At the end of the lesson, you should be able to State the
functions of blood: Red blood cells haemoglobin which aids in
oxygen transport White blood cells phagocytosis, antibody formation
and tissue rejection Platelets fibrinogen to fibrin, causing
clotting Plasma transport of blood cells, ions, soluble food
substances, hormones, carbon dioxide, urea, vitamins, plasma
proteins 2
What is Blood? Blood3 types of cells present in thehuman blood
cell: red blood cells (erythrocytes) white blood cells (leukocytes)
plasma, 55% platelets (thrombocytes)Plasma is a liquid
consisting91% water which has blood cells, 45%inorganic ions,
nutrients,waste products, hormonesand soluble proteins dissolvedin
it. 3
Red Blood Cells Blood Formed in bone marrows of long bones.
Formed from nucleated cells called erythroblasts. Exposed to
maximum surface area for the exchange of oxygen and carbon dioxide.
95% of the protein in red blood cell is haemoglobin and 5% of the
protein are enzymes that allow the cell to survive for about 120
days. cytoplasm containing haemoglobin plasma membrane 4
Red Blood Cells Blood The binding of oxygen to haemoglobin is
reversible. In the lungs, where oxygen concentration is high,
oxygen combines with haemoglobin to form oxyhaemoglobin. When blood
arrives at cells where the oxygen concentration is low, it unloads
and becomes maroon haemoglobin once again. high oxygen
concentration Hb + 4O2 Hb(O2)4 (haemoglobin) low oxygen
concentration (oxyhaemoglobin) 5
Red Blood Cells Blood As red blood cells pass through tissues,
they pick up carbon dioxide. Most of the carbon dioxide combines
with water to form carbonic acid. CO2 + H2O H2CO3 carbonic acid The
carbonic acid then ionises to form hydrogen ions and hydrogen
carbonate ions. H2CO3 H+ + HCO 3 carbonic acid hydrogen hydrogen
ion carbonate ion About 70% of the ions leave the red blood cells
and remain in plasma. When the blood reaches the lungs, carbon
dioxide is released and diffuses out of the blood to enter the
alveoli. Carbon dioxide is then breathed out. 6
What is anaemia? Lower red blood cell count Caused by
deficiency in iron in diet leading to less haemoglobin being
producedSymptoms: Easily tired, looks pale, breathless Whos
vulnerable? Pregnant ladies, people who have lost large amounts of
blood
Why do people living in highaltitudes have rosy cheeks?
Concentration of oxygen in air is lower Absorb insufficient oxygen
for respiration Acclimatisation Body produces more red blood cells
increase amount of haemoglobin per unit volume of blood Hence more
oxygen can be transported to cells
Blood group Red blood cells carry special protein called
antigens on their cell surfaces. Blood plasma contains antibodies.
Blood groups are classified according to the antibodies and
antigens present in their blood. There are four groups of blood,
named A, B, AB and O. Each group is named after the antigen
present. 9