Sickle-cell anaemia

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Sickle-cell disease is an inherited blood disorder in which the red blood cells change shape in a characteristic way.

Haemoglobin is a special protein in red blood cells that carries oxygen around the bloodstream. In sickle-cell disease, the haemoglobin is abnormal and this causes a change in the shape of the red blood cells.

A continuous supply of oxygen is essential for life. Oxygen is carried from the lungs to all parts of the body by the blood.In sickle-cell disease if the oxygen content in the haemoglobin is low, the haemoglobin sticks together to form long rods inside the red blood cells making these cells rigid and sickle shaped (hence the name). Red blood cells are normally a rounder shape, rather like a donut.

The sickled red cells:

Have a weaker structure and a much shorter life than the normal four months for red blood cells. This leads to Anaemia.Â·
Because of their shape, sickled cells clump together, especially in the smallest blood vessels, the blood becomes more viscous (sticky). The result is slowing of the flow, even greater loss of oxygen from the haemoglobin, further sickling and, in extreme cases, complete blockage of small blood vessels. Such blockage is always serious, as it deprives tissues of their oxygen, glucose fuel and other nutrients and leads to local death of tissue and severe pain.Â·
After going through a series of cycles of sickling and de-sickling during their passage around the circulation, red blood cells containing a high concentration of sickled haemoglobin finally become permanently sickled. This is the result of changes in the membrane of the red cell.