Ch18 Flashcards
____system : -Nerve impulses/ Neurotransmitters -Faster responses, briefer effects, acts on specific target
Nervous
____ system: -Hormone-mediator molecule released in one part of the body but regulates activity of cells in other parts -Slower responses, effects last longer, broader influence
endocrine
ducted glands are..
exocrine (endocrine)
ductless glands that secrete products into interstitial fluid; diffuse into blood
endocrine gland
pituitary, thyroid, parathyroid, adrenal and pineal glands are all ____ glands
endocrine
Hypothalamus, thymus, pancreas, ovaries, testes, kidneys, stomach, liver, small intestine, skin, heart, adipose tissue, and placenta
exceptions : organs and tissues not exclusively endocrine
affect only specific target tissues with specific receptors in which constantly synthesize and break down -Down-regulation – decrease in receptors -Up-regulation – increase in receptors
hormones
regulation in endocrine system can be activated or inhibited by:
neural regulation, hormonal regulation, or humoral regulation
2 hormone types are
- Circulating – circulate in blood throughout body
- Local hormones – act locally
- Paracrine – act on neighboring cells
- Autocrine – act on the same cell that secreted them
lipid soluble -use transport proteins- hormones include
- steroid hormones
- thryoid hormones
- nitric oxide
water soluble hormones that circulate in free form include:
- amines
- peptides/proteins
- eicosanoids
- Water-soluble hormones bind to receptors on the plasma membrane and …
- Activate second messenger system
- Amplification of original small signal
Responsiveness of target cell depends on what 3 things
- Hormone’s concentration
- Abundance of target cell receptors
- Influence exerted by other hormones
- lipid soluble hormones binding to receptors inside target cells
mechanism of action of lipid soluble steroid and thyroid hormones
water soluble hormones bind to receptors on the plasma membrane ; then …
- activate second messenger system
- amplification of original small signal
responsiveness of target cell depends on …
- hormone’s concentration
- abundance of target cell receptors
- influence exerted by other hormones(permissive, synergistic and antagonistic effects)
- lipid soluble hormone diffuses into cell
- activated receptor hormone compelx alters gene expression
- newly formed mRNA directs synthesis of specific proteins on ribosomes
lipid soluble hormone action
- first messenger binds to its receptor activates G protein activating adenylate cyclase
- activated adenylate cyclase converts ATP to cAMP
- cAMP serves as 2nd messenger to activate protein kinases
- activated protein kinases phosphorylate cellular proteins
- millions of phosphorylated proteins cause reactions that produce physiological responses
water soluble hormone action
control of hormone secretion regulated by:
- signals from nervous system
- chemical changes in the blood
- other hormones
[most hormonal regulation by negative feedback]
major link btwn nervous and endocrine system
hypothalamus
- somatotrophs
- thyrotrophs
- gonadotrophs
- lactotrophs
- corticotrophs
ADENOHYPOPHYSIS cells
human growth hormone and insulin like growth factors are what type of anterior pituitary cells
somatotrophs