Pancreas – insulin and its metabolic effects. Control of insulin secretion. Diabetes

Question 1

pancreas - intro

Answer 1

organ needed for regulation of metabolism/ blood sugar homeostasis

Question 2

pancreas - structure 1

Answer 2

exocrine pancreas

• made of acinar cells producing digestive enzymes amylase/ protease/ lipase
• made of duct cells producing bicarbonate ions
• needed for carbohydrate/ protein/ fat metabolism

Question 3

pancreas - structure 2

Answer 3

endocrine glands

• contain islet of langerhans which made of 3 main cells to release hormones

beta cells = insulin
alpha cells = glucagon
delta cells = somatostatin

Question 4

insulin - formation

Answer 4

preproinsulin gets processed in ER to produce proinsulin gets processed in golgi to produce active insulin + C-peptide

Question 5

insulin - function

Answer 5

after eating
- blood glucose rises
- pancreas to release insulin to absorb glucose
- blodo glucose goes down

glucose converts into glycogen for storage
- muscle
- adipose

Question 6

insulin - effect 1

Answer 6

glycogenesis = converstion of glucose -> glycogen in liver/ muscle

Question 7

insulin - effect 2

Answer 7

inhibits gluconeogenesis

production of new glucose molecules from non carb sources in liver

Question 8

insulin - effect 3

Answer 8

inhibits glycogenolysis

break down of glycogen -> glucose in liver/ muscles

Question 9

insulin - effect 4

Answer 9

lipogenesis

fatty acids + glycerol -> triglycerides via acetyl coa carboxylase in adipose tissue

Question 10

insulin - effect 5

Answer 10

inhibits lipolysis

breakdown of triglycerides -> fatty acids + glycerol

Question 11

insulin - effect 6

Answer 11

protein synthesis in muscles by increasing uptake of amino acids

Question 12

insulin - effect 7

Answer 12

prevents protein breakdown as it wants to keep amino acids

Question 13

control of insulin secretion - 1

Answer 13

glucose enters beta cells by GLUT transporters
glucose is metabolised to produce ATP
voltage gated potassium ion channels close
voltage gated calcium ion channels open = influx of ca2+
calcium influx -> insulin vesicles released into bloodstream

Question 14

control of insulin secretion - 2

Answer 14

high levels of amino acids like arginine/ leucine = insulin release

so after high protein meal, insulin is released to help uptake of amino acids into tissues for protein synthesis

Question 15

control of insulin secretion - 3

Answer 15

hormones

• glucagon-like peptide 1
• gastric inhibitory peptide
• help ingest food
• enhance insulin secretion

Question 16

control of insulin secretion - 4

Answer 16

ANS

PNS = increases insulin secretion
SNS = decreases insulin secretion

Question 17

control of insulin secretion - 5

Answer 17

negative feedback

insulin function to lower blood glucose conc when its too high using neg/ feedback

Question 18

diabetes - definition

Answer 18

abnormal metabolism of gluocose

Question 19

diabetes - type 1

Answer 19

• autoimmune disease

own body cells to attack islet of langerhans beta cells so cannot produce insulin = absolute insulin deficiency

no insulin = glucose cannot enter cells = hyperglycemia

body breaks down fat/ muscle for energy which produces ketones = ketoacidosis

treated by life long insulin therapy injections/ pumps

Question 20

diabetes - type 2

Answer 20

when muscle/ fat/ liver cells become less responsive to insulin = insulin resistance

they cannot uptake

pancreas cannot produce enough insulin to compensate this resistance

Question 21

diabetes - type 2

EFFECT 1

Answer 21

higher circulating insulin = hyperinsulinemia

Question 22

diabetes - type 2

EFFECT 2

Answer 22

elevated blood glucose

Question 23

diabetes - type 2

EFFECT 3

Answer 23

liver will produce more glucose by gluconeogenesis

Question 24

diabetes - type 2

TREATMENT

Answer 24

lifestyle changes - diet/ exercise

medication - metformin

Question 25

diabetes - type 3

Answer 25

gestational diabetes

• during pregnancy due to hormonal changes/ insulin resistance causing elevated blood glucose conc