up of minute parts, which are called cells, and intercellular substance which is produced by the cell. Thus, the smallest functional unit of a living being is called a cell. Each cell is so small that it can be seen only through a microscope. Each cell has three main parts. They are: the cell wall which surrounds and protects the cell; the protoplasm, a grayish jelly-like material, which is really the body of the cell; and the nucleus which is the life centre inside the body of the cell.

     

 The Human Body System Each cell lives its own life. It grows and multiplies by dividing itself into two halves. The cells after the division from the group of cells and the group of cells having similar characteristics and functions is called a tissue. The body is made up of five types of tissues. Each serves a different purpose. Each reacts to different stimuli, e.g. the group of nerves cells from the nerves tissue which works as the nerves system. The tissues in their turn construct internal and external organs related with special functions. For convenience, the organs may be grouped to form the system.

Thus, a group of organs having a specific function is called a system. Each system contributes to one or more of the vital functions of the body. For example, the digestive system consists of food pipe (oesophagus), stomach, intestine, etc. Thus, the system of organs related to chewing, swallowing, digesting and absorbing the food and finally discarding the unwanted food is called the digestive system. In the same way, the nose, trachea (wind pipe) and lungs form a group called the respiratory system which provides the route by which the supply of oxygen present in the atmospheric air gains entry into the body and provides the route of excretion of carbon dioxide. Besides this, there are some other systems for different functions of the body.

      In fact, the body works with the help of individual cells, tissues, organs and various systems. Altogether, there are nine systems in the human body. They are:

i)       The skeletal system                                        ii)       The muscular system

iii)     The digestive system                                      iv)      The respiratory system

v)      The circulatory system                                   vi)       The urinary system

vii)    The glandular system                                     viii)     The nervous system, and

ix)     The reproductive system.

The circulatory system: Our body is made up of millions of tiny cells. Each of these cells must have food and oxygen to live. The required nutrients and oxygen are supplied through the blood circulation. Blood supplies all the organs of the body with nutrients and oxygen, removes waste products and performs other vital functions. The continues movement of blood through an organism to supply the nutrients and oxygen and to remove waste products is called blood circulation. Energy is produced by the chemical process of uniting nutrients and oxygen; this process is called oxidation. Our blood is driven through the pumping action of our heart. The blood circulates through the body by way of arteries, veins and capillaries. It takes about twenty-three seconds for the blood to flow from the heart

through our body and back to our heart again.