lec 11. cell communication Flashcards
adrenaline
produced by adrenal glands, acts on adrenergic receptors to produce fight or flight response
bisoprolol
B1 adrenergic blocker in heart so that it is less sensitive to adrenaline, but rest of body responds
endocrine signalling
cells produce hormones that travel in the bloodstream to other cells that have to have receptors specific to respond to that hormone
synaptic signalling
small group of cell in the nervous system talk to and exchange information - they have a PHYSICAL link
steroid hormones
steroids that act as hormones. they are synthesised from cholesterol and have both hydrophobic and hydrophilic properties
cholesterol
a lipid that makes up 30% of all cell membranes via a 37 step pathway
classes of steroid hormones and examples
corticosteroids made in adrenal gland (glucocorticoids, mineralocorticoids)
sex steroid made in gonads and placenta (androgens, estrogen, progestrogens)
steroid receptor + its domains
respond to steroid hormones. if they are nuclear, they act as transcription factors
n-terminal (facilitates gene expresson), DNA binding domain, hinge region, ligand binding domain, c-terminal
function of active steroid receptor
ligand binding causes a conformational change so that COOH locks ligand in and DNA binding domain binds to DNA and transcribes target gene (primary response protein + secondary response protein)
dexamethasone
a glucocorticoid (similar to cortisol) that binds to glucocorticoid receptors and expressed genes which regulate metabolism
how cortisol is produced
hypothalamus produces corticotropin-releasing hormone -> pituitary releases adrenocorticotropic hormone (ACTH) -> adrenals make cortisol
Addison’s disease
too little cortisol due to damage to adrenal glands (primary) or to pituitary (secondary)
symptoms: depression, flu-like, weight loss
cushings syndrome
too much cortisol caused by benign adenoma which produces too much ACTH, or by long term steroid use
symptoms: weight gain, increase blood pressure, puffy face, hair growth
insulin
made by beta cells in pancreas in response to increased blood glucose and causes liver, muscle, and fat cells to take up glucose
also induces glycolysis, glycogenesis, and lipogenesis
molecular basis of insulin signalling pathway
binding of insulin moves intracellular kinase domains closer -> phosphorylates tyrosine (on insulin receptor (IR) and insulin receptor substrate 1 (IRS1)) which allow binding of the lipid kinase PI3K which synthesizes PIP3 -> recruits phosphoinositide-dependent kinase (PDK) -> directly phosphorylates the Thr308 residue of AKT -> Activated AKT phosphorylates substrates at Ser/Thr residues -> effectors involved in glucose uptake, lipid & protein synthesis.
