Please enable JavaScript.
Coggle requires JavaScript to display documents.
Insulin (Key Actions of Insulin (Liver (Increases glucose uptake,…
Insulin
Key Actions of Insulin
Lowers blood glucose levels
Increases uptake of glucose by muscle, adipose, and many tissues (EXCEPT NEURONS)
Increase glycogen synthesis in liver
Inhibits glucose production in liver
Increases synthesis & storage of fat
Increases synthesis of fatty acid in liver
Inhibits breakdown of lipid in adipose tissue
Increases synthesis of proteins
Liver
Increases glucose uptake
Increases glycogenesis (glycogen synthesis)
Decrease gluconeogenesis (glucose synthesis)
Decrease glycogenolysis (glycogen breakdown)
Increase lipogenesis
Muscle
Increases glucose uptake
Increases glycogenesis
Increases amino acid uptake
Increases protein synthesis
Adipose Tissue
Increases glucose uptake
Increases free fatty acid uptake
Increases lipogenesis (lipid synthesis)
Decreases lipid breakdown
Insulin Receptor & Its Activation
Insulin receptor
Receptor Tyrosine Kinase (RTK)
Homodimer (each monomer has one alpha and beta subunit)
Binding
Activation of tyrosine kinase activity
Causes phosphorylation of many intracellular enzymes (insulin receptor substrates)
Activates other enzymes
Changes gene expression
GLUT 4 (or something similar)
In neuron
Always active
Glucose can come in anytime
Migrates to cell surface so glucose can get into cell
Tissue, liver, and lipid
More insulin activation
Increase of GLUT 4
Stimulation and Suppression that Affect Insulin Release
Stimulation
Increased in blood glucose
Glucose by mouth is a bigger stimulus compared to injection
Increased blood free fatty acids
Increased blood amino acids
Glucagon, GH, cortisol
GI hormones (incretins)
Regulated locally by glucose in GI tract
Stimulate insulin release
Not in blood
Parasympathetic stimulation
Obesity
Sulfonylurea drugs
Suppression
Decreased blood glucose
Fasting
Somatostatin
Leptin
Synthesized as preproinsulin
ER
Cleave into proinsulin
Golgi
Cleaved to form insulin + C peptide
Insulin
Plasma half-life: 6 minutes
Degraded by
insulinase
in liver
Can also degrade alpha-beta protein in Alzheimer's disease
A and B chains attached by disulfide bonds
Mechanism of Glucose-Induced Insulin Secretion
Glucose enter the Beta cell via GLUT-2 Transporters
Glucose stimulates the Krebs Cycle
Glucokinase catalyzes the conversion of Glucose to G6P (critical first step in the Krebs Cycle)
ATP displaces ADP from OPEN ATP-sensitive potassium channels
Bound ATP causes channels to close
Depolarization of cells
Voltage-gated Ca channels open
Influx of Ca
1 more item...