Endocrinology Flashcards
What are peptide hormones
chains of amino acids
How are peptide hormones synthesized?
- Begin with an inactive prehormone (PrepoTRH)
2. A process will break that down to cleave 6 of the same hormone (6 TRH)
What is another way it can be synthesized
- Prohormone active on its own
- There is a process to cleave 3 types
ex: POMc is a active prohormone that suppresses apetite and weed inhibits it
How does secretion happen for a peptide
Vesicles exocytose in responce to a stimulus
How does circulation happen for peptide
- Dissolve in plasma mostly
What is half life
amount of time required to reduce the hormon concentration by half
What is the half life of a peptide
short! not around as long to exert effect
How are peptides metabolized?
degraded by peptidases (exopeptidase & endopeptidase)
Peptide hormones will act on …
membrane bound receptors
- Receptor-enzyme OR
- G-protein coupled receptor
Steroid hormones are derived from what?
cholesterol
Where are steroids synthesize, and secreted from? (3)
gonads, adrenal gland, placenta
WHat is the deal with steroid synthesis?
Cholesterol is present everywhere but specific enzymes are needed to turn cholestrol into a hormone. ex: CRH (from the hypothalamus) -> ACTH (anterior pituitary) -> activates an enzyme that will turn cholesterol into cortisol
WHy do men have less estrdiol if it is produced mostly from testosterone?
because they lack the enzyme to convert it
How are steroids secreted?
- Diffuse accross the membrane (at no point are they in the vesicle)
- Synthesized on demand as they cannot be stored
How are steroids transported?
By binding proteins
Where are steroids metabolized?
In the liver and excreted
Do they have a longer half life?
Yupperzzzzzzzzzz IM TIRED :(
Steroid receptors can be in?
Plasma & move to the nucleus or just be inthe nucleus
When a steroid and bunding complex arrives, what must it do?
dislodge
steroid hormones that bind on the surface have a much more
rapid responce ex: cortisol
What happens to the receptor hormone complex once inside the cell?
binds to DNA and activates or represses genes affecting mRNA and translation
Amines are all derives from?
tyrosine!!!!
How are catecholamines (E, NE, D) secretes? THINK NEURO & transported ((peptides))
Exocytosis & dissolve
HOW IS thyroid hormones secreted? (T4 & T3) and transported ((steroids))
trhough diffusion & carrier proteins
HOw do catecholmaines create action vs. thyroid hormones?
membrane bound vs. intracellualar
THe positerior pituitary is not really a gland its an
extention of the NS
Anterior pituitary is a true endocrine gland
True
What part of the aterior pituitary re;eases hormones?
pars distalis
If the pituitary enlarges anough it cen affect
vision by compressing the optic chiasm
The PVN and SN nuclei in the hypothalamus
produce 2 different hormones that extent to posteriror pituitary to release vasopressing and oxy tosin into the blood from a a capillary bed
What happens to oxytosin levels during pregnancy
THere is not a huge change in the blood, but an insane amount of receptors are produced which allowsoxytosin to bind very easily
Vasopressin is a
peptide
What does vassopressin do? (2)
enhances water retention from kidneys and contracts arteriole smooth muscles
How does synthesis in the anteriror pituitary work?
hormones from the hypothalamus act on endocrine cells in the anterior pituitary to release hormones
