Endo - Intro Flashcards by Cristina Resczenski

endocrine characteristics

secreted by specialized endo cells into blood

travel long distances

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neuro-endocrine characteristics

product of neuron

released into blood

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neural characteristics

product of a neuron
secreted into synaptic spaces
travels short distances

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paracrine characteristics

secreted into extracellular space

diffuse short distances

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autocrine characteristics

hormone secreting cell same as receptor containing cell

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hormones : effects

usually more than one effect -
due to different target cells
or changes to effect based on developmental stage

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peptide/protein hormone characteristics

encoded by DNA
hydrophilic
receptors on cell surface
secondary messengers
can be stored
often circulate unbound

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amine hormone characteristics

tyrosine derivatives
hydrophilic
receptors on cell surface
secondary messengers
*exception T3/T4

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thyroid hormones characteristics not like amines

intracellular receptors

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steroid hormone characteristics

llipophilic (non-polar)
receptors in cytosol or nucleus
derived from CHL w/ cyclopentano... ring (no DNA)
not stored
bound to specific globulin in blood
long 1/2 lives

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cross talk

may happen among hormone families

diff hormones bind to the same receptor

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preprohormone actions

preprohormones are translated, partially then arrested by signal recognition complex that binds to signal peptides
the complex releases when it binds to a docking protein on the ER –> translation completes
–> prohormone

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prohormone actions

prohormone is cleaved into active hormone in golgi

or prohormone is secreted and converted to active in ECF

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active hormone secretion

packaged into secretory vesicles in golgi
await signal as membrane bound granules
exocytosed into blood stream

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peptide hormone Tx route

not orally (inactivated by acid in stomach or peptidases in intestines) 
usually injected

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groups of amine hormones

thyroid hormones

catecholamines

amine hormones from tyrosine

T3 = 2 tyrosine + 3 Is
T4 = 2 tyrosine + 4 Is
cats = modified tyrosines

catecholamine synthesis steps

tyrosine –> dopa –> dopamine –> NE –> E

catecholamine synthesis location

synthesis enzymes in cytosol

stored till secreted

types of steroid hormones

glucocorticoids
mineralcorticoids
vit D
androgens
estrogens
progestogens

steroid sythesis

many enzymatic steps (many disorders possible)

cells only have enzymes for specific steroid to be made

steroidogenic enzymes

side chain cleavage enzyme; desmolase
17 alpha-hydroxylase
21-hydroxylase
aromatase

steroid metabolism

metabolized by cytochrome P50 in liver
excreted in urine or bile
1/2 lives can be very long (esp synthetic)

route of steroid hormone Tx

can be given orally

eicosanoid characteristics

derived from fatty acids (usually arachadonic acid) released by lipases act locally - paracrine only active a few seconds (rapidly metabolized)

regulation of endocrine activity (broad)

rate of production* rate of delivery (ex. blood flow) rate of degradation (liver) and elimination (kidney)

chronotropic control

endogenous neuronal rhythm based on diff external things (light/dark, eating, temp) vary in time frame may be diff @ diff life stages

pacemaker of circadian rhythms

suprachiasmatic nucleus

importance of pulsatile hormone release

maintains secretion of necessary hormones | continuous would inhibit other things or block production (down regulation of receptors)

binding proteins and half life

binding delays metabolism provides reservoir of hormones greater affinity to bps --> greater half life

hormone receptor characteristics

specificity (only certain hormones) affinity (changed by conformation, down with high hormone levels) density (up or downregulation --> de/sensitization)

permissiveness

one hormone in adequate amounts necessary for full effect of other protein to happen

synergism

combined effect is greater than sum

antagonism

one hormone lessens another hormone's response

agonist

molecule binds to receptor induces receptor to biological effect (act like hormone - may be more or less potent)

antagonists

molecule binds to receptor blocks agonist from binding no biological effect occurs