Module #3: Adrenal Cortex and Reproductive Hormones Flashcards
What is the role of the Adrenal Gland in the endocrine system?
Response to stress
Maintain water/salt equilibrium
Maintain BP
Sympathetic function = “extension of ANS”
What are the 2 regions of the adrenal gland?
Medulla
Cortex
What does the adrenal medulla do?
Release catecholamines –> epinephrine and norepinephrine
What does the adrenal cortex do?
Release aldosterone, cortisol, and dehydroepiandrosterone (DHEA)
What are the 3 layers of the adrenal cortex?
Zona glomerulosa = outer
Zona fasiculata = middle
Zona reticularis = inner
What does the zone glomerulosa do?
produce/secrete mineralcorticoids (ie aldosterone)
What does the zona fasiculata/zona reticularis do?
produce/secrete glucocorticoids (cortisol) and adrenal androgen (DHEA)
What is the first step of hormone synthesis in the adrenal cortex?
cholesterol –> pregnenolone
What is the enzyme that converts cholesterol to pregnenolone?
desmolase
What is the stimulus of the conversion of cholesterol to pregnenolone?
ACTH from anterior pituitary
What happens after cholesterol is converted to pregnenolone?
Pregnenolone can follow 3 pathways to form aldosterone, cortisol, or DHEA
will go to a different region to be converted to the different hormones (each region has specific enzymes for one of the pathways)
Which enzymes do the zona glomerulus (outer layer) contain?
enzymes to convert pregnenolone –> aldosterone
Which enzymes do the zona fasiculata (middle)/zona reticularis (inner) contain?
enzymes that will convert pregnenolone –> cortisol OR DHEA
What happens if there are deficiencies in the adrenal cortex enzymes?
Siginifcant adrenal pathology
How are adrenal cortex hormone production regulated?
Syntehsized @ rate of demand
NOT stored!
How do adrenal hormone levels fluctuate?
Follow Circadian Rhythm Pattern
What are the adrenal hormone stimulus signaling steps (start w/ hypothalamus)?
Hypothalamus releases CRH
CRH stimulates anterior pituitary to release ACTH
ACTH stimulates desmolase activity (cholesterol –> pregnenolone)
What is aldosterone influenced by?
Angiotensin II
ECF (extracellular fluid) K+ levels
What inhibits adrenal cortex hormone production?
Increased levels of cortisol inhibits release of ACTH and CRH = negative feed back loop
Where are glucocorticoids (cortisol) produced?
Zona Fasiculata
Zona Reticularis
What stimulates cortisol secretion?
ACTH from anterior pituitary
Normal Circadian Rhythm
Stress
What is the normal circadian rhythm of cortisol release?
Released between midnight and 8 am –> peak just before awakening
How does stress stimulate the release of cortisol?
Stimulates the release of ACTH
Alter normal circadian rhythm
What inhibits cortisol secretion?
Elevated levels of cortisol inhibits ACTH and CRH