General Physiology Flashcards
Describe the difference between endocrine hormones, paracrines, autocrines, and cytokines
Endocrine hormones - released into circulation to act on target organ somewhere else
Paracrines - released hormones to act on neighboring cells
Autocrines - act on same cells
Cytokines - can act as paracrines, autocrines or circulating hormones
What are the 3 classes of proteins?
- peptides and proteins
- steroid hormones (cortisol, aldosterone)
- tyrosine hormones (thyroid hormones, epinephrine/norepi)
What is the difference between polypeptides and proteins?
Both made of AAs, polypeptides up to 100 AA, >100 are proteins
Describe the production/synthesis of polypeptides and protein hormones
Produced by the endoplasmic reticulum—> Golgi apparatus to be placed into vesicles —> vesicles either released by exocytosis to release hormones or stored under cell surface for later release
Describe the synthesis of steroid hormones. How are these stored?
Synthesized from cholesterol
very little storage of steroids –> but store cholesterol –> can be used for synthesis fast
fat soluble
In what two places/organs are hormones derived from tyrosine produced?
- thyroid gland
- adrenal medulla
What is thyroglobulin?
macromolecule that is used to bind and store thyroid hormones in the thyroid gland
What plasma protein carries thyroid hormones?
thyroxine-binding globulin
What is the normal ratio of epinephrine to norepinephrine secretion from the adrenal medulla?
4 to 1
Name 2 water-soluble hormones
adrenaline
growth hormone
groups: catecholamines and peptides are water soluble
dissolve in plasma and freely “swim” to target tissue
Name 2 protein-bound hormone types
thyroid hormones, steroids
need to be protein-boudn to be transported to target tissues –> once at target tissues need to dissociate from the protein to become active and move into tissue
What are 4 ways of metabolic clearance of plasma hormones?
- hepatic excretion into bile
- renal clearance
- metabolism by tissues
- binding with tissues
How are steroid hormones mainly cleared?
conjugated into the bile by the liver
liver failure –> excessive plasma steroid hormone levels
How are catecholamines and peptide hormones cleared?
degraded by tissue enzymes and then excreted by liver and kidneys
Where are receptors located for:
* catecholamines and peptides, proteins
* steroid hormones
* thyroid hormones
catecholamines/peptides - cell membrane
steroid hormones - cytoplasm
thyroid hormones - nucleus