Components of blood and their functions.

Structure and Function of Blood

Composition of Blood

 Their are 4 fundamental components of blood that are crucial for maintainig general life balance,,

These are:

  • The mammalian blood is made up of a fluid medium called plasma with substances dissolved in it.

  • Cellular components suspended in plasma include;
  • erythrocytes (red blood cells),
  • leucocytes (white blood cells)
  • thrombocytes (platelets)
  • blood proteins.


  • Plasma

  • This is a pale yellow fluid consisting of 90% water.
  • There are dissolved substances which include;
  • glucose, amino acids, lipids, salts,
  • hormones, urea, fibrinogen, albumen,
  • antibodies, some enzymes suspended cells.
  • Serum is blood from which fibrinogen and cells have been removed.

    The functions of plasma include:

  • Transport of red blood cells which carry oxygen.
  • Transport dissolved food substances round the body.
  • Transport metabolic wastes like nitrogenous wastes and carbon (IV) oxide in solution about 85% of the carbon (IV) oxide is carried in form of hydrogen carbonates.
  • Transport hormones from sites of production to target organs.
  • Regulation of pH of body fluids.
  • Distributes heat round the body hence regulate body temperature.

    Erythrocytes (Red Blood Cells)

  • In humans these cells are circular biconcave discs without nuclei.
  • Absence of nucleus leaves room for more haemoglobin to be packed in the cell to enable it to carry more oxygen.
  • Haemoglobin contained in red blood cells is responsible for the transport of oxygen.
  • Haemoglobin + Oxygen =oxyhaemoglobin
  • (Hb) + (4O2) __ (HbOg)
  • Oxygen is carried in form of oxyhaemoglobin.
  • Haemoglobin readily picks up oxygen in the lungs where concentration of oxygen is high.
  • In the tissues, the oxyhaemoglobin breaks down (dissociates) easily into haemoglobin and oxygen.
  • Oxygen diffuses out of the red blood cells into the tissues.
  • Haemoglobin is then free to pick up more oxygen molecules.
  • The biconcave shape increases their surface area over which gaseous exchange takes place.
  • Due to their ability, they are able to change their shape to enable themselves squeeze inside the narrow capillaries.
  • There are about five million red blood cells per cu bic millimetre of blood.
  • They are made in the bone marrow of the short bones like sternum, ribs and vertebrae.
  • In the embryo they are made in the liver and spleen.
  • Erythrocytes have a life span of about three to four months after which they are destroyed in the liver and spleen.
  • Also in the red blood cells is carbonic anhydrase which assists in the transport of carbon (IV) oxide.

    Leucocytes (White Blood Cells)

  • These white blood cells have a nucleus. They are divided into two:

    - Granulocytes (also phagocytes or polymorphs) - Agranulocytes .

  • White blood cells defend the body against disease.
  • Neutrophils form 70% of the granulocytes.
  • Others are eosinophils and basophils.
  • About 24% agronulocytes are called lymphocytes, while 4% agranulocytes are monocytes.
  • The leucocytes are capable of amoebic movement.
  • They squeeze between the cells of the capillary wall to enter the intercellular spaces.
  • They engulf and digest disease causing organisms (pathogens) by phagocytosis.
  • Some white blood cells may die in the process of phagocytosis.
  • The dead phagocytes, dead organisms and damaged tissues form pus.
  • Lymphocytes produce antibodies which inactivate antigens.
  • platelets
  • platelets plays a fundamental part in clothing of blood.
  • Comments

    Popular posts from this blog

    "iPhone 16: Revolutionizing Tech or Just Another Upgrade? Pros and Cons Unveiled''

    High demand skills to learn after high school

    Difference between diabetes insipidus and diabetes mellitus.