#31 Flashcards
(30 cards)
what is the most common class of hormone?
peptide hormones: chains of amino acids
Examples of peptide hormones
pituitary hormones, angiotensin, insulin, glucagon, IGF-1, PTH
Examples of amino acid hormones
epinephrine, thyroid hormones
examples of steroid hormones
adrenal cortical hormones, sex hormones
How are steroid and thyroid hormones transported?
carrier proteins in the blood
how are peptide hormones transported?
directly in the blood
How do steroid and thyroid hormones exert their effects on the cell?
Bind to nuclear receptors that bind to DNA and regulate gene transcription
Response is altered protein expression that results in a response
How do peptide hormones and catecholamines exert their effects?
bind to cell surface receptors
Receptor binding triggers signal transduction pathways that activate or deactivate enzymes, open channels, etc
Exocrine function of the pancreas
digestive enzymes
endocrine function of the pancreas
insulin and glucagon and somatostatin
Gluconeogenisis
making new glucose, primarily from lactate
glycogenisis
formation of new glycogen
glycogenolysis
breakdown of glycogen
glucagon secretion increases
gluconeogenisis, glycogenolysis, lipolysys, plasma fatty acids, ketogenisis, protein degradation
Glucagon signaling
g protein linked receptor, PKA phosphorylates other proteins
How does glucose enter the cell?
requires glucose transporters
plasma glucose increases
insulin secretion, glucose uptake into cells, glycogen synthesis, triglyceride synthesis, amino acid transport into cells, protein synthesis
how is insulin released? (7 steps)
- Glucose is in high concentration outside of the cells and moves in via facilitated diffusion (glut 2)
- Glucose is converted to pyruvate through glycolysis
- Oxidative phosphorylation occurs
- ATP acts as a ligand and closes ATP selective K+ channels, blocking K+ movement outside of the cell
- BLocked K causes depolarization
- Depolarization opens voltage gated Ca channels
- Calcium triggers release of insulin by exocytosis
Insulin mediated glucose uptake
insulin binds to receptor
Binds to IRS1 which eventually binds to AKT
AKT phosphorylates AS160, which then binds to 14-3-3 to innactivate it. When AS160 is active, it has a RABGAP domain that is a GTPase. When GTP binds to GLUT 4, RABGAP gtpase innactivates GLUT 4 by turning GTP to GDP. When GLUT 4 retains GDP it can bind to membrane and open
factors controlling insulin secretion
blood glucose concentrations, gastrointestinal hormones, blood amino acid concentration
why is excessive blood glucose so bad for you?
forms reactive oxygen species which damages pretty much everything in your body
Diabetes mellitus
elevated fasting blood glucose
type 1 diabetes
autoimmune destruction of B cells
Insulin deficiency
patient must take insulin
Type II diabetes
90% of diabetics
insulin resistance
insulin secretion compensates for insensitivity, then deficiency occurs in the later stages
