10/7 Edocrine gland histology Flashcards
what are the plus/minus of synaptic signaling?
fast, local, signal reception and termination is to guaranteed geography;
expensive energetically to set up and maintain
what are the plus/minus of the endocrine signaling
Cheap energetically, geography is widespread
slow, signal reception and termination is not guaranteed,
What is endocrine feedback
links signal production to response and hopefully regulates the response.
what type of feedback is it when the product generated inhibits the signal generating the product?
negative feedback
what is a famous example of positive feedback?
hypothalamus/pituitary release of LH to ovary which releases estradiol, which stimulates release of LH
what is the difference in signal and product feedback
product feedback is from the product to higher up in the chain to a cell that didn’t produce the signal. signal feedback is to the same cell that excreted the signal.
why would you want some signal feedback
to give immediate and direct feedback to the producing cell, and lead to tighter control.
why would complex systems be used in the body
they see to be more stable, where a chain of signals give rise to a product where each step has product and signal feedback
general features of endocrine glands
ductless
specificity conferred by receptors on target cells
predominantly parenchyma ;little stroma
abundant blood supply, glands often contain fenestrated capillaries
typically, each cell is adjacent to capillary or lymph vessels
features of protein and polypeptide hormones
hydrophilic synthesized on RER stored in granules bind to receptors on cell membrane activate second messenger systems
properteis of steroid derivatives
hydrophobic synthesized on SER, not stored diffuse through cell membrane bind to cytoplasmic receptors act as transcription factors
properties of the tyrosine and phenylalanine derivatives (mixed)
mixed hydrophobic/philic
thyroxien is hydrophobic and binds to cytoplasmic receptors, acts as a transcription factor
epinephrine adrenalin binds to G-protein coupled cell surface receptors.
exmp. of protein and polypeptide homones
insulin, glucagon
exmp. of steroid derivitive hormones
progesterone, estradiol, testosterone, cortisol
what is the gland that links the endocrine and nervous systems
the pituitary or the hypophysis (same thing)
where is the pituitary?
in the base of the brain!
describe the structure of the pituitary
hypothalamus, connected by the stalk and portal vessels to the anterior pituitary with the posterior pituitary behind that.
anterior pituitary other name
pars distalis or the adenohypophysis or pars anterior
posterior pituitary other name
pars nervosa or the neurohypophysis
what is the feedback molecule for adrenal back to the pituitary?
cortisol is the feedback to the pituitary!
what is the difference in synaptic and endocrine signaling
synapis: use a junction with close or direct contact with ion channels (neurons) etc. used by the nervous and immune system. used for behavior control
Endocrine is diffuse secretion with G-protein coupled, enzyme coupled, intracellular receptors, used by pretty much everything used for homeostatsis control
the stalk between the hypothalmus and anterior pituitary
Pars tuberalis that surrounds infundibulum