Homeostasis-control of blood glucose concentration

Question 1

what are factors that affect blood glucose concenteration?

Answer 1

1. diet; cuases an increased after a carbohydrate rich meal
2. fasting and excersice; cuases a deacrease
3. glycogenolysis, gluconeogenesis

Question 2

what is the role of the liver in maintaining blood gluocse concenteration?

Answer 2

1. have complmentory receptors to insulin and glucagon
   2a. if the blood glucose concenteration is too high, more glucose transporters to be targeted, increases the uptake the glucose
   2b. causes signalling cascased, results in the activation of glycogen synthase, increasing glycogensis.
2. if blood glucose concentration is too low, receptors activate the adenyl cyclase, activating glyconeolysis

Question 3

what is the role of glycogenolysis in maintaing blood glucose concenteration?

Answer 3

1. glycogenolysis is the conversion of glucose into glycogen
2. important when the blood glucose concenteration is too high and needs to be lowered
3. only occurs at the liver and muscle cells

Question 4

what is the role of gluconeogenesis in maintaing blood glucose concenteration?

Answer 4

1. is the production of glucose from sources other than carbohydrates
2. mainly occurs in the liver
3. occurs when the body does not have access to carbohydrates; after long period of not eating/fasting

Question 5

how does insulin work to maintain blood glucose concenteration?

Answer 5

1. insulin binds to complementory receptors in the surface of liver/muscle cells
2. this changes the tertiary structure of the glucose transporters, causing them to take up more glucose by facilitated diffusion
   or
3. this increases the no. glucose carrier proteins
4. activates enzymes that convert glucose to glycogen
   note: beta cells in the islets of langerhans detect the high blood glucose concenteration and secrete insulin into the blood stream

Question 6

how does glucagon work to maintain blood glucose concenteration?

Answer 6

1. beta cells in the islets of langerhans detect low blood glucose concenteration
2. secretes glucagon into the bloodstream, binds to receptors on the surface of liver cells
3. receptors activate enzymes that convert glycogen to glucose; glycogenolysis
4. activates enzymes that convert amino acids and glycerol into glucose; gluconeogenosis

Question 7

what is the role of adrenaline in maintaing blood glucose concenteration?

Answer 7

1. released from the adrenal glands
2. attaches to protein receptors on the target cells
3. activates enzymes that cause the breakdown of glycogen to glucose in the liver; glycogenolysis

Question 8

what is the second messenger model of adrenaline and glucagon action?

Answer 8

1. adrenaline and glucagon receptors have specific tertitary structures that make them complementory to respective substrate
2. adrenaline and glucagon bind to receptors and activate enzyme andenylate cyclase (on inner membrane surface)
3. activated adenylate cyclase converts ATP into a chemical signal called a ‘second messenger’- cyclic AMP
4. cAMP activates protein kinase A, protein Kinase A activates a cascade that breaks down glycogen into glucose- glycogenolysis

Question 9

what are the causes of type 1 diabates?

Answer 9

1. immune system attacks the beta cells in the islets of langerhans
2. cannot produce insulin
3. may be caused by a genetic disposition or viral infection

Question 10

what are the causes of type 2 diabetes?

Answer 10

1. aquired later in life, often linked to obseity
2. more likely in people with a family history
3. lack of exercise, age and poor diet
4. beta cells do not produce enough insulin or body cells don’t respond to insulin, receptors don’t work

Question 11

how is type 1 diabetes controlled/treated?

Answer 11

1. treated with insulin therapy; regular insulin injections or using an insulin pump
   - must be carefully controlled, too much insulin may cause hypoglycemia
2. eating regularly
3. controlling simple carbohydrate intake

Question 12

how is type 2 diabetes controlled/ managed?

Answer 12

1. eating health balanced diet
2. loosing weight
3. regular exercise
4. glucose-lowering medication
5. insulin injections