Physiology 17: hormone signaling and feedback control

hormone signaling steps

1. synthesis
2. release
3. transport
4. recognition
5. signal transduction
6. removal

type of hormone determines...

which receptor and biological effect

proteins are synthesized are

peptide/protein and steroid

peptide/protein synthesis

in DNA where ribosome contain preprohormone and change in ER to prohormone

steroid hormone synthesis

cholesterol to a variety of hormones

transport of hormone by secreting cell is done by

endocrine, paracrine, and autocrine

steroid receptor recognition

acts in DNA to change gene activity and bind to receptor and initiates trascription/translation

protein receptor mechanism

needs a 2nd messenger with G-coupled and tyrosine kinase

G-coupled receptor types

adenylate cyclase and phospholipase C

adenylate cycle enzymes

bind to receptor, adenyl cycle triggers 2nd messenger

phospholipase C enzyme

protein bind to receptor and activate phospholipase C, 2nd messenger cascade initiated

tyrosine kinase proteins

single untis dimerize and 2nd messenger cascade begins

signal transduction

within target cell triggered by hormone-receptor complex resulting in change in cellular metabolism, function, and development

types of signal transduction

short or long lasting

short lasting transduction

fast, stored in secetory vesicles, affects protein kinase cascade, terminated by blood degradation and tissue proteases, peptide

long-lasting transduction

slow, made on demand, converted from precursor, transported by carrier proteins, steroid

feedback loops

activation and inhibition

receptor activation

triggers feedback signal to shut off or is removed

upregulation

receptor activation triggers feedback signal increase is or affinity of receptor

hormone agonist

Binds to receptor, Similar conformation change as hormone, Mimics same action

hormone antagonist

Bind to receptor and interrupts, Blocks natural hormone, Bind to diff. places and affect diff. functions