COMPONENTS OF BLOOD IN BRIEF

24th December, 2021 Prelims

Plasma

Plasma constitutes 55% of total blood volume.
Composed of 90% water, salts, lipids and hormones, it is especially rich in proteins (including its main protein albumin), immunoglobulins, clotting factors and fibrinogen.
Plasma performs several functions: transporting blood cells and nutrients; regulating the body’s water and mineral salts; irrigating tissues; providing a defence against infections; and coagulating blood.
Red blood cells, white blood cells and platelets are suspended in plasma.

White Blood Cells

There are between 6,000 and 8,000 white cells per cubic millimetre of blood.
White cells, slightly larger than red cells, are also called leukocytes.
They purify and protect the body from infections.
Once an infection is detected in any part of the body, the while cells move in to fight it.

Platelets

Platelets, or thrombocytes, are smaller than the red and white blood cells.
Platelets play a role in blood coagulation and wound healing.
When a blood vessel ruptures, platelets combine with fibrin, derived from fibrinogen, to form a clot.

Red Blood Cells

A drop of blood the size of a pinhead contains approximately 5 million red blood cells (erythrocytes).
They are small biconcave disks without a nucleus and get their red colour from an iron-containing protein called hemoglobin.
Red cells make up between 37% and 43% of blood volume in women and between 43% to 49% in men.
Red blood cells carry oxygen throughout the body.

Antibodies, also referred to as immunoglobulins, are glycoproteins naturally produced in response to invading foreign particles (antigens) such as microorganisms and viruses.
They play a critical role in the immune system’s defense against infection and disease.

IgG	It is the only antibody that can pass through the placenta, and IgG transferred from the mother's body protects a newborn until a week after birth. IgG widely distributed to the blood and tissue, and protects the body.
IgM	IgM has a key role in the initial immune system. It is distributed to the blood.
IgA	It is distributed to serum, nasal discharge, saliva, breast milk and bowel fluid.
IgD	IgD is present on the surface of B cells and plays a role in the induction of antibody production.
IgE	IgE is related to immunity reactions to parasites, and has recently become known as a key factor of allergies such as pollinosis.

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