16.3 hormones & the regulation of blood glucose concentration

Question 1

where are islets of langerhans produced?

Answer 1

hormone-producing cells in pancreas

Question 2

which type of islets are larger & what does it produce?

Answer 2

alpha, glucagon

Question 3

what is the smaller islet and what does it produce?

Answer 3

beta, insulin

Question 4

what is glycogenolysis?

Answer 4

breakdown of glycogen -> glucose

Question 5

what is glycogenesis?

Answer 5

converting glucose -> glycogen

Question 6

what is gluconeogenesis?

Answer 6

production of glucose from other sources than carbohydrates

Question 7

what are 2 examples of other sources for gluconeogenesis?

Answer 7

glycerol & fatty acids

Question 8

where is insulin & glucagon secreted?

Answer 8

blood plasma

Question 9

describe the negative feedback loop in stimulating insulin secretion.

Answer 9

1) stimulus: increase in blood glucose concentration
2) receptors: B-cells islets in pancreas
3) insulin secreted in blood plasma
4) increase in rate of absorption in the muscle cells -> higher respiratory rate / increase rate of glycogenesis in liver & muscles / higher rate of converting glucose to fat
5) negative feedback: insulin production switched off

Question 10

describe the negative feedback loop of glucagon secretion.

Answer 10

1) stimulus: increase in blood glucose concentration
2) receptors: a-cell islets in pancreas
3) glucagon secreted in blood plasma
4) glycogenolysis / gluconeogenesis enzymes are activated
5) negative feedback: glucagon production is switched off

Question 11

how does insulin remove glucose from the blood?

Answer 11

insulin molecules bind to glycoproteins on cell-surface membrane on all body cells
-> receptors changes tertiary structure of glucose transport carrier molecules & opens
-> more glucose in by facilitated diffusion

Question 12

where is adrenaline produced?

Answer 12

adrenal glands above the kidneys

Question 13

how does adrenaline help regulating blood glucose level?

Answer 13

attach to protein receptors on cell-surface membrane of target cells
-> activates enzymes that cause glycogenolysis

Question 14

describe the second messenger model of adrenaline & glucagon action.

Answer 14

1) adrenaline bins to transmembrane protein receptors within cell-surface membrane of liver cells
-> protein changes shape ion inside of membrane
2) activates adrenal cyclase (which converts ATP -> cAMP)
3) cAMP binds to protein kinase & activates it by changing its shape
4) protein kinase catalyses conversion of glycogen -> glucose; therefore glucose moves out of liver cells by facilitated diffusion & into bloodstream through channel proteins