chapter 7 Flashcards
what are exocrine glands?
- secrete their products into ducts
what are endocrine glands?
- secrete their products into the bloodstream
what is paracrine signaling?
- occurs when a cell secretes a signalling molecule that acts on nearby cells, and is heavily envolved in differentiation in embryonic development
what is autocrine signaling?
- when a cell releases a molecule that acts on itself, and is thought to play a role in the development of cancer
what is juxtacrine signalling?
- signalling that requires cells to be in close contact with eachother, even more local than paracrine
if a cell releases its secretions through exocytosis, it is known as a?
- merocrine cell
what are aprocrine cells?
- release their secretions through membrane-bound vesicles
what is holocrine secretion?
- results from rupture of the plasma membrane, destroying the cell and releasing its product from the cytoplasm into the lumen
hormones can be classified according to their chemical structure as?
- peptide hormones (composed of polypeptide chain)
- steroid hormones (desrivatives of cholesterol, and have characteristic 4 ring structure)
- amino acid derivatives
how do peptide hormones work?
- hydrophilic so they diffuse freely through the blood and exert their effects through receptors embedded on the outer surface of the p.m. which then change their conformation to produce an effect, often through a second messenger
- often associated with rapid, short-term changes in physiological function
how do steroid hormones work?
- not solube in the bloodstream so they require transport protiens to reach their targets which they then diffuse through the lipid bilayer and enter the cell where they bind with nuclear receptors that undergo conformational change and is translocated into the nucleus which then binds to DNA and affects gene transcription
- associated with slower onset and longer lasting physiological effects
peptide hormones are produced in stages:
- preprohormones (early precursors that are transferred to the rough ER and modified)
- prohormones (inactive precursors of hormones and processed in the Golgi apparatus where they are cleaved into the final hormone)
- hormones (packaged into vesicles and released through exocytosis)
what are the stages of a steroid hormone?
- synthesized from cholesterol in the smooth ER and diffuse directly through the cell membrane
what are amino acid derived hormones?
- small hormones derived form individual amino acids
- ex. thyroid hormones are tyrosine derivatives that are lipid-soluble and behave like steroid hormones
- ex. epinepherine and norepinepherine are also desrived from tyrosine but are water-soluble and act similarly to peptide hormones
- melatonin is both lipid and water soluble and is derived from tryptophan
how are hormones often regulated?
- negative feedback loops
- ex. hypothalamus-anterior-pituitary-adrenal cortex axis (HPA)
what is neuronendocrinology?
- refers to the fact that the nervous system and endocrine system “talk to” each other
details of insulin?
- function: glucose levels
- structural type: peptide
- stimulus: high glucose
- effect: low glucose
- location of secretion: pancreas (beta cells)
details of glucagon?
function: glucose levels
structural type: peptide
stimulus: low glucose
effect: raise glucose levels
location of secretion: peancrease (alpha cells)
details of cortisol (1)?
function: glucose levels
structural type: steroid
stimulus: stress
effect: raise glucose
location of secretion: adrenal cortex
