ACTH (adrenocorticotropic hormone) is released from the

pituitary and binds to cell surface receptors on the adrenal cortex. Uses the

second messenger system -

phosphorylates a protein and enzymes that allows cholesterol to be released. The cholesterol is broken down by

to produce cortisol, which is a

steroid hormone.

One hormone binds to the receptor, releasing

from the receptor.

is activated and the second messenger produced.

When a hormone binds,

is activated. Most of the time, two hormones need to bind at the same time - called

Hormone binds to a specific receptor which is attached to a

The G protein is released and binds to

which converts ATP into cAMP (gains a cyclase and loses 2 phosphates) - the 2nd messenger. cAMP activates

which phosphorylates proteins etc.

Hormone binds to specific receptor which is coupled to

Binding releases the G protein, which then binds to

(cleaves lipids). This cleaves PIP2 into IP3 and

the latter of which activates

IP3 opens calcium ligand channels on ER, so calcium moves into the cytosol and intracellular calcium increases, which triggers responses

Steroid hormones are all derived from

which is broken dowin to pregnenolone, catalysed by

That is then broken down to progesterone, then either to androgens (e.g. testosterone), glucocorticoids (cortisol), or

(aldosterone). The type of steroid produced depends on the

available in the cell.