ENDO- Hormones Flashcards
where are neurotransmitters released from?
axon terminals of neurons into the synaptic junctions and act locally to control nerve cell function
Which neural signaling requires no contact, last hrs-days, target is distant?
endocrine hormones
Dispersed anatomy
released by glands or specialized cells into the circulating blood and influence the function of target cells
Which neural signaling requires contact, fast, target is near?
neuroendocrine
secreted by neurons into the circulating blood and influence the function of target cells at another location in the body (posterior pituitary)
Describe paracrine signaling
A cell uses a hormone signaling mechanism to signal a nearby cell
Describe autocrine signaling
Cell releases a substance that turns around to signal/act on the same cell
Describe cytokines
peptides secreted by cells into the extracellular fluid and can function as autocrine, paracrine or endocrine hormones, ex interleukins, adiopkines
WHich system needs a Chemical nature of signal?
Both systems need chemical mediators
Describe how the nervous system and endocrine system differ in anatomy
Nervous system is interconnected;
Endocrine is more dispersed since chemical mediators are released in the blood
Define a hormone
signaling molecule (chemical signal) released by signaling cell that stimulates effect from target receptor (usually glandular) that exists at a distance, Usually really small amounts circulating with narrow normal ranges
What are the 3 forms of hormones?
1] steroids, 2] derivatives of tyrosine, 3] proteins or peptides
What is the difference between peptides and proteins
< 100 amino acids is a peptide hormone,
>100 amino acids it’s a protein hormone.
List the derivatives of tyrosine
thyroxine and epinephrine (adrenalin)
Which moleucule has a small molecule with carbon ring and 6 double bonds; small active group
Tyrosine
Describe Thyroxine (T4)
2 tyrosine rings and iodines; and if you add a 2nd and 3rd hydroxyl group you make epinephrine
TWO DITs
Describe the difference in structure between peptides ADH and Oxytocin
ADH has PHE and ARG, 2 diff
both very similar in structure and both have sulfide bonds
Describe steroid hormones
4 carbon ring
nonpolar, easier to get through cell membrane
example is progesterone
Where is the production of protein/peptide hormones?
formed in RER rough endoplasmic reticulum
protein processing here
Where is location of production of Tyrosine?
cytoplasm
What is important in control of secretion of hormones?
secretion is controlled by negative feedback, the amount of the hormone in the blood or secreted, IS NOT important, but the ACTIVITY of the hormone that causes an effect.
What are the action of hormones once binded?
All act through receptors,
INDIRECT Chemical cascades provide amplification of signal
when hormone binds to receptor, some have a direct effect and a indirect effect
Stimulates nucleus to make 10k messegers
Describe the direct and indirect effect
direct effect is on intracellular enzyme
indirect effect is a cascade of enzymatic activity that leads to secondary signaling molecules
List the locations of hormone receptors
1] In or on the surface of the cell membrane (peptides or proteins)
2] In the cell cytoplasm (steroid)
3] In the cell nucleus (thyroid)
Describe the cAMP signaling and what is the most well know hormone receptor.
1] hormone binds causing the G protein to release GDP and bind GTP instead,
2] G-protein subunits separate and binds to adenylyl cyclase via phosphorlation.
3] this catalyzes the conversion of cAMP inside the cell,
4] leads to action of the cell
GTP main receptor
Describe the cAMP signaling using ADH as an example
ADH in renal cells act through 2nd messenger
stimulating adenyl cyclase converting cAMP and
then cAMP acts to phosphorylate other molecules Kinase
and enzymes within the tubular cell to result in insertion of aquaporins
