5.1.4 Hormonal Communication Flashcards
what’s an endocrine gland?
group of cells specialised to secrete hormones directly into bloodstream, where they travel to and are detected by target cells
what is a hormone?
chemical messenger secreted directly into blood when a gland is stimulated that has an effect on target cells
what are the two types of hormone? (outline)
Steroid hormones
Non-steroid hormones
what’s an exocrine gland?
secretes chemicals through ducts into organs/surface of body
Steroid hormones
- lipid-soluble
- can pass directly through bilayer and bind to steroid hormone receptors in cell cytoplasm or in nucleus
- hormone-receptor complex acts as transcription factor which facilitates or inhibits transcription of particular genes
- eg. oestrogen
Non-steroid hormones
- hydrophilic so cannot pass through cell membrane so bind to specific receptors on csm of target cell
- trigger a cascade of reactions mediated by second messengers (cAMP)
- eg. adrenaline
hormonal vs neuronal communication
Hormonal
- communication by hormones
- transmission by blood
- transmission & response is slow
- hormones travel to all parts of body but only target cells respond
- response is widespread
- response is long-lasting
- effects may be permanent and irreversible
Neuronal
- communication is by nerve impulses
- transmission by neurones
- transmission and response is v rapid
- impulses travel to specific parts of body
- response is localised
- response is short-lived
- effect is temporary and reversible
what hormones does the adrenal cortex make?
hormones that are essential to life
long term stress response
production of hormones by adrenal cortex is controlled by hormones released by anterior pituitary gland.
Minteralocorticoids
- Aldosterone
- > stimulates H2O and Na+ to be reabsorbed from kidneys, increasing BP
Glucocorticoids
- Cortisol
- > regulates metabolism by controlling how body converts fats, proteins, and carbs to energy
- > increases BP in response to stress
- > suppresses immune system
Androgens
-> small amounts of male and female sex hormones eg. control libido in females
what hormones does the adrenal medulla make?
hormones that are non-essential
immediate stress response
production of hormones by adrenal medulla is stimulated by nerve impulses from sympathetic nervous system (hence acute stress response)
- Adrenaline
- > increases HR, sending blood quickly to muscles and brain
- > rapidly raises blood glucose levels by converting glycogen to glucose (glycogenolysis)
- Noradrenaline
- > works with adrenaline, increasing HR
- > widens pupils
- > widens air passages in lungs
- > narrows blood vessels to non-essential organs (hence increasing BP)
exocrine function of pancreas
produces digestive enzymes and pancreatic juice which are secreted into ducts and released into the duodenum via pancreatic duct
- pancreatic acini are ducts that lead to pancreatic duct
endocrine function of pancreas
produces insulin (B cells) and glucagon (a cells) - islets of langerhan are regions within endocrine tissue
what is a difference in appearance between alpha cells and beta cells
alpha cells are bigger and more numerous
you can use a differential stain to distinguish
