2. Think about…
18.1 The concept of homeostasis
18.2 Regulation of blood glucose level
Recall ‘Think about…’
Summary concept map

3. Do you know what homeostasis is?
18.1 The concept of homeostasis
Do you know what homeostasis is?

4. 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

5. What is homeostasis? For example:
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

6. What is homeostasis? For example:
18.1
The concept of homeostasis
What is homeostasis?
blood
For example:
capillary
The condition of blood and tissue fluid is kept constant for proper functions of cells
body cell bathed in tissue fluid

7. What parameters must be kept constant in our body?
18.1
The concept of homeostasis
Parameters of the internal environment to be kept stable
What parameters must be kept constant in our body?

8. water potential of tissue fluid
18.1
The concept of homeostasis
1 Water content in blood
water content in blood
water potential of tissue fluid
affects

9. 1 Water content in blood or
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 …

10. 1 Water content in blood If too much water is gained … 18.1
The concept of homeostasis
1 Water content in blood
If too much water is gained …

11. 1 Water content in blood If too much water is lost … 18.1
The concept of homeostasis
1 Water content in blood
If too much water is lost …

12. cells cannot function properly and may even die
18.1
The concept of homeostasis
1 Water content in blood
If too much water is lost …
cells cannot function properly and may even die

13. mammalian urinary system
18.1
The concept of homeostasis
1 Water content in blood
regulated by kidneys (腎)
ureters
kidneys
urinary bladder
urethra
mammalian urinary system

14. 2 Glucose level in blood for respiration in cells energy + CO2 + water
18.1
The concept of homeostasis
2 Glucose level in blood
for respiration in cells
glucose + O2
energy + CO2 + water
- 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

15. 2 Glucose level in blood In humans, normal range is 90–100 mg/cm3
18.1
The concept of homeostasis
2 Glucose level in blood
In humans,
normal range is 90–100 mg/cm3
maintained by
liver
pancreas

16. 3 Gas content in blood in respiration energy + CO2 + water
18.1
The concept of homeostasis
3 Gas content in blood
in respiration
glucose + O2
energy + CO2 + water
content in blood is kept steady to ensure a sufficient supply

17. 3 Gas content in blood in respiration energy + CO2 + water
18.1
The concept of homeostasis
3 Gas content in blood
in respiration
glucose + O2
energy + CO2 + water
dissolves in blood
too much / too little
affects pH of blood and tissue fluid
affects enzyme activity

18. 3 Gas content in blood regulated by breathing heartbeat 18.1
The concept of homeostasis
3 Gas content in blood
regulated by
breathing
heartbeat

19. 4 Body temperature normal range is 36.5–37C
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

20. What are the effects of failing to regulate body temperature?
18.1
The concept of homeostasis
4 Body temperature
What are the effects of failing to regulate body temperature?

21. 4 Body temperature C 44 death 42 CNS breakdown >37.5 fever 33
18.1
The concept of homeostasis
4 Body temperature C 44
death 42
CNS breakdown
>37.5
fever 33
loss of consciousness 28
muscle failure

22. Let me explain with an example.
18.1
The concept of homeostasis
Mechanism of homeostasis
by negative feedback mechanism (負反饋機制)
Let me explain with an example.
What does that mean?

23. Negative feedback mechanism
18.1
The concept of homeostasis
Negative feedback mechanism
When the room temperature (RT) is higher than the set temperature (S) …

24. Negative feedback mechanism
18.1
The concept of homeostasis
Negative feedback mechanism
RT > S
thermostat turns compressor on, cooling the air back to set temperature

25. Negative feedback mechanism
18.1
The concept of homeostasis
Negative feedback mechanism
When the room temperature (RT) is lower than the set temperature (S) …

26. Negative feedback mechanism
18.1
The concept of homeostasis
Negative feedback mechanism
thermostat turns compressor off, allowing room temperature to increase
RT < S

27. nervous system or endocrine system
18.1
The concept of homeostasis
Negative feedback mechanism
Three components:
Receptor
Detects changes in the level of the parameter
Control centre
Processes information from receptor and coordinates different organs
nervous system or endocrine system

28. Negative feedback mechanism
18.1
The concept of homeostasis
Negative feedback mechanism
Three components:
Receptor
Detects changes in the level of the parameter
Control centre
Processes information from receptor and coordinates different organs
Effector
Produces a response opposite to the original change

29. Negative feedback mechanism
18.1
The concept of homeostasis
Negative feedback mechanism
When level of parameter is higher than normal,
control centre
receptor
effector
response to decrease the level back to normal
normal level of parameter

30. Negative feedback mechanism
18.1
The concept of homeostasis
Negative feedback mechanism
response to increase the level back to normal
control centre
receptor
effector
When level of parameter is lower than normal,

31. 18.1
The concept of homeostasis
is the ability of the body to maintain a stable internal environment.
Homeostasis

32. 2 Homeostasis is important for the
18.1
The concept of homeostasis
2 Homeostasis is important for the
of organisms because it provides a stable internal environment for cells to function.
survival

33. Importance of regulating the parameter
18.1
The concept of homeostasis 3
Parameter
Importance of regulating the parameter
Water content in blood
To keep a stable water potential in cells so that they can carry out metabolic activities properly
water
potential

34. Importance of regulating the parameter
18.1
The concept of homeostasis 3
Parameter
Importance of regulating the parameter
Glucose content in blood
To provide sufficient glucose to cells for
To keep a stable water potential in blood
respiration
water
potential

35. Importance of regulating the parameter
18.1
The concept of homeostasis 3
Parameter
Importance of regulating the parameter
Gas content in blood
To provide sufficient oxygen to cells for respiration
To maintain a stable for enzymes to work
oxygen pH

36. Importance of regulating the parameter
18.1
The concept of homeostasis 3
Parameter
Importance of regulating the parameter
Body temperature
To maintain a stable temperature that is optimal for to work
enzymes

37. 4 The system and the nervous
18.1
The concept of homeostasis
4 The system and the
system coordinate different organs to achieve homeostasis.
nervous
endocrine

38. Negative feedback mechanism
18.1
The concept of homeostasis
results in responses that have opposite effects to the changes in the parameter, so that the level of the parameter can be restored to normal.
Negative feedback mechanism

39. How do the liver and pancreas regulate our blood glucose level?
18.2 Regulation of blood glucose level
How do the liver and pancreas regulate our blood glucose level?

40. both act on liver but with opposite effects
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. Roles of liver and pancreas
18.2
Regulation of blood glucose level
Roles of liver and pancreas
Insulin
decreases blood glucose level
liver cells
excess glucose
glycogen
stored in
muscles
liver
Body cells take in more glucose
body cells
glucose
CO2 + water

42. Roles of liver and pancreas
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. Roles of liver and pancreas
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. Roles of liver and pancreas
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. pancreas secretes more glucagon and less insulin
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. What will happen if blood glucose level is too high?
18.2
Regulation of blood glucose level
Failing to regulate blood glucose level
What will happen if blood glucose level is too high?

47. Failing to regulate blood glucose level
18.2
Regulation of blood glucose level
Failing to regulate blood glucose level
blood glucose level too high
water leaves cells by osmosis
normal metabolism affected
glucose passes out in urine
diabetes mellitus

48. Failing to regulate blood glucose level
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. blood glucose level (mg/100cm3)
18.2
Regulation of blood glucose level
blood glucose level (mg/100cm3)
200
healthy person
level returns to normal within a short time
150
100
normal
time (hrs) 1 2 3
glucose intake

50. blood glucose level (mg/100cm3)
18.2
Regulation of blood glucose level
blood glucose level (mg/100cm3)
200
diabetic
level remains high and then drops very slowly
150
100
normal
time (hrs) 1 2 3
glucose intake

51. blood glucose level (mg/100cm3)
18.2
Regulation of blood glucose level
blood glucose level (mg/100cm3)
200
diabetic
the drop is due to the loss of glucose in urine
150
100
normal
time (hrs) 1 2 3
glucose intake

52. diabetic glucose level in urine time (hrs) 1 2 3 glucose intake 18.2
Regulation of blood glucose level
diabetic
glucose level in urine
time (hrs) 1 2 3
glucose intake

53. Diabetics need insulin injections
18.2
Regulation of blood glucose level
Diabetics need insulin injections

54. blood glucose level (mg/100cm3)
18.2
Regulation of blood glucose level
blood glucose level (mg/100cm3)
injection of insulin
200
diabetic
level drops quickly
150
100
normal
time (hrs) 1 2 3
glucose intake

55. How about if the blood glucose level is too low?
18.2
Regulation of blood glucose level
Failing to regulate blood glucose level
How about if the blood glucose level is too low?

56. Failing to regulate blood glucose level
18.2
Regulation of blood glucose level
Failing to regulate blood glucose level
blood glucose level too low
insufficient supply of glucose for respiration
neurones cannot function
person becomes unconscious

57. Pancreatic hormones Pancreatic hormones regulate blood glucose levels
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

59. 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 % of the islet cells.

60.  cells of islets of Langerhans
SECRETORY ROLE
CELL CHARACTERISTICS
 cells of islets of Langerhans
Glucagon
% 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
 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

61. Homeostasis: Normal blood glucose level
Glucose balance
Body
cells
take up more glucose
Insulin
Blood glucose level declines to a set point; stimulus for insulin release diminishes
Stimulus:
Declining blood glucose level (e.g., after skipping a meal)
Alpha cells of pancreas stimulated to release glucagon into the blood
Glucagon
Liver breaks down glycogen and releases glucose to the blood
Blood glucose level rises to set point; stimulus for glucagon release diminishes
Rising blood glucose level (e.g., after eating a carbohydrate-rich meal)
Homeostasis: Normal blood glucose level
(about 90 mg/100mL)
Beta cells
of pancreas stimulated to release insulin into the blood
Liver takes up glucose and stores it as glycogen
High blood
glucose level

65. Hours after glucose ingestion
Diabetes can be detected
By a test called a glucose tolerance test
400
350
300
Diabetic
Blood glucose (mg/100mL)
250
200
150
100
Normal 50 1 2 1 2 3 4 5
Hours after glucose ingestion

66. Diabetes is a common 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

67. Diabetes type I and type II
Type II - due to aging, lifestyle, heredity and other lifestyle (diet) factors decreased responsiveness by cells of target organs to insulin
Type I - autoimmune disorder (destroys ability to produce insulin)

69. Complications related to Diabetes

70. Insulin Pump

71. New device for controlling
diabetes mellitus
People with diabetes mellitus (糖尿病) need to
check blood glucose level and

72. New device for controlling
diabetes mellitus
People with diabetes mellitus (糖尿病) need to
receive insulin injections
several times a day…

73. New device for controlling
diabetes mellitus
This greatly affects our daily activities.

74. New device for controlling
diabetes mellitus

75. New device for controlling
diabetes mellitus
A new device consists of a glucose sensor and an insulin pump

76. New device for controlling
diabetes mellitus
The sensor checks the blood glucose level

77. New device for controlling
diabetes mellitus
A suitable amount of insulin is released automatically into the body

78. normal blood glucose level
18.2
Regulation of blood glucose level 1
more and less secreted
insulin
glucagon
1 more is converted to in liver
glucose
high blood glucose level
blood glucose level falls
glycogen
2 more is oxidized by body cells
glucose
normal blood glucose level

79. normal blood glucose level
18.2
Regulation of blood glucose level 1
normal blood glucose level
low blood glucose level
blood glucose level rises
stored is converted to
in liver
glycogen
glucose
more and less secreted
glucagon
insulin

80. 18.2
Regulation of blood glucose level
2a If the blood glucose level is too high, cells water by osmosis and their metabolic activities will be affected. Glucose may be lost in
lose
urine

81. 18.2
Regulation of blood glucose level
2b If the blood glucose level is too low, cells cannot obtain enough energy for metabolism and they may die.
energy

82. 1 What is the relationship between diabetes mellitus and insulin?
When the pancreas fails to secrete enough insulin, a person will have diabetes mellitus.

83. 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.

84. 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.

85. negative feedback mechanism
Homeostasis
is brought about by
nervous system
endocrine system
through
negative feedback mechanism

86. stable internal environment
Homeostasis
is the maintenance of a
stable internal environment
parameters include
water content in blood
body temperature
glucose level in blood
gas content in blood

87. glucose level in blood insulin glucagon pancreas liver body cells
is regulated by
insulin
glucagon
act on
secreted by
pancreas
liver
body cells