Parameters ( 參數 ) of internal environment: body temperature composition of blood. blood pressure

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Alisha Hunter
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Class: Name: ( ) Date: 18 Homeostasis 18.1 The concept of homeostasis (Book 2, p. 18-3) A What is homeostasis? (Book 2, p. 18-3) The external environment is continually changing.

External environment Homeostasis Parameters ( 參數 ) of internal environment: body temperature composition of blood relatively constant composition of tissue fluid continually changing body cells

1 Class: Name: ( ) Date: 18 Homeostasis 18.1 The concept of homeostasis (Book 2, p. 18-3) A What is homeostasis? (Book 2, p. 18-3) The external environment is continually changing. It is important to keep the internal environment of our body (1) for cells to function properly. Maintenance of a stable or relatively constant (2) environment is called (3) ( 體內平衡 ). External environment Homeostasis Parameters ( 參數 ) of internal environment: body temperature composition of blood relatively constant composition of tissue fluid continually changing body cells bathed in tissue fluid blood pressure capillary blood Keeping the internal environment relatively constant is important for survival B Major parameters of the internal environment (Book 2, p. 18-4) 1 Body temperature A stable body temperature is essential for (4) to function properly. In humans, the (5) is involved in keeping the body temperature at C. (Second Edition)

<35 C severe shivering ( 顫抖 ), numbness ( 麻痺 ) of skin >37.5 C fever 36.

2 <35 C severe shivering ( 顫抖 ), numbness ( 麻痺 ) of skin >37.5 C fever C normal body temperature >41 C fainting, confusion Note: Death may result if body temperature drops below 28 C or rises above 43 C. What happens to our body if the body temperature falls outside the normal range 2 Water content in blood The water content in blood affects the (6) of the tissue fluid, which in turn affects that of the cell. A stable water potential in the cells is important so that cells can carry (7) activities properly. The water content in blood is regulated by the (8) ( 腎 ) of the (9) system ( 泌尿系統 ). posterior vena cava aorta kidneys ureters urinary bladder urethra The human urinary system (Second Edition)

3 3 Gas content in blood The (10) content in blood has to be kept stable to provide sufficient oxygen to cells for respiration. The (11) content in blood has to be kept stable to maintain a stable ph in blood. Their contents in blood are regulated by controlling (12) and (13). Both the (14) system and the (15) system are involved in the regulation of gas content in blood. 4 Glucose level in blood The glucose level in blood has to be kept stable to provide sufficient glucose to cells for (16). As glucose is (17) in water, keeping a stable blood glucose level is also important for keeping a stable (18) in the tissue fluid. The blood glucose level is mainly regulated by the (19) and the (20) Mechanism of homeostasis (Book 2, p. 18-6) A The principle of mechanism (Book 2, p. 18-6) Homeostasis is usually brought about by (1) ( 負反饋機制 ). An everyday example of mechanism is the operation of the air conditioner. S RT > S Thermostat ( 恆溫器 ) detects an RT remains fairly constant (2) in RT. Cooling system is turned (3), cooling the air back to S. RT < S Key: RT = room temperature S = set temperature Thermostat detects a (4) in RT. Cooling system is turned (5), allowing RT to increase to S. (Second Edition)

4 In our body, a mechanism involves three components: Component Description (6) Detects (7) in the level of the parameter (8) centre (11) Processes information and coordinates the activities of different organs Usually part of the (9) system or the (10) system Receives instructions from the control centre and produces a response that has an (12) (negative) effect to the original change level of parameter higher than normal receptor control centre effector response to (13) the level normal level of parameter response to level of parameter lower than normal receptor control centre effector (14) the level Negative feedback mechanism B Regulation of blood glucose level (Book 2, p. 18-7) The (15) contains chemoreceptors that detect changes in blood glucose level. It is also an (16) gland that produces hormones involved in regulation of blood glucose level. (17) cells and (18) cells are effectors in regulation of blood glucose level. (Second Edition)

5 Hormones involved in regulation of blood glucose level: Hormone Action Overall effect on blood glucose level Stimulates (20) cells to convert (19) ( 胰島素 ) excess glucose to (21), which is then stored in the liver and muscles Stimulates (22) cells to take in more glucose. The glucose will then be broken (23) (Increase / Decrease) down into carbon dioxide and water in the cells (24) ( 胰高血糖素 ) Stimulates (25) cells to convert stored glycogen to glucose (26) (Increase / Decrease) blood glucose level higher than normal pancreas produces more (27) and less (28) liver cells and body cells (29) blood glucose level by: 1 converting excess glucose to glycogen in liver cells 2 increasing glucose uptake by body cells after a meal normal blood glucose level during fasting or after exercise blood glucose level lower than normal pancreas produces more (30) and less (31) liver cells (32) blood glucose level by converting stored glycogen to glucose Regulation of blood glucose level (Second Edition)

6 What will happen if we fail to regulate blood glucose level? (Book 2, p. 18-9) If the pancreas produces too little or no insulin, or if body cells do not respond to insulin, (33) ( 糖尿病 ) occurs. The blood glucose level of diabetics ( 糖尿病患者 ) becomes very high after a meal. The body fails to reabsorb all the glucose, resulting in the appearance of glucose in (34). Body cells will lose (35) to the blood by osmosis, leading to an increase in (36) production and excessive (37). Changes in blood glucose level of a healthy person and a diabetic after glucose intake: A 210 blood glucose level (mg/100 cm 3 ) C B normal level glucose intake time (h) Curve Changes in blood glucose level after glucose intake Healthy person (38) The blood glucose level (39) and then returns to (40) within a short time. The blood glucose level remains (42). Diabetic (41) The level then (43) gradually due to the loss of glucose in urine. (44) After receiving injection of (45), the blood glucose level is brought back to normal. (Second Edition)

7 Answers Ch 18 Homeostasis stable 2 internal 3 homeostasis 4 enzymes 5 skin 6 water potential 7 metabolic 8 kidneys 9 urinary 10 oxygen 11 carbon dioxide 12 breathing 13 heart beat 14 breathing / circulatory 15 circulatory / breathing 16 respiration 17 soluble 18 water potential 19 liver / pancreas 20 pancreas / liver mechanism 2 increase 3 on 4 decrease 5 off 6 Receptor 7 changes 8 Control 9 nervous / endocrine 10 nervous / endocrine 11 Effector 12 opposite 13 decrease 14 increase 15 pancreas 16 endocrine 17 Liver / Body 18 body / liver 19 Insulin 20 liver 21 glycogen 22 body 23 Decrease 24 Glucagon 25 liver 26 Increase 27 insulin 28 glucagon 29 decrease 30 glucagon 31 insulin 32 increase 33 diabetes mellitus 34 urine 35 water 36 urine 37 thirst 38 C 39 rises 40 normal 41 A 42 high 43 decreases 44 B 45 insulin (Second Edition)

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