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Components of Blood and Its Function..

Plasma, in which the blood cells are suspended, including: Red blood cells (erythrocytes) - carry oxygen from the lungs to the rest of the body. White blood cells (leukocytes) - help fight infections and aid in the immune process. Types of white blood cells include: Lymphocytes. Monocytes. Eosinophils. Basophils. Neutrophils (granulocytes). Platelets (thrombocytes) - help in blood clotting. Nutrients. Chemical substances Proteins. Gases, including: Oxygen. Carbon dioxide. Nitrogen.

Liquid part of blood 55% of blood volume 90% water 100+ substances dissolved in plasma Blood plasma is a mixture of proteins, enzymes, nutrients, wastes, hormones, Metal ions (salts) and gases.

Function: transportation for all watersoluble substances

Function of the protein substances: The protein substances (albumin,globulins) are active in defence functions, but also in the binding of water Fibrinogen, which is a soluble precursor of a sticky protein called fibrin, which forms the framework of blood clot. Fibrin plays a key role in coagulation of blood, which is discussed later in this article under Platelets.

There are three major categories of plasma proteins

Nutrients Those absorbed by the digestive tract are transported in the blood plasma. These include glucose, amino acids, fats, cholesterol, phospholipids, vitamins and minerals. Gases Some oxygen and carbon dioxide are transported by plasma. Plasma also contains a substantial amount of dissolved nitrogen.

electrolytes (salts, sodium, potassium, calcium, chlorides). These complex mechanisms also maintain the blood within a slightly alkaline range (pH = 7.42).

White blood cells (WBCs) are also known as leukocytes.

Granule Lobed nuclei ! Number: They represent the largest share of the white blood count (approx. 60%) ! Size: approx. 10 m in diameter ! Function: They are able to devour micro-organisms (e.g. bacteria). They are therefore also called macrophages or phagocytes. ! Characteristics: They can also use amoeboid motion to leave the bloodstream actively and penetrate tissues. ! Place of origin: They are produced in the red bone marrow





contain very fine cytoplasmic granules Neutrophils are also called polymorphonuclear (PMN) Fuction : play roles in the destruction of bacteria and the release of chemicals that kill or inhibit the growth of bacteria.


have large granules and a prominent nucleus that is divided into two lobes Fuction : function in the destruction of allergens and inflammatory chemicals, and release enzymes that disable parasites.

Basophils have a pale nucleus that is usually hidden by granules. Function : secrete histamine which increases tissue blood flow via dilating the blood vessels, and also secrete heparin which is an anticoagulant that promotes mobility of other WBCs by preventing clotting.


Lack visible granules Nuclei spherical, oval or kidney-shaped


Lymphocytes Monocytes

Cytoplasm - stains pale blue; thin rim around nucleus Nucleus -spherical; stains dark purple Function - destroying cancer cells, cells infected by viruses, and foreign invading cells. In addition, they present antigens to activate other cells of the immune system. They also coordinate the actions of other immune cells, secrete antibodies and serve in immune memory. Place of origin: They are formed in the lymphoid organs (spleen and lymph nodes).

Cytoplasm -abundant; stains grayblue Nucleus -U or kidney shaped Function - differentiating into macrophages, which are
large phagocytic cells, and digest pathogens, dead neutrophils, and the debris of dead cells. Like lymphocytes, they also present antigens to activate other immune cells. Location of genesis: They are also produced in the red bone marrow.