Our body and its structure
The structure of the human body is very complex. Our body is made of innumerable cells. These cells are divided into a number of groups which are called tissues. Certain tissues form the external surface of the body, while others join other tissues. Some tissues go to form ‘muscles’ while others form ‘nerves’. An organ is formed by a group of tissues. These organs can be made strong and can be developed by giving proper exercise and movements to them.
As you are aware, there are nine main organ systems in our body. Their brief descriptions are given below:
(1) The Skeletal System: It provides the skeleton for the body. There are many bones in it, whose joints are inter connected with several connec ting tissues. Thus a man can direct the various movements of his body. The back-bone has a special place in the human skeleton. (It is also closely related to the stature of a man)
(2) The Muscular System:—Us function is to help in the performance of movements of the different parts of the human body such as head, neck, arms, trunk, legs etc. It performs the function of blood circulation and sends the food in the food pipe of the body. All the activities of our body are governed by this system.
(3) The Digestive System:—Its function is to digest the food which generates energy. (The undigested food is also passed out in the form of stool through this system.)
(4) The Breathing System:—To get energy from the food that is digested, oxygen is necessary. This system helps in the procurement of oxygen. It also helps our body to send out carbon dioxide gas from it.
(5) The Circulatory System:—This system is responsible for sending the energy procured from the nourishing elements of our food and the oxygen procured from the air, to all the parts of the body. All the cells of our body require these things, i.e., energy and oxygen. Its circulation takes place through blood. The blood, the blood vessels and the heart—all three combined go to form this system.
(6) The Excretory System:—Its main function is to send out the refuse and the useless matter out of our body. The kidneys, urester and urinary bladder go to form this system. (The urine is passed out through this system.) Other parts of the body also assist in sending out the waste matter e.g., perspiration from the skin and sending out carbon dioxide gas from the lungs.
(7) The Reproductive System:—The organs which go to form this system are different in men and women. The reproductive organ of the male consists of the penis and the testes, while reproductive organ of the female consists of ovaries, uterus and other parts.
(8) The Nervous System;— It exercises a check over the functions of the different parts of human body. The brain, spinal chord and the nerves go to form this system.
(9) The Endocrine System:—’Endocrine* means secreting internally. This system mainly consists of certain glands, which secrete fluids, which get directly mixed up in the blood. These secretions are called ‘hormones’ and the glands secreting them are also called ‘ductless glands’. The main important glands are, thyroid, adrenal, pituitary and the pancreas. Though there are several systems in our body, yet all of them function together. The thyroid gland is mainly connected with the development of the body and the stature of a person. We will discuss it in brief in the next step.