Anatomy

Anatomy

Biology includes the study of the anatomy and physiology of living organisms. Anatomy is the study of structure and physiology is the study of function.

Because the structure of living organisms is complex, anatomy is organized by levels, from the smallest components of cells to the largest organs and their relationships to other organs. Gross anatomy is the study of the body's organs as seen with the naked eye during visual inspection and dissection. Cellular anatomy is the study of cells and their components, which require special instruments such as microscopes and special techniques for observation.

CELLS

       Often thought of as the smallest unit living organisms a cell is made up of many even smallest parts, each with its own function. Human cells vary in size, but too small to be seen with naked eye.

  Human cells have a membrane that holds the contents together. However, this membrane is not just a sac. It has receptors that identify the cell to other cells. The receptors also react to substances produced in the body and to drugs taken into the body, selectively allowing these substance or drugs to enter and leave the cell. Reactions that take place at receptors often alter and controls a cell's function.

 Within the cell membrane are two major compartments the cytoplasm and the nucleus. The cytoplasm contain structures that consume and transform energy and carry out the cells function; the nucleus contains the cells genetic material and the structure that control cell division and reproduction.

  The body is composed of many different types of cells, each with its own structure and function. Some such as white blood cells, more freely, unattached to other cells. Other; such as muscles cells; are firmly attached one to another. Some cells. such as skin cells, divide and reproduce quickly, nerve cells, on the other hand, don't reproduce at all. Some cells; especially glandular cells, have as their primary function the production of complex substances, such as a hormone or as enzyme. For example, cells in the breast produce milk, those in the pancreas produce insulin, those in the lining of the lungs produce mucus, and those in the mouth produce saliva. Other cells have primary function that are not related to the production of substances  for example cells in the muscles and heart cont red. Never cells conduct electrical impulse allowing communication between the central nervous system (brain and spinal cord) and the rest of the body .