B2.047 Hormonal Regulation of Glucose Homeostasis Flashcards Preview

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Flashcards in B2.047 Hormonal Regulation of Glucose Homeostasis Deck (41)
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1

what are the 5 type of pancreatic cells and what do they secrete?

beta- insulin
alpha- glucagon
delta- somatostatin
F- pancreatic polypeptide
epsilon- ghrelin

2

describe the steps of glucose mediated insulin secretion in the beta cells

passive glucose transport into cell via GLUT2
glucose metabolism in mitochondria
ATP mediated inhibition of K+ channel
cell depolarization
activation of voltage gated ca2+ channel
Ca2+ influx stimulates vesical mediated secretion

3

what mediators in addition to glucose can activate the voltage gates Ca2+ channel?

glucagon
GLP1
anything that increases ATP

4

at approx. what blood glucose levels does insulin secretion begin and level off?

begin 100 mg/ 100 mL
level 500 mg/ 100 mL

5

how can plasma free fatty acids both stimulate and suppress B cell function?

stimulate- can increase ATP via fatty acid metabolism
suppress- very high levels like in obesity can inhibit B cell sensitivity

6

what are the 2 primary inhibitors of beta cell function?

sympathetic stimulation (epinephrine, norepinephrine)
delta cell (somatostatin)

7

what type of state does insulin promote?

anabolic- stores fuels

8

how does insulin impact liver glucose release?

inhibits it by phosphorylating glucose

9

how doe insulin impact amino acids?

stimulates active transport into cells
stimulates protein synthesis
decreases protein breakdown

10

how does insulin impact fatty acids?

increases uptake by adipose
inhibits hormone sensitive lipase

11

what are the primary sites of insulin action?

liver, muscle, adipocytes

12

how is GLUT1 regulated

increased by growth factors, hypoglycemia, and PPAR gamma (TZDs)
decreased by hyperglycemia

13

where is GLUT2 expressed?

pancreatic B cells, liver, intestine, kidney

14

what two mechanisms mobilize GLUT4 in muscle and adipocytes?

insulin
exercise

15

what can suppress GLUT4 mobilization?

FFAs

16

what is the main target and primary regulator of glucagon?

the liver
glucose regulated

17

what are the two primary inhibitors of glucagon?

insulin
somatostatin

18

what state does glucagon promote?

catabolic- fuel breakdown

19

how are liver proteins impacted by glucagon?

stimulates hepatic proteolysis
stimulates liver AA uptake
stimulated hepatic ureagenesis (ammonia disposal)

20

how are TG breakdown proteins used?

FA- liver converts to ketones (CNS, muscle, heart)
glycerol- liver uses for gluconeogenesis

21

what stimulated somatostatin secretion?

glucose and AA

22

what is the function of somatostatin?

slow gastric emptying
fine tune nutrient absorption and utilization

23

what levels of I:G ratio are associated with each metabolic status?

fed: 30
O/N fast: 2
prolonged fast: 0.5
DM: imbalance

24

what hormones in addition to glucagon and insulin and important in glucose homeostasis? where do they come from?

growth hormone: anterior pituitary
cortisol: adrenal cortex
epinephrine: adrenal medulla
thyroid hormone: thyroid gland

25

how are catecholamines regulated by hypoglycemia?

hypoglycemia induces sympathetic neuronal activity in the adrenal medulla

26

how are growth hormone and cortisol regulated by hypoglycemia?

hypoglycemia induces a CNS response in the hypothalamus ultimately leading to increased hormone secretion

27

how does growth hormone regulate tissues in glucose homeostasis?

adipose: stimulates lipolysis
liver: stimulates gluconeogenesis
decreases glucose uptake by tissues by increasing FFA and inducing insulin resistance

28

how do glucocorticoids regulate homeostasis?

alter gene expression
slow acting, more "chronic" regulators than other hormones

29

what 4 functions do glucocorticoids help regulate?

metabolism
inflammation
circulation
development

30

what metabolic enzymes are regulated in part by glucocorticoids?

PEPCK
gluc-6-phosphatase
lipolytic agents