Mark's Biochem 26: Basic Concepts In The Regulation Of Fuel Metabolism By Insulin, Glucagon, And Other Hormones

Front 1

metabolic homeostastis is achieved via

Back 1

1) concentration of nutrients/metabolites in blood affect rate of use/storage by tissues 2) hormones carry messages 3) CNS uses neural signals to control tissue metabolism (directly or via hormones)

Front 2

what is the minimum required glucose in a day

Back 2

190 g - 140 for brain and 40 for other tissues

Front 3

decrease of blood glucose below what level limits brain glucose metabolism

Back 3

<60 mg/dL; dur to Km values of glucose transporters required

Front 4

glucagon sites of action

Back 4

liver and adipose tissue (muscle cells lack glucagon receptors)

Front 5

when do highest levels of insulin occur

Back 5

30-45 minutes after a high carb meal; return to basal levels ~120 minutes after meal

Front 6

what is the release of cortisol, epinephrine, and norepi mediated by? How about insulin and glucagon?

Back 6

neuronal signals; glucose concentration

Front 7

elevated epi levels cause

Back 7

tachycardia, palpitations, anxiety, tremulousness, pallor, and sweating

Front 8

hypoglycemic symptoms

Back 8

fatigue, confusion, blurred vision

Front 9

insulin structure

Back 9

2 polypeptide chains linked by two interchain disulfide bonds

Front 10

formation of insulin

Back 10

preprohormone converted to prohormone in RER; microvesicles to golgi - storage vesicles have protease that removes the C-peptide forming insulin

Front 11

zinc and insulin

Back 11

zinc is transported into insulin storage vesicles; once C-peptide removed insulin is less soluble and co-precipitates with Zinc

Front 12

transporters in B-cells that allow glucose entry

Back 12

GLUT-2

Front 13

what forms glucose 6-phosphate

Back 13

glucose phosphorylation via glucokinase

Front 14

What happens in B-cells as ATP/ADP ratio increases

Back 14

activity of membrane-bound ATP-dependent K+ channel is inhibited causing membrane depolarization

Front 15

genetic susceptability to diabetes type I

Back 15

human leukocyte antigen (HLA) region of B-cels that codes for the major histocompatibility complex II (MHC II)

Front 16

threshold for insulin release

Back 16

80 mg/dL

Front 17

what gastric hormones aid in insulin release

Back 17

GIP and GLP-1

Front 18

MODY mutations

Back 18

in glucokinase or specific nuclear transcription factors

Front 19

most common mutation leading to permanent neonatal diabetes

Back 19

KCNJ11 which encodes a subunit of the K+ channel in various tissues

Front 20

glipizide

Back 20

sulfonylurea drug; act on K+ channels of B-cells - bind and inactivate causing insulin release

Front 21

direction of blood flow in the pancreas importance

Back 21

carries insulin from B-cells in center of islets to peripheral a-bells where it supresses glucagon secretion

Front 22

why would aas stimulate glucagon and insulin secretion (like after a high protein meal)

Back 22

insulin stimulate uptake and protein synthesis, glucagon stimulates gluconeogenesis

Front 23

wha provides an acurate estimate of insulin secretion rate

Back 23

C-peptide - secreted in equal amounts as insulin, but not cleared as quickly

Front 24

3 basic types of signal transduction for hormones binding to receptors on the plasma membrane

Back 24

1) receptor coupled adenylyl cyclase 2) receptor kinase activity 3) receptor coupled hydrolysis of PIP2

Front 25

insulin receptor

Back 25

2 alpha, 2 beta subunits; cytosolic B has tyrosine kinase activity

Front 26

principle substrate of insulin receptor phosphorylation

Back 26

insulin-receptor substrate-1 (IRS-1)

Front 27

5 basic tissue responses to insulin

Back 27

1) reverses glucagon-stimulated phosphorylation 2) cascade to activate several enzymes 3) induces and represses synthesis of specific enzymes 4) GF and stimulatory effect on protein synthesis 5) stimulates glucose and aa transport into cells

Front 28

in diabetes type I and II, what other hormone besides insulin has a change in concentration

Back 28

glucagon - normally inhibited by insulin

Front 29

glucagon signaling cascade

Back 29

adenylyl cyclase to cAMP via G proteins to protein kinase A to enzyme phosphorylation (at specific serine residues)

Front 30

3 beta-adrenergic receptors

Back 30

work via adenylate cyclase-cAMP system

Front 31

B1 receptor

Back 31

major adrenergic receptor in the heart; primarily stimulated by norepi

Front 32

B2-receptor

Back 32

liver, skeletal muscle, and other tissues; mobilization of fuels, mediates vasculat, bronchial, and uterine smooth muscle contraction; epi>norepi

Front 33

a3-receptor

Back 33

mostly adipose tissue, some skeletal muscle; stimulates fatty acid oxidation and thermogenesis

Front 34

one of most important cellular responses to insulin

Back 34

reversal of glucagon-stimulated phosphorylation of enzymes

Front 35

phosphoenolpyruvate carboxykinase

Back 35

key enzyme of gluconeogenic pathway; increased by glucagon, decreased by insulin