1 Think about 18 1 The concept of
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Think about… 18. 1 The concept of homeostasis 18. 2 Regulation of blood glucose level Recall ‘Think about…’ Summary concept map 2
18. 1 The concept of homeostasis Do you know what homeostasis is? 3
18. 1 The concept of homeostasis What is homeostasis? • ability of the body to maintain a stable internal environment - composition of blood and tissue fluid - body temperature - blood pressure • important for body to function properly 4
18. 1 The concept of homeostasis What is homeostasis? For example: Our body is exposed to changes in the external environment, e. g. air temperature homeostasis 5
18. 1 The concept of homeostasis What is homeostasis? blood For example: The condition of blood and tissue fluid is kept constant for proper functions of cells capillary body cell bathed in tissue fluid 6
18. 1 The concept of homeostasis Parameters of the internal environment to be kept stable What parameters must be kept constant in our body? 7
18. 1 The concept of homeostasis 1 Water content in blood water content affects water potential in blood of tissue fluid 8
18. 1 The concept of homeostasis 1 Water content in blood enter the cells or leave the cells If water potential of tissue fluid is different from that of the cells, water will … 9
18. 1 The concept of homeostasis 1 Water content in blood If too much water is gained … 10
18. 1 The concept of homeostasis 1 Water content in blood If too much water is lost … 11
18. 1 The concept of homeostasis 1 Water content in blood If too much waterfunction is lost … cells cannot properly and may even die 12
18. 1 The concept of homeostasis 1 Water content in blood • regulated by kidneys (腎) ureters kidneys urinary bladder urethra mammalian urinary system 13
18. 1 The concept of homeostasis 2 Glucose level in blood • for respiration in cells energy + CO 2 + water glucose + O 2 - level in blood is kept steady to ensure a sufficient supply - as it is water soluble, any change in level affects water potential of the tissue fluid 14
18. 1 The concept of homeostasis 2 Glucose level in blood In humans, • normal range is 90– 100 mg/cm 3 • maintained by liver pancreas 15
18. 1 The concept of homeostasis 3 Gas content in blood • in respiration glucose + O 2 energy + CO 2 + water content in blood is kept steady to ensure a sufficient supply 16
18. 1 The concept of homeostasis 3 Gas content in blood • in respiration glucose + O 2 energy + CO 2 + water dissolves in blood too much / too little affects p. H of blood and tissue fluid affects enzyme activity 17
18. 1 The concept of homeostasis 3 Gas content in blood • regulated by breathing heartbeat 18
18. 1 The concept of homeostasis 4 Body temperature • normal range is 36. 5– 37 C • kept steady for enzymes to function properly • regulated by skin 19
18. 1 The concept of homeostasis 4 Body temperature What are the effects of failing to regulate body temperature? 20
18. 1 The concept of homeostasis 4 Body temperature C 44 42 >37. 5 death CNS breakdown fever 33 loss of consciousness 28 muscle failure 21
18. 1 The concept of homeostasis Mechanism of homeostasis • by negative feedback mechanism (負反饋機制) 22
18. 1 The concept of homeostasis Negative feedback mechanism Set point When the room temperature (RT) is higher than the set temperature (S) … 23
18. 1 The concept of homeostasis Negative feedback mechanism RT > S thermostat turns compressor on, cooling the air back to set temperature 24
18. 1 The concept of homeostasis Negative feedback mechanism When the room temperature (RT) is lower than the set temperature (S) … 25
18. 1 The concept of homeostasis Negative feedback mechanism thermostat turns compressor off, allowing room temperature to increase RT < S 26
18. 1 The concept of homeostasis Negative feedback mechanism Three components: Receptor Detects changes in the level Control centre of the parameter Processes information from receptor and coordinates different organs nervous system or endocrine system 27
18. 1 The concept of homeostasis Negative feedback mechanism When level of parameter is higher than normal, receptor normal level of parameter control centre effector response to decrease the level back to normal 28
18. 1 The concept of homeostasis Negative feedback mechanism response to increase the level back to normal receptor control centre effector When level of parameter is lower than normal, 29
Why is called “negative” feedback system? ? ? 30
Why is called “negative” feedback system? ? ? The corrective action is always opposing to the deviation. 31
18. 1 The concept of homeostasis Negative feedback mechanism What are the Components in a feedback system? ? ? RT > S thermostat turns compressor on, cooling the air back to set temperature 32
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18. 1 The concept of homeostasis Negative feedback mechanism What are the Components in a feedback system? ? ? Receptor Detects changes in the level of the parameter Control Processes information from centre receptor and coordinates different organs Effector Produces a response opposite to the original change 34
18. 1 1 The concept of homeostasis Homeostasis is the ability of the body to maintain a stable internal environment. 35
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18. 2 Regulation of blood glucose level 37
We are addicted to sugar 38
Importance of blood sugar • Hyperglycemia: blood glucose level goes above 7. 0 mmol/L. –The levels are increased in diabetes mellitus. • Hypoglycemia: blood glucose level falls below 3. 0 mmol/L, this would lead to a loss of consciousness (coma). 39
Importance of blood sugar regulation Health risks of Hyperglycaemia 40
18. 2 Regulation of blood glucose level Roles of liver and pancreas • they work together • pancreas secretes hormones insulin glucagon both act on liver but with opposite effects 41
18. 2 Regulation of blood glucose level Roles of liver and pancreas Insulin decreases blood glucose level excess glucose liver cells glycogen stored in muscles liver Body cells take in more glucose body cells glucose CO 2 + water 42
18. 2 Regulation of blood glucose level Roles of liver and pancreas Glucagon increases blood glucose level liver cells stored glycogen glucose Let’s see how blood glucose level is regulated by negative feedback mechanism. 43
18. 2 Regulation of blood glucose level Roles of liver and pancreas higher than normal pancreas secretes more insulin and less glucagon liver cells and body cells normal blood glucose level 44
18. 2 Regulation of blood glucose level Roles of liver and pancreas higher than normal pancreas secretes more insulin and less glucagon liver cells and body cells Decrease level by: 1 converting more glucose to glycogen in liver cells 2 increasing glucose uptake and oxidation by body cells 45
18. 2 Regulation of blood glucose level Roles of liver and pancreas Increase level by: converting stored glycogen to glucose lower than normal pancreas secretes more glucagon and less insulin liver cells 46
18. 2 Regulation of blood glucose level Failing to regulate blood glucose level What will happen if blood glucose level is too high? 47
18. 2 Regulation of blood glucose level Failing to regulate blood glucose level too high water leaves cells by osmosis normal metabolism affected glucose passes out in urine diabetes mellitus 48
18. 2 Regulation of blood glucose level Failing to regulate blood glucose level it results when the pancreas fails to produce or does not produce enough insulin diabetes mellitus 49
18. 2 Regulation of blood glucose level (mg/100 cm 3) 200 healthy person 150 level returns to normal within a short time 100 normal 1 2 glucose intake 3 time (hrs) 50
18. 2 Regulation of blood glucose level (mg/100 cm 3) 200 diabetic 150 level remains high and then drops very slowly 100 normal 1 2 glucose intake 3 time (hrs) 51
18. 2 Regulation of blood glucose level (mg/100 cm 3) 200 diabetic 150 the drop is due to the loss of glucose in urine 100 normal 1 2 glucose intake 3 time (hrs) 52
18. 2 Regulation of blood glucose level diabetic glucose level in urine 1 glucose intake 2 time 3 (hrs) 53
Common symptoms of diabetes mellitus: • • Frequent urination. Excessive thirst. Extreme hunger. Unexplained weight loss. • • Sudden vision changes. Tingling or numbness in the hands or feet. Feeling very tired much of the time. Very dry skin……. . 54
Common symptoms of diabetes mellitus (type I): 55
18. 2 Regulation of blood glucose level Diabetics need insulin injections 56
18. 2 Regulation of blood glucose level 3) (mg/100 cminjection of insulin 200 150 diabetic level drops quickly 100 normal 1 2 glucose intake 3 time (hrs) 57
18. 2 Regulation of blood glucose level Failing to regulate blood glucose level How about if the blood glucose level is too low? 58
18. 2 Regulation of blood glucose level Failing to regulate blood glucose level too low insufficient supply of glucose for respiration neurones cannot function person becomes unconscious 59
Pancreatic hormones regulate blood glucose levels – The pancreas secretes two hormones • Insulin – Signals cells to use and store glucose • Glucagon – Signals cells to release stored glucose into the blood 60
61 http: //www. sunyniagara. cc. ny. us/val/pancreas 2. jpg
The islets are composed of three cell types: alpha cells, beta cells, and delta cells. These cells cannot be readily distinguished without special stains. The insulin producing cells are called cells and make up about 70% of the islet cells. The glucagon producing cells are called cells and make up about 15 20% of the islet cells. 62 http: //www. cytochemistry. net/microanatomy/Endocrines/pancreas 2. jpg
SECRETORY ROLE CELL CHARACTERISTICS cells of islets of Langerhans Glucagon 15 - 20% of the islet cells; generally more peripherally located in the islet; more uniform in size; cytoplasm appears to be more densely packed than the cells of islets of Langerhans Insulin 70% of the islet cells; generally more centrally located in the islet Acinus cells Digestive enzymes Usually oriented in a circular pattern 63
Glucose balance Body cells Insulin take up more glucose Beta cells of pancreas stimulated to release insulin into the blood Liver takes up glucose and stores it as glycogen High blood glucose level Blood glucose level declines to a set point; stimulus for insulin release diminishes Stimulus: Rising blood glucose level (e. g. , after eating a carbohydrate-rich meal) Homeostasis: Normal blood glucose level (about 90 mg/100 m. L) Blood glucose level rises to set point; stimulus for glucagon release diminishes Liver breaks down glycogen and releases glucose to the blood Stimulus: Declining blood glucose level (e. g. , after skipping a meal) Alpha cells of pancreas stimulated to release glucagon into the blood Glucagon 64
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– Diabetes can be detected • By a test called a glucose tolerance test Blood glucose (mg/100 m. L) 400 350 300 Diabetic 250 200 150 Normal 100 50 0 0 1 2 3 Hours after glucose ingestion 4 5 68
Diabetes – an endocrine disorder – Diabetes mellitus • Results from a lack of insulin or a failure of cells to respond to it (absolute or relative inadequacy) – 2 types of diabetes • Type I (insulin-dependent) – Autoimmune disease – Beta cells destroyed, no insulin made • Type II – Body cells fail to respond to insulin 69
Diabetes: Type I and Type II Type I - autoimmune disorder (destroys ability to produce insulin) Type II - due to aging, lifestyle, heredity and other lifestyle (diet) factors decreased responsiveness by cells of target organs to insulin 70
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Complications related to Diabetes 75
People with diabetes mellitus (糖尿病) need to check blood glucose level and 76
People with diabetes mellitus (糖尿病) need to receive insulin injections several times a day… 77
This greatly affects our daily activities. 78
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A new device consists of a glucose sensor and an insulin pump 80
The sensor checks the blood glucose level 81
A suitable amount of insulin is released automatically into the body 82
18. 2 Regulation of blood glucose level more insulin and less secreted glucagon 1 more glucose high blood is converted to blood glucose glycogen in liver level falls 2 more glucose is oxidized by body cells 1 normal blood glucose level 83
18. 2 1 Regulation of blood glucose level normal blood glucose level low blood glucose stored glycogen is converted to level glucose in liver more glucagon and less insulin secreted blood glucose level rises 84
18. 2 Regulation of blood glucose level 2 a If the blood glucose level is too high, cells lose water by osmosis and their metabolic activities will be affected. Glucose may be lost in urine. 85
18. 2 Regulation of blood glucose level 2 b. If the blood glucose level is too low, cells cannot obtain enough energy for metabolism and they may die. 86
1 What is the relationship between diabetes mellitus and insulin? When the pancreas fails to secrete enough insulin, a person will have diabetes mellitus. 87
2 Why do people with diabetes mellitus need to check their blood glucose levels and receive insulin injections regularly? Since the blood glucose level varies with body activities, it is necessary to check the level and inject suitable amounts of insulin regularly. 88
3 What other modern advances in science and technology may help control or cure diabetes mellitus? Other than insulin injections, diabetes mellitus may be controlled or cured by pancreas transplant. 89
Homeostasis is brought about by nervous system endocrine system through negative feedback mechanism 90
Homeostasis is the maintenance of a stable internal environment parameters include water content in blood body temperature glucose level gas content in blood 91
glucose level in blood is regulated by insulin glucagon act on secreted by pancreas liver body cells 92
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