Transport in Human

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

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