Blood structure and function in the body.

Blood

Blood can be defined as: the circulating fluid () and suspended , such as ,  and  in the  of humans and other . This essay will mention about structure of the blood and the functions of the blood.

Structure of blood has four major parts these are: plasma, red blood cells, white blood cells, and platelets. Plasma is mainly made up from water; nearly %90-%92 is water. This is a straw coloured fluid. Plasma contains dissolved substances including electrolytes for example: sodium, chlorine and potassium. Albumin, globulin and fibrinogen are the protein of blood plasma. Hormones are also in the blood plasma. Red blood cells also named as erythrocytes. Red blood cells sometimes may be immature and they do have nucleus but in general, the mature ones do not have any nucleus. This gives them ability to carry more oxygen. They only exist for 120 days in body and there are approximately 4.5 - 5.8 million erythrocytes per micro-litre of healthy blood. This quantity depends on gender and age. White blood cells also named as leucocytes. There are different types of leucocytes. These can be defined as; granular and agranural. Depending on their types, they sometimes exist for few hours to few days but sometimes they can exist for many years. Platelets also called as trombocytes. These are granular and disk-shaped cell fragments. They do not have nucleus and they have longevity of approximately 5-9 days.