endocrine system Flashcards
what is endocrine communication?
a communication system using hormones as signalling molecules
what is a hormone ?
molecules releases by a gland into the blood to carry a signal to target tissue
what are the 2 types of hormone?
protein and steroid
describe the protein hormone
not soluble in membrane, so therefore binds to plasma membrane onto a complementary site and causes a release of secondary messenger inside the cell
describe the steroid hormone
is lipid soluble so can pass through the membrane so can have a direct effect on target
why are steroid hormones lipid soluble ?
synthesised from lipid-based molecules like cholesterol so soluble in fats and dissolve in the lipid bilayer
what is an endocrine gland?
ductless group of cells that secreates hormone straight into the bloodstream
what is an exocrine gland?
group of cells around a small duct that secrete products into the duct leading to the site requiring the substance
why do hormones have specific targets ?
to produce a specific response in specific places
why is each hormone different?
so it doesn’t react to everything whilst travelling around the body and only reacts with the target cells
what is a first messenger ?
non-steroid hormone - causes release of secondary
explain the path of a non steroid hormone binding to target cell
binds to plasma membrane- activates G protein- which activates an effector molecule - which converts ATP to cyclic AMP which is the secondary messenger- this will act on another protein to activate enzyme controlled reactions to alter cell activity
where is adrenal gland found?
anterior to kidneys
why do the adrenal glands have a good blood supply ?
hormones travel in the blood so their transport network needs to be available near the production site
name the outermost layer of the adrenal cortex
zona glomerulosa
name the middle layer of the adrenal cortex
zona fasciculata
name the innermost layer of the adrenal cortex
zona reticularis
state what the zona glomerulosa secretes
mineralocorticoids - aldosterone