L2 Flashcards
what do steroid receptors do?
alter gene expression - change the proteins the cell makes or change what they do
what does an ion channel do?
changes membrane conductance - changes the ability of ions to move across the membrane
what does a G-protein coupled receptor do?
alters protein activity
what does a cytokine receptor do?
regulates many cellular events
what are steroids?
molecules chemically based on modifications of cholesterol
cortisol is a steroid. where is it produced?
adrenal cortex
aldosterone is a steroid. where is it produced?
adrenal cortex
progesterone and estradiol are female sex hormones (steroids). where are they produced?
ovaries
testosterone and dihydrotesterone are male sex hormones (steroids). where are they produced?
testes
what are neurosteroids made by?
neurons and glial cells
what is cortisol released in response to?
stress
what is aldosterone produced in response to?
fall in blood pressure
what steroid are neurosteroids based on?
pregnenolone
where do neurosteroids act?
brain
are steroids hydrophobic and lipophilic or hydrophilic and lipophobic?
hydrophobic and lipophilic
why are lipophilic hormones synthesised on demand?
because they cannot be stored
how do lipophilic hormones leave the steroid releasing cell?
diffusion
how do lipophilic hormones act on the receptors? what kind of receptor and how does it interact with the cell
crosses cell membrane and acts on intracellular receptors
why are all cells exposed to a lipophilic hormone when released into the blood?
because it’s in the blood which goes everywhere and can interact with cells as it is lipophilic
what two hormones does stress cause the release of? where from?
cortisol and adrenaline from adrenal gland
what are 3 differences between cortisol and adrenaline’s effects, increase in blood and elevation?
- increase in cortisol concentration in blood is slower than adrenaline
- cortisol remains elevated for longer
- cortisol’s effects on target tissues are more prolonged
what is the first step of cortisol release?
adrenal cortical cells activated by ACTH via MC2 receptor (ACTH receptor)
what occurs after the adrenal cortical cells are activated?
the G-protein coupled receptor is activated
what does the activated G-protein coupled receptor do?
increases cAMP
what does the increase in cAMP stimulate?
protein kinase A (PKA)
what does PKA activate?
transcription factors
what does the the stimulation of PKA increase?
increases expression of cortisol synthesising enzymes
