Regulation of Glucose regulation

Question 1

What is glycogenesis?

Answer 1

formation of glycogen from glucose

Question 2

What is glycogenolysis?

Answer 2

catabolism glycogen- to restore blood glucose levels

Question 3

What is gluconeogenesis?

Answer 3

synthesis glucose from other sources, glycerol, amino acids (non -CHO)

Question 4

What is hyperglycaemia?

Answer 4

high blood glucose

Question 5

What is hypoglycaemia?

Answer 5

low blood glucose

Question 6

What happens when blood glucose levels fall?

Answer 6

• alpha cells sense a decrease in glucose in blood flowing through pancreas: secrete glucagon
• glucagon activates glycogenolysis
• glucose diffuses into blood to increase blood glucose
• if glycogen in liver is low, glucagon activates gluconeogenesis: glucose synthesised from pyruvate, amino acids
• increased blood glucose- decease glucagon

Question 7

What happens when blood glucose rises?

Answer 7

• beta cells sense an increase in glucose in blood flowing through pancreas; secrete insulin inti bloodstream
• insulin binds to receptors on cells surfaces
• changes the tertiary structure if glucose transporter proteins allowing more glucose to enter cell by facilitated diffusion
• increases number of glucose transporter proteins at cell surface; by causing fusion of intracellular vesicles with cell surface membrane
• activation of enzymes that cause glycogenesis and fat synthesis

Question 8

How is blood glucose lowered?

Answer 8

• increased rate of absorption of glucose into cell: muscle cells
• by increasing respiratory rate: cells use up more glucose and take up more from blood
• by increasing glycogenesis in liver and muscle
• by increasing conversion of glucose into fat

Question 9

How does adrenaline increase glucose levels?

Answer 9

• The hormone approaches the transmembrane protein
• Adrenaline fuses to the receptor causing it to change shape on the inside of the membrane activating an enzyme called adenyl cyclase inside the membrane
• the activated adenyl cyclase converts ATP to cAMP which acts as a second messenger
• the cAMP in turn changes the shape and activates the protein kinase enzyme
• the active protein kinase enzyme catalyses the conversion of glycogen to glucose