U1-KA4-COMMUNICATION AND SIGNALLING 2)insulin and recruitment of glut4

Question 1

what is diabetes mellitus

Answer 1

a disease caused by defects in the insulin signalling system

Question 2

the two types of diabetes

• how are they caused
• treatment

Answer 2

type 1:

• destruction of beta cells in pancreas by immune system
• pancreas does not produce any insulin
• this occurs in childhood
• daily insulin injections and management of diet to control blood glucose concentration

type 2

• exact cause is unknow, but obesity is a large risk factor
• target cells develop insulin resistance - have loss of receptor function
• individuals produce insulin but their cells are less sensitive to it. This insulin resistance is linked to a decrease in the number of insulin receptors in the liver, leading to a failure to convert glucose to glycogen.
• to control this : eat less sugar and saturated fats , regular exercise and ,medication to lower blood glucose concentration.

Question 3

what limits should blood glucose levels be kept in

Answer 3

• blood glucose levels must be kept within narrow limits , between 3.9 and 6.1 mmol per litre of blood

Question 4

how are blood glucose levels controlled (from your previous higher knowledge)

Answer 4

• the peptide hormones insulin and glucose interact in a negative feedback system to control blood glucose level.
• when blood glucose conc increases above normal , pancreas secretes more insulin which is secreted into blood.
• insulin is transported to the liver where it converts glucose to glycogen , decreasing blood glucose conc
• when blood glucose decreases , pancreas secreted more glucagon which is secreted into the blood.
• glucagon is transported to the liver where the liver concerts glycogen to glucose bringing glucose levels up to normal

Question 5

what happens if blood glucose levels rise

Answer 5

• if blood glucose level rises, foe example after a meal, the pancreas detects the increase in blood glucose. this causes it to increase the secretion of insulin

Question 6

talk about how insulin controls glucose levels in detail (kinase linked receptor)

Answer 6

• the insulin receptor is a kinase linked receptor found in the cell membrane of fat and muscle cells.
• once the peptide hormone insulin binds to its receptor, a conformational change takes place, and the signal is transduced triggering a series of kinase catalysed phosphorylation events(an intracellular signalling cascade) that triggers the recruitment of GLUT4 transporters to the cell membrane. (vesicles containing GLUT4 which are recruited into the cell membrane )
• these transporters allow glucose to enter these cells , where it can be converted to glycogen or used in glycolysis and thus blood glucose concentration is controlled,

Question 7

how does exercise reduce the impact of type 2 diabetes

Answer 7

• exercise reduces the impact of type 2 diabetes as it triggers the recruitment of GLUT4 through other metabolic pathways : exercise improves the uptake of glucose to fat and muscle cells in subjects with type 2 disease

Question 8

Fy

Answer 8

H