Endocrinology Overview Flashcards
True/False: Most cells have only one type of receptor for one hormone
false, most cells have multiple receptors which can be targets for multiple hormones
True/False: receptors on cell surfaces are hormone specific
False, hormone receptors of most cells can be targets for multiple hormones
True/False: most hormones affect multiple types of tissues
true
Which regulation of hormone secretion if more physiologically important?
feedback mechanisms, mainly negative
What is one of the few examples of positive feedback hormone regulation?
estrogen secretion preceding ovulation
testosterone negative feedback on the anterior pituitary and hypothalamus is a ____ loop example of negative feedback
long loop
What is an example of a short loop negative feedback
anterior pituitary on hypothalamus secretion
Describe the BASIC method of action/properties of peptide and protein hormones
water soluble, so must bind to cell membranes to exert their effects
Describe the BASIC method of action/properties of steroid and fatty acid compounds
lipid soluble so can diffuse across cell membranes so primarily bind to intracellular receptors
True/False: peptide/protein hormones are stored in secretory vesicles and once stimulation occurs their contents are released into extracellular fluid via Ca2+ mediated exocytosis
True
What is the foundational molecule for ALL steroid hormones
cholesterol
Why do steroid hormones have a slower response time than peptide/protein hormones
because they are synthesized on demand, they are not stored in secretory vesicles
What two major hormones are synthesized from tyrosine?
thyroid hormone and catecholamines
What two major hormones are synthesized from tryptophan
melatonin and serotonin
What is the primary role of eicosenoids?
they are lipid soluble local signaling molecules
What are eicosenoids synthesized from?
Fatty acids, primarily arachidonic acid
aspirin and NSAIDS inhibit which eicosinoid pathway?
COX
an inflammatory response will stimulate what enzyme in the eicosenoid synthesis pathway?
Phospholipase A2
Transport proteins are primarily synthesized in what organ
the liver
What type of hormone must be bound to circulate in blood
lipid soluble hormones
True/false: both bound and unbound proteins are biologically active
false, only unbound
What transport protein is hormone non specific?
ALB
What do CBG, DBG, TBG, and SHBG transport respectively
adrenocrotical hormones, Vit D metabolites, Thyroid hormones, sex hormones
What are the three main functions of transport hormones
- serves as a reservoir of hormones to draw from what needed
- stabilize free hormone levels
- Increase the lifespan of hormones int he blood
True/False: bound hormones can participate in feedback mechanisms
false, only unbound are biologically active and participate in feedback mechanism s
Describe the route of metabolism/elimination of peptide hormones and catecholamines
-free in circulation, so available for enzymatic degradation and excretion in bile
-After binding to receptors, target cells internalize the bound hormone and degrade intracellularly
Describe the route of metabolism/elimination of lipid soluble hormones
broken down inside target cells after binding to receptors
Describe the route of metabolism/elimination of steroid hormones/ thyroid hormones
Converted to water soluble compounds in the liver by glucuronidating, then re enter circulation and eliminated by kidneys
How can you change a cells response to a hormone
change the number of receptors on the target cell or the affinity of those receptors
How would you up regulate hormone response of a cell
increased synthesis or decreased degradation of receptors
How would you down regulate hormone response of a cell
receptors can be degraded or inactivated
What are the 5 mechanisms of hormone action
1.cAMP
2.IP3/Ca2+
3. Steroid hormone mechanism
4. Tyrosine kinase mechanism
5. cGMP
