Control of Blood Glucose

Question 1

What is negative feedback?

Answer 1

any deviation from normal values/conditions are restored to their original levels

Question 2

What impacts blood glucose?

Answer 2

• increases after ingesting food/drinks with CHOs
• decreases following exercise or after not eating for a period of time

Question 3

What cells release insulin and glucagon and where are they found?

Answer 3

alpha cells: glucagon
beta cells: insulin
found in the Islets of Langerhans in the Pancreas

Question 4

What does insulin do? (4 points)

Answer 4

• binds to complementary receptors on cell membrane of liver and muscle cells
• widens channels/increases permeability
• stimulates vesicles containing carrier proteins to fuse with membrane
• activates enzymes

Question 5

What is meant by the term glycogenolysis?

Answer 5

hydrolysis of glycogen back into glucose in the liver

Question 6

What is meant by the term gluconeogenesis? When does it occur?

Answer 6

glucose being made from non-CHO stores in the liver, when all glycogen has been converted and glucose level is still too low

Question 7

How does insulin attaching to receptors on target cells reduce blood glucose levels?

Answer 7

changes tertiary structure of channel proteins resulting in more glucose being absorbed by facilitated diffusion

Question 8

How does insulin activating enzymes lower blood sugar?

Answer 8

more glycogenesis

Question 9

How does an increase in protein carriers lower blood sugar levels?

Answer 9

more glucose is absorbed into cells (larger SA for facilitated diffusion)

Question 10

How does insulin attaching to receptors on target cells increase the number of carrier proteins?

Answer 10

• stimulates intracellular chemical to be produced
• causes vesicles containing carrier proteins to fuse to membrane

Question 11

How does the binding of glucagon increase blood sugar levels?

Answer 11

bind to complementary receptors, activating a protein to become adenylate cyclase

Question 12

What is the role of adenylate cyclase?

Answer 12

• converts ATP into cyclic AMP

Question 13

How does activating enzymes result in increase blood glucose levels?

Answer 13

• stimulates enzymes to carry out gluconeogenesis (from glycerol or a/a)
• secondary messenger system activates enzyme that breaks down glycogen to glucose

Question 14

What activates adenyl cyclase?

Answer 14

change in tertiary structure caused by G- subunit binding to its receptor on the inside of the membrane

Question 15

What is the second messenger? what does it activate?

Answer 15

cAMP, protein kinase

Question 16

What proteins does adrenaline activate?

Answer 16

G proteins (that convert ATP into cAMP)

Question 17

what is glycogenesis?

Answer 17

the formation of glycogen from glucose

Question 18

What is the role of cAMP?

Answer 18

activates the enzyme protein kinase which carries out glycogenolysis

Question 19

What are four ways blood glucose concentration is lowered?

Answer 19

• increased rate of absorption of glucose into cells
• increase in respiratory rate in cells
• increased glycogenesis
• increased rate of conversion of glucose to fat

Question 20

Describe the actions of glucagon…

Answer 20

• increases blood glucose concentration
• attachment to specific receptors on cell-surface membranes
• activate enzymes that convert glycogen to glucose
• activates enzymes involved in gluconeogenesis

Question 21

How does adrenaline regulate blood glucose?

Answer 21

• raises blood glucose
• attaches to protein receptors on cell membranes of target cells
• activates enzymes that cause the breakdown of glycogen to glucose in the liver