Functions of the Blood

Our blood can be described as our life force, making sure our cells have all the essential supplies they need and keeping micro-organisms at bay.
The blood has several essential functions which are important for the body to survive. These functions can be divided into two main areas:
■ transportation
■ protection.


The erythrocytes transport oxygen attached to haemoglobin from the
lungs to the body’s cells and return carbon dioxide from the cells to the
lungs for elimination. Hormones and enzymes are transported from
their cells of production to their target organs and tissues.

The blood supplies nourishment to the cells. Nutrients are absorbed
from the small intestine into the bloodstream and are transported to
where they are needed.

The circulation removes waste products from the cells and surrounding
tissues. These waste materials are transported to liver to be prepared
for removal and to the kidneys for excretion.

White blood cells defend the body against the invasion of micro-organisms and their toxins. They achieve this through:
■ the phagocytic action of neutrophils and monocytes
■ the presence of antibodies and antitoxins.

Blood clotting prevents the loss of any body fluid and blood cells when
the tissues are injured.

The blood helps to maintain the body’s temperature. Chemical activity in
the cells and tissues produces heat. This heat makes the blood warm as
it circulates. If the body produces too much heat the blood vessels near
the surface of the body dilate and heat is lost by radiation, conduction,
convection and the evaporation of sweat. If the external temperature is
cold, the superficial blood vessels constrict to prevent heat loss.