1_IntroToEndocrinology Flashcards
How is NE synthesized
from Tyrosine
How is epinephrine synthesized?
Norepi + SAM via phenylethanolamine-N-methyltransferase
Which catecholamine is primarily a neurotransmitter?
NE
Describe the action of an autocrine factor?
acts on the same cell type nearby
Describe the action of a paracrine factor.
acts on many nearby cell types
Describe the action of an intracrine factor.
acts inside the same cell, but also in a minor fashion through paracrine or endocrine mechanisms. Linked to nuclear receptors.
what molecules act as intracrine factors?
intermediate metabolites, FFAs, oxysterols, retinoids, phospholipids
what is the structure of arachidonic acid?
20:4 (delta)5,8,11,14
what is the structure of linoleic acid?
18:2 (delta)9,12
describe the pharmacokinetics of eicosanoids.
short half-life; metabolized in lung and surrounding tissues
What molecules fall in the eicosanoid category?
PGE2, TX, PGI2, leukotrienes, lipoxins, PGE1
What is the major function of the eicosanoids?
local regulation of blood flow
How are cytokines classified?
by structure and by function
What is the function of the type 1 cytokines?
innate immune response
What is the function of the type 2 cytokines?
acquired immune response
What are the 4 structural classes of cytokines?
1) 4 alpha-helix bundle: IL2, IL10, interferon; 2) IL-1, 3) IL-17; 4) chemokines (NCP-1)
What are cytokines?
soluble peptides/glycoproteins secreted to act distally
What factors are secreted in an autocrine or paracrine fashion?
eicosanoids, cytokines, adipokines
What are the functions of miRNA?
mRNA target cleavage; translational repression; mRNA deadenylation
How are miRNAs released into the blood?
protein complexes; apoptotic bodies; exosomes
What are the types of hormones?
1) intracrine; 2) autocrine/paracrine, 3) endocrine; 4) neuroendocrine; 5) miRNA
How are hormone concentrations regulated?
1) secretion; 2) transport; 3) clearance
Describe the relative half-lives of peptides, catecholamines, and steroids.
catecholamines = seconds; peptides = minutes-days; steroids = hours
How are hormones cleared?
binding, catabolism, excretion
What is a diurnal rhythm?
daily
what is an infradian rhythm?
longer & more varied than diurnal
What hormones function on diurnal rhythms?
cortisol, androstenedione, DHEA; all are higher in the morning
What processes function on infradian rhythms?
menstruation, breeding, seasonal rhythms
How can hormone catabolism be prevented?
point mutations
What are examples of adipokines?
leptin, adiponectin, TNF-alpha, PAI-1, RBP-4
What are the functions of adipokines?
appetite control and inflammation
What did Arnold Berthold do?
“ablation and replacement” of roosters testes to evaluate sex behavior
What is the function of a signal sequence, and on which type of molecule is it located?
the first AA sequence which allows pre-prohormoneof a peptide hormone entry into rough ER during translation
How are peptide hormones generally secreted?
as the prohormone
What are the classes of hormones?
protein/peptide, steroid, tyrosine derivatives
What is the precurose for steroid hormones?
cholesterol
What is the rate-limiting step in steroid synthesis?
cholesterol via CYP450scc to pregnenolone
What is T4?
thyroxine
What is T3?
3,5,3’-triiodothyronine
What are the precursors for eicosanoids?
arachidonic & linoleic acids
Describe the relative storage characteristics between the 3 classes of hormones?
peptides (most)»_space; catecholamines»_space; steroids
Which classes of hormones are bound in the plasma?
steroids (90%) and the peptides CRH & GH
Which classes of hormones are free in the plasma?
peptides and catecholamines
On what order of concentration are the hormones in the plasma?
ng/mL or pg/mL
