163b Metabolism II Flashcards Preview

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Flashcards in 163b Metabolism II Deck (19):
1

insulin

B cells in interior of islets of Lagerhans

Anabolic role

regulated by blood glucose levels - keeps glucose in narrow range

2

glucagon

a cells in exterior of islets of langerhans

3

glucagon-like peptide-1 (GLP-1)

L cells in jejunum in response to feeding

4

Leptin

peptide from adipocytes

5

Ghrelin

epsilon cells of inselts of langerhans and gut

fasting increases secretion

induces hunger and decreases E expenditure

6

insulin synthesis

pre-proinsulin (A,B, C chains) --> insulin + C-peptide

stored in vesicles for quick release during meals

insulin t1/2 - 5 minutes --> measuring this isn't useful, C-peptide has a much longer t1/2 - few hours

7

regulation of insulin secretion

GLUT-2 brings in glucose
ATP is made
ATP-sensitive K channel shuts --> depolarization
Ca channels open
Vesicles are released

8

how does insuling lower glucose?

myocytes and adipocytes increase glucose uptake (not in CNS - independent of insulin)

decreased glycogen breakdown/increased glycogen production in liver

decreased glucagon production

9

what tissue is indep of insulin

brain, RBC, liver

10

insulin receptor

membrane bound receptor --> tyrosine kinase receptors --> auto P --> IRS-1 P --> GLUT 4 insertion from vesicles (insulin dependent glucose transporter)

11

hepatocyte - insulin effect on glucose metabolism

increases G1P --> glycogen synthesis via glycogen synthase

12

insulin effect on adipose tissue

GLUT4 --> increased glucose --> increased fatty acids --> TG

13

insulin and muscle

increased glycogen production and protein production

14

what stimulates insulin secretion?

++
glucose
GLP-1
glucagon

--
inflammatory cytokines --> why post surgery people
NE

15

glucagon effect on insulin secretion

stimulates insulin secretion

16

glucagon action in liver cells

increase glycogen --> G1P via deactivation of glycogen synthase

increases gluconeogensis
---> acetyl CoA can't be coverted back to pyruvate (Glucagon causes free fatty acids --> acetyl CoA --> ketone bodies)

17

what causes glucagon secretion?

- glucose, insulin

18

GLP-1 fxn

increases sensitivity of B cells to glucose --> increases insulin secretion in response to glucose

19

leptin

adipocytes - in proportion to fat mass

sensor for fat storage/E reserves

induces satiety/E expenditure in hypothalamus

obesity --> defective leptin via resistance