Endocrinology: Adrenal Glands Flashcards
the ____ is important in pregnancy, lies between the ___ and ____ in the fetus. Very thick and rich source of ______, where it is converted to estrogen in the _____
fetal adrenal zone
cortex and medulla
androgens
placenta
glucocorticoids are released from the _____ layer of the cortex
both the zona fasciculata and zona reticularis
mineralocorticoids are released from the ______
zona glomerulosa
sex hormones/androgens are released from the ____
zona reticularis and zona fasciculata
______ is a group of modified post-ganglionic sympathetic nerve cells
adrenal medulla
adrenal medulla is composed of ____ cells
chromaffin cells (nerve cells without axons)
the adrenal medulla releases ____ and ____
80% EPI and 20% NE
EPI and NE are derived from ______
tyrosine
EPI/NE have similar effects at _____ receptors
beta1
EPI more selective at _____
beta2
5 big effects of EPI
1) mediate the body responses to stress (fight or flight)
2) increase cardiac output, blood flow (selective vasodilation/vasoconstriction)
3) stimulates glycogen/fat breakdown = fuels
4) stimulate insulin/glucagon both
5) enhances airway/respiration and CNS alertness
EPI adjusts blood flow: selective vasodilation in _____ via ____ receptor, and vasoconstriction in ___, ____, and ___
muscle —- beta2
gut, skin, and kidney —- alpha 1 and alpha 2 (digestive organs)
NE more important in ______ situations
non-emergency (adrenal source during emergency, autonomic system source during non-emergency)
______ is an adrenomedullary dysfunction in which there is an overproduction of catecholamines (mainly NE). Describe the pathophysiology. What is a specific diagnostic test?
- pheochromocytoma
- chromaffin cells from the neural crest migrate during embryogenesis all over the body to form nerve tissues, and can form pockets of chromaffin cells acting like small adrenal medulla glands all over body.
- measuring the NE/EPI levels
_____ is symptom that has the most frequent occurrence in pheochromocytoma. Why?
HTN
NE is secreted more then EPI, thus more vasoconstriction effects that leads to HTN.
draw out the adrenal steroid biosynthesis - aldosterone
CHL — PREG —- PROG — 11 - deoxycorticosterone —- corticosterone —- aldosterone
draw out the adrenal steroid biosynthesis - cortisol
CHL — PREG —17-hydroxypreg —- 17-Hydroxyprogesterone —- deoxycortisol —– cortisol
draw out the adrenal steroid biosynthesis - testosterone and estradiol
CHL — PREG — 17 - HYDROXYPREG —- DEHYDROEPIANDROSTERONE (DHEA) —- ANDROSTENEDIONE —- TESTOSTERONE —– ESTRADIOL
____ is main compound in non-pregnant women
estradiol
____ is main compound in pregnant women
estriol
important enzyme that cleaves off side chain from testosterone to make estrogen
aromatase
____ is the rate limiting step in adrenal steroid biosynthesis
CHL —> Pregnenalone
what is the major control mechanism for each zone of the adrenal cortex?
Z. glomerulosa —> renin-angiotensin system
Z. fasciculata –> ACTH
Z. reticular –> ACTH
Theoretically: how could Z. fasciculata and Z. reticularis grow larger than Z. glomerulosa?
ACTH is trophic, so could influence growth of fasciculata and reticularis; whereas angiotensin is NOT trophic
how does cortisol travel in blood? bound vs unbound
10% free
75% on CBG (transcortin) and 15% on albumin
how does aldosterone travel in the blood?
40% free
10% on CBG (transcortin) and 50% on albumin
how does DHEA-sulfate travel in blood?
2% free
98% on albumin
what could lead to an increase in free steroid hormones in blood?
underproduction of plasma proteins by liver
OR over secretion of hormone
____ most active of secreted adrenal steroid hormones. WhY?
aldosterone bc is travels in blood 40% free (much higher level of unbound hormone than others)
what are the two methods of metabolism of adrenal steroids?
1) reduction of biological activity (reduction of steroid molecule)
2) conjugation with glucuronides/sulfates in order to increase polarity and water solubility to allow for renal excretion
DHEA travels in blood with sulfate (which increases its water solubility) why isn’t it excreted by kidneys in great amounts?
bc it travels 98% attached to albumin in blood
_____ receptor has greater affinity for NE than for EPI
alpha 1 and alpha 2
second messenger and general effects of alpha 1 receptor?
activates IP3, DAG, and calcium
EXCITATORY
FOUND ON MOST SYMPATHETIC TARGET TISSUES
second messenger and general effects of alpha 2 receptor?
inhibits cAMP
INHIBITORY
found in digestive organs
second messenger and general effects of beta1 receptor?
activates cAMP
EXCITATORY
found in heart
second messenger and general effects of beta2 receptor?
activates cAMP
INHIBITORY
found in smooth muscles of arterioles and bronchioles
