outline of anatomy and physiology L

outline of anatomy and physiology
Let's speak about human anatomy and physiology , which are the study , respectively , of the normal structure and functioning of the body . Just as houses are built of individual bricks , so is the body made up of millions of microscopic individual units called cells . Each cell has a job to do and must be supplied with fuel and oxygen before it can do it . In this respect the body is not different from any other working engine or machine . All engines,machines and body cells are alike in requiring oxygen to burn their fuel and thereby produce the energy needed to perform their functions .
The fuel needed by the body comes from our food , while oxygen is present in the air we breathe . Fuel and oxygen are conveyed in the blood to all parts of the body by the heart and circulation .
The food we eat is turned into usable fuel by a process known as digestion . The digestive system contains the stomach and intestines .
Oxygen is obtained from the air we breathe . The process by which it enters the blood to reach the body cells is called respiration . The respiratory system consists of the air passages and lungs .
Overall control and coordination of body functions is effected by the nervous system , which consist of the brain and nerves . The brain may be likened to a computerized telephone exchange with the nerves serving as telephone lines .
There are many different types of cell in the body , depending on their particular function,but they all contain a central nucleus and are bounded by a cell wall . The nucleus is responsible for growth by cell division,and contains chromosomes and genes which transmit the hereditary factors , which make every person a unique individual . The cell wall is sufficiently thin to allow oxygen and nutrients from the blood to enter the cell and waste products to leave .