3.3 Flashcards
There are 6 hormones released from the hypothalamus: what are they?
GnRH, CRH, TRH, GHRH, Somatostatin, and Dopamine
What kind of hormones are Somatostatin and Dopamine? What are the others?
(not necessarily important in this lecture…but overall)
Somatostatin and Dopamine are INHIBITORY hormones
All the others are RELEASING hormones…they end in RH…not that complicated
What are the three types of hormones?
Protein
Steroid
Amine
What concentration of a hormone is necessary to illicit an effect?
Very small…nano–>pico
What is the role of carrier proteins in hormone transport?
Protect from being broken down in liver/kidneys
What happens in the POSTERIOR pituitary?
Oxytocin and vasopressin (from hypothalamic neurons) are immediately released to general circulation
Why are hormones from the hypothalamus released so that they will effect the ANTERIOR pituitary?
The hypothalamo-hyophyseal portal system bathes the anterior pituitary
What is the primary form of hormone regulation?
Negative feedback
Where is positive feed back seen with hormones?
Ovarian estrogen effects on ovulation
Is hormone secretion constant throughout the day?
No…it is sinusoidal or pulsatile
There is a circadian rhythm component as well
If it is constant-ish than it is a sick system
Where do preprohormones become prohormones? (protein hormones)
Preprohormones become prohormones in the RER
Where do hormones become fully matured? How is this done? What happens afterwards? (protein hormones)
Hormones are matured in the Golgi apparatus by further cleaving
The Golgi packages the mature hormones into secretory granules
Steroid hormones are synthesized from cholesterol…this is well known: where are the enzymes that form the final products?
Enzymes in the mitochondria and SER synthesize steroid hormones from cholesterol
Are steroid hormones stored?
No…steroid hormones traverse cell membranes down their concentration gradients
What form are most steroid hormones in in the serum? What is the form needed to act on target cells?
Steroid hormones are protein bound 99.9% of the time
The free hormone is able to enter cells
What are the two categories of amine hormones discussed in this lecture? (shitty question I know, but I wanted to point out that these were AMINE hormones)
Catecholamines (AMINE is even in the name…)
Thyroid hormones
Are catecholamines more similar to protein hormones or steroid hormones?
Catecholamines have properties similar to protein hormones
What is a property of catecholamines that is similar to protein hormones?
Packaged in vesicles and released intermittently upon demand…like insulin
Where are catecholamines produced?
Neurons
(this was the answer from this particular lecture…but NE/Epi often from chromaffin cells in adrenal medulla and DA is from substantia nigra and ventral tegmental area)
Do thyroid hormones behave more like protein hormones or steroid hormones?
Thyroid hormones act more like steroids
What property do thyroid hormones share with steroid hormones?
Thyroid hormone secretion involves diffusion down concentration gradient
What receptors do thyroid hormones bind to?
Thyroid hormones bind to receptors of the nuclear receptor superfamily
What are thyroid hormones synthesized on? Where are they matured?
Thyroid hormones are synthesized on a protein backbone and then processed in lysosomes
What regulates thyroid hormone synthesis?
Thyroid hormone production is controlled by enzymatic activity and iodine availability
Also similar to steroid hormones, except iodine instead of cholesterol
Hormones can kind of self regulate via negative/positive feedback, how else can hormones modify hormonal effects?
Down-regulate receptor signaling (decrease # of receptors or decrease receptor’s affinity for hormone)
Up-regulate receptor signaling (opposite of above)
Protein/peptide hormones are not lipid soluble and bind to membrane receptors: what are the two most likely types of receptors? What are the effects of hormone binding?
Protein/peptide hormones bind to tyrosine kinase receptors or GPCR
Binding to these receptors causes a magnified secondary messenger cascade
There are two major classes in the nuclear receptor superfamily (at least that’s what it looks like from this pwr pt.): what are they?
Steroid hormone receptors
RXR hormone receptors
What ligands bind to steroid hormone receptors?
Estrogen Progesterones Androgens Glucocorticoids Mineralcorticoids
What is needed for steroid hormones to illicit a transcriptional response?
Hormone:receptor homodimers must form
What ligands bind to RXR hormone receptors?
Thyroid hormones (receptor is T3R)
Vitamin D
Fatty acids, eicosanoids…PGs
What is needed for RXR hormones to illicit a transcriptional response?
Hormone:receptor + retinoid:RXR heterodimer must form
Example: (Vitamin D:VDR):(retinoid:RXR)
Which of the nuclear receptor superfamily receptors are important drug targets?
T3R (thyroid supplementation) GR (glucocorticoid therapies) PPAR (DMII treatment?) VDR (Vitamin D responses) PGR (progesterone therapy during pregnancy)
What are the possible fates of hormones?
Oxidation via P450s in the liver
Urinary/biliary excretion
Cell uptake and degradation following receptor signaling
