(a) Describe the process of osmo regulation in (I) a named unicellular organism (ii) man
(b) Describe how the mammalian skin can react to regulate the body temperature in a hot room.
(a)(i) The process of osmoregulation in a named unicellular organism, e.g. Paramecium /Amoeba is as follows: Contractile vacuole carries osmoregulation in paramecium. The cell content of paramecium is hypertonic to the external medium. Therefore water enters, by osmosis into the cytoplasm and later into the contractile vacuole. To prevent the cell from being over turgid and bursting, the contractile vacuole discharges its content from time to time, thereby maintaining water balance within the organism.
(ii) The process of osmoregulation in man begins with the kidney. The kidneys carry out osmoregulation in
man, when the osmotic concentration of blood is higher than that of the cell content, by means of sugar/ Nucleus mineral salts/amino Acids/other plasma solutes. The kidneys extract these substances from the blood/ body cells and absorb more water. When these substances are present in small amounts in the blood there is higher osmotic pressure in body cells, thus decreasing osmotic concentration of the blood. The kidney extracts more water than usual by the action of ADH/hormones and more concentrated urine is produced, thus keeping the osmotic concentrations of blood and cell fairly constant/avoiding any damage. Water can also be lost through sweating and breathing out moist air.
(b) The mammalian skin can react to regulate the body temperature in a hot room. When there is excess heat in the body, blood flow in the dermal capillaries is stimulated and the blood vessels under the skin epidermic dilates whereby more blood is brought to the surface or the sweat picks up the latent heat of vaporization from the skin, cooling the skin down. Heat is also lost by radiation which allows air to flow through the follicles and through convention. The hair lies inclined / flat.
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