Endocrine Pancreas Physiology

Question 1

acinar cells

Answer 1

exocrine pancreas cells that produce and secrete digestive enzymes

Question 2

islet of langerhans

Answer 2

endocrine pancreas cells; produces hormones

Question 3

what are the cell types in the islet of langerhans and what do they secrete

Answer 3

a cells: glucagon
B cells: insulin
D cells: somatostatin
F cells: pancreatic polypeptide

Question 4

what stimulates insulin secretion

Answer 4

high blood glucose

Question 5

net effect of insulin & target tissues

Answer 5

decrease blood glucose

targets:
- liver
- muscle
- adipose

Question 6

insulin effects in the liver

Answer 6

lowers hepatic glucose production

stimulates glycogenesis
inhibits glycogenolysis and gluconeogenesis

Question 7

insulin effects in muscle

Answer 7

stimulates glucose uptake via GLUT4
stimulates AA uptake
stimulates protein synthesis

Question 8

insulin effects in adipose tissue

Answer 8

stimulates glucose uptake via GLUT4
stimulates lipogenesis
inhibits fat mobilization

Question 9

how is insulin secreted

Answer 9

Ca dependent activation

1. glucose enters B cell through GLUT2 channels
2. glucose gets converted to G6P then to ATP
3. ATP causes K+ channels to close and Ca2+ channels to open
4. Ca influxes into the cell and stimulates insulin release via exocytosis of secretory granules

Question 10

ANS regulation of insulin secretion

Answer 10

B cells are innervated by both PNS and SNS

1. cephalic phase - PNS predominates to increase insulin secretion during meal/fed state
2. stress induced - SNS predominates to decrease insulin secretion (want high BG to make glucose available to brain)

Question 11

what stimulates glucagon secretion

Answer 11

low blood glucose

amino acids (during high protein meal to prevent hypoglycemia from lack of carbohydrates)

Question 12

net effects of glucagon & target tissues

Answer 12

increases blood glucose

targets:
- liver
- adipose

Question 13

glucagon effects in the liver

Answer 13

increases hepatic glucose production
- stimulates glycogenolysis
- stimulates gluconeogenesis

Question 14

glucagon effects in adipose

Answer 14

stimulates lipolysis and FFA efflux

Question 15

effects of somatostatin

Answer 15

inhibits secretion of insulin and glucagon

Question 16

can somatostatin be used as a treatment for diabetes

Answer 16

short half life makes it difficult

would need a long lasting, glucagon specific somatostatin to avoid inhibition of insulin

Question 17

diabetes mellitus

Answer 17

failure to normally regulate blood glucose concentrations leading to hyperglycemia

Question 18

what species is diabetes mellitus common in

Answer 18

dogs and cats

usually middle aged

Question 19

clinical signs of diabetes mellitus

Answer 19

• hyperglycemia
• glucosuria
• PU/PD
• weight loss
• ketosis –> DKA

Question 20

at what point (BG) do you start to see glucosuria

Answer 20

when blood glucose exceeds the renal transport capacity/threshold (>180; species variations)

Question 21

what is the mechanism of PU/PD in diabetes

Answer 21

glucosuria –> osmotic diuresis –> water flows into renal tubules –> PU –> dehydration –> PD

Question 22

what is the mechanism of ketosis in diabetes

Answer 22

inability of blood glucose to enter into tissues –> tissues rely on muscle and adipose for energy –> formation of ketone bodies –> acidifies the blood

Question 23

how is a diagnosis of DM made

Answer 23

clinical signs
hyperglycemia +/- glucosuria

Question 24

what are common complications associated with diabetes mellitus

Answer 24

• retinopathy (blindness/cataracts)
• nephropathy
• neuropathy

Question 25

type I diabetes

Answer 25

“insulin dependent”

low/absent insulin production from pancreas

Question 26

cause of type I diabetes

Answer 26

• autoimmune mediated destruction of B cells
• pancreatitis/isletitis

Question 27

how to treat type I diabetes

Answer 27

exogenous insulin administration

want to avoid hypoglycemia

can monitor long term with fructosamine or HbA1c

Question 28

what species is type I diabetes most common in

Answer 28

dogs

genetic predispositions: keeshonds, poodles, dachshunds, beagles

Question 29

type II diabetes

Answer 29

“non-insulin dependent”

BOTH:
- insulin resistance
- impaired insulin secretion

requires both mechanisms because if it was only insulin resistance, the pancreas would produce more insulin to overcome the resistance

Question 30

cause of type II diabetes

Answer 30

lifestyle/obesity leading to insulin resistance

risk factors:
- age (older)
- gender (male)
- neutering
- low activity
- corticosteroid administration

Question 31

how to treat type II diabetes

Answer 31

lifestyle modification (diet weight loss)

later stages of disease become insulin dependent - requires exogenous insulin administration

Question 32

what species is type II diabetes most common in

Answer 32

cats

Question 33

what BG value is considered hypoglycemic

Answer 33

plasma glucose < 50-60 mg/dL

severe: <30 mg/dL

Question 34

causes of hypoglycemia

Answer 34

• excess insulin in diabetic treatment (common)
• insulinoma
• prolonged fasting in young animals
• severe infections
• Addison’s disease (dec. corticosteroids)
• xylitol poisoning in dogs

Question 35

clinical signs of hypoglycemia

Answer 35

hunger
drowsiness
dull mentation
palpitations
convulsions
coma
brain damage