BLOOD
Blood is made of four
components:
Plasma is a pale
yellow sticky liquid. It makes up 55% of the blood’s volume. The components of
plasma are water 92%, dissolved protein 8%, glucose, amino acids, vitamins,
minerals, urea, uric acid, CO2, hormones, antibodies. Plasma carries
dissolved materials such as glucose, amino acids, minerals, vitamins, salts,
carbon dioxide, urea, and hormones. It also carries heat energy.
Red Blood
Cells, also called erythrocytes,
are tiny biconcave disc-shaped cells. They do not have a nucleus or
mitochondria. Their cytoplasm is rich in haemoglobin.
O2 binds to the iron in haemoglobin. Red blood cells are made in the
bone marrow. They survive for about four months. They are destroyed and
recycled by the liver and spleen. They are destroyed because they have to
constantly change shape to pass through narrow blood vessels. When they die the
haemoglobin is stored in the liver and used to make new blood cells in the bone
marrow. They are very small. There are about 5 million red blood cells in 1 cc.
of blood. The rest that is not stored is converted into bile pigments.
Red Blood
Cells transport oxygen. Haemoglobin has a base of iron. The iron joins
with oxygen in areas of high oxygen concentration (in the lungs and releases
oxygen in areas of low oxygen concentration in the body cells.
Anaemia is the lack
of haemoglobin or red blood cells. The symptoms of
anaemia are pale skin colour and a loss
of energy.
RED BLOOD CELL PLATELET WHITE BLOOD CELL
White Blood
Cells (leucocytes) are colourless cells and
possess a nucleus. They function in defending the body against pathogens. Some
‘feed’ on pathogens by phagocytosis. These
white blood cells are called phagocytes.
Others, the lymphocytes produce
antibodies, the specific defense proteins. They are made by the bone marrow and
lymphatic tissue.
A white blood cell
ingests a pathogen by phagocytosis.
TYPES OF WHITE BLOOD CELLS
Lymphocytes
Lymphocytes are made in the bone
marrow and then stored in various in various parts of the lymphatic system.
Their main function is to make
antibodies.
Monocytes
Monocytes are large cells that
digest bacteria and other particles. They are also called macrophages. They have kidney shaped nuclei.
Platelets, also called thrombocytes, are tiny fragments of
large bone marrow cells. They carry specialised blood clotting chemicals. The
clotting chemicals are released where blood and lymph vessels are injured. A
nucleus is not present in platelets.
These platelets are
grouping at the site of a wound.
View this
animation about red blood cells.
View this
animation about white blood cells.