Hormone regulation in carbohydrate metabolism, fasting/fed state

How do endocrine hormones get to target cells

hormones enter blood stream to travel to targeted cells

What type of hormones bind to membrane receptors of targeted cells, and examples of the type

Peptide/protein and catecholamines hormones

Insulin, glucagon

epinephrine, norepinephrine, and growth hormone (GH)

how does hormones act on membrane receptors

second messenger enzyme cascade,

fast effects, activation of existing enzyme/protein and secretion of stored enzyme/protein

slow effects: transcription factor involved and gene transcription

What type of hormones bind to nuclear receptors and example

steroid and thyroid hormones

Steroid: cortisol

how do hormones act on nuclear receptors

hormone-bound receptor=transcription

plasma binding protein (lipid soluble) → cytoplasm nuclear receptors → gene transcription in hormone bound form

which hormone lowers blood glucose level

insulin

which hormone increases blood glucose level

several

which hormone is dominant in fed state condition

insulin

what is the difference in how liver, skeletal muscle, adipose, and most other cells process glucose under fed state/condition

in fed state, which organ stimulates glucose

small intestine

What are incretin hormones present and fed state, and why are they important

GIP (k-cells) and GLP-1 (L cells)

important for post-meal insulin secretion

what is the difference in how liver, skeletal muscle, adipose, and most other cells process glucose in fasting state (post-absorptive)

When is blood glucose level low (during what state)

Fasting

What hormone is dominant initially and afterwards during fasting state

initially: glucagon

afterwards: other hormones increase to maintain blood glucose

what stimulates the release of insulin

beta cells-high blood glucose levels

what stimulates the release of glucagon

low blood glucose, exercise and protein rich meals

how does insulin signals

binding to receptor on the cell’s surface, primarily involve protein phosphorylation including activation of enzymes PI3K and AKT (protein kinase)

What are major insulin signaling molecules in relevance of glycolysis

insulin receptor (IR)

insulin receptor substrates (IRS)

phosphatidylinositol-3 kinase (PI3K)

protein kinase B (AKT)

What are major insulin signaling molecules of in relevance of glycogen synthesis

insulin receptor to activate PI3-kinase pathway

activates PKB/AKT, which inactivates GSK3) and protein phosphatase 1 (PP1) is activated to dephosphorylate and active glycogen synthase

how does glucagon signal

binding to G-protein coupled receptors on target cells in the liver

pancreatic islet alpha cells

What are major glucagon signaling molecules in relevance of gluconeogenesis

cAMP, PKA

What are major glucagon signaling molecules in relevance of inhibition of glycolysis

cAMP, PKA

What are major glucagon signaling molecules in relevance of glycogen synthesis

cAMP, PKA

how does insulin regulate key enzymatic steps in glycolysis

via translocation of GLUT4 transporters to plasma membrane, indirectly increase F2,6BiP, which activates PFK

how does insulin regulate key enzymatic steps in gluconeogenesis

suppressing PEPCK and G6Pase

how does glucagon regulate key enzymatic steps in glycolysis

decreasing concentration of F-2,6-BiP by activating enzyme FBP-ase2, which inhibits PFK1

indirectly downregulates PK

in glycogenolysis how does glucagon regulate key enzymatic steps

glucagon binding to G-protein coupled receptor—> increase in cAMP and activation of PKA—> PKA phosphorylates—> activates glycogen phosphorylase—> inactivates glycogen synthase

in gluconeogenesis, how does glucagon regulate key enzymatic steps

stimulates production of cAMP activating protein kinase A (PKA), which then phosphorylates and inhibits glycolytic enzymes, while promoting pyruvate kinase, PEPCK, and fructose 1,6-biphosphatase.

what multiple hormones regulate blood glucose

insulin and glucagon

epinephrine, cortisol, growth hormone (GH) somatostatin and amylin

Put hormone concentration changes in order, first to last, when blood glucose falls: GH increases, cortisol increases, insulin decreases, glucagon & epinephrine increase

insulin decreases

glucagon & epinephrine increase

GH increase

cortisol increases