TOPIC 1.CLASSIFICATION KINGDOM FUNGI
Red blood cells are formed in the
bone marrow. Their lifespan is about 120 days. The liver and the spleen destroy
old red blood cells and release haemoglobin for the formation of new
cells.
Haemoglobin is the red pigment in
erythrocytes. It has a high affinity for oxygen.
The function of red blood cells is
to transport oxygen and carbon dioxide. The adaptation red blood cells that
make them suited forthis function are the presence of haemoglobin, their large
numbers, biconcave shape and the lack of nucleus which increases the total
surface area of gaseous exchange.
Transport of
oxygen
In the lungs (where there is a high
concentration of oxygen), haemoglobin combines with oxygen to form
oxyhaemoglobin. This is an unstable compound which releases oxygen when it
reaches tissues that have a low concentration of oxygen. The formation of
oxyhaemoglobin and release oxygen and haemoglobin can be shown using the
following equation.
Haemoglobin + oxygen =
Oxyhaemoglobin
Oxygen diffuses out of the red blood
cells, through the capillary walls to the tissues.
Transport of carbon dioxide
In the red blood cells, carbon
dioxide combines with haemoglobin to form carbominohaemoglobin. This compound
is transported to the lungs where carbon dioxide is released and expelled from
body.
White blood cells
Another name
for the white blood cells is
leucocytes. These cells have irregular shapes; milliliter of blood has
approximately 5000 to 10 white blood cells
