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

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

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

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

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

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?

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

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 …

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 …

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 …

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

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

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

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

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

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

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

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

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?

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

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?

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

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

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

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

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

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

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

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,

18.1 The concept of homeostasis 1 is the ability of the body to maintain a stable internal environment. Homeostasis

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

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

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

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

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

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

Negative feedback mechanism 18.1 The concept of homeostasis 5 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

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?

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

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

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.

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

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

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

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?

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

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

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

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

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

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

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

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

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?

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

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

http://www.sunyniagara.cc.ny.us/val/pancreas2.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. http://www.cytochemistry.net/microanatomy/Endocrines/pancreas2.jpg

 cells of islets of Langerhans 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  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

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

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

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

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)

Complications related to Diabetes

Insulin Pump

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

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

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

New device for controlling diabetes mellitus

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

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

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

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

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

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

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

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

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.

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.

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

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

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