Lecture 11: Hypothalamic-Pituitary Relationships and Biofeedback Part 2 Flashcards
Where are the adrenal glands located?
Immediately above kidneys
What does the Zona glomerulosa secrete?
Aldosterone
What does the Zona fasciculata secrete?
Cortisol (main)
Androgens
What does the Zona reticularis secrete?
Androgens (main)
Cortisol
What does the adrenal medulla secrete?
Catecholamines (Epi and Norepi)
What are the actions of catecholamines?
Rapid responder to stress
What are the actions of cortisol?
Longer-acting stress response
- Immune Suppression
- Gluconeogenesis
- Protein catabolism
- Lipolysis
What are the actions of aldosterone?
Regulates salt and volume homeostasis
What is DHEAS a precursor of?
Androgens
What can promote the production of cortisol?
Physical stress
Emotional stress
Metabolic stress
Infection and inflammation
When are cortisol secretory rates high? low?
High: early morning
Low: late evening
What promotes the production of aldosterone?
Low Blood Pressure
Low Blood Volume
Decreased sodium concentration
Increased sodium concentration
What causes Cushing’s Syndrome?
Increased cortisol production by adrenal gland
What are some symptoms of Cushing’s Syndrome?
Truncal Obesity Moon Face Buffalo Hump Purple striae Hirsutism
What does the low-dose dexamethasone suppression test reveal?
Differentiates patients with Cushing Syndrome from patients who do not have it
*If there is no ACTH suppression –> positive for CS
What does the high-dose dexamethasone suppression test reveal?
Differentiates patients with Cushing Syndrome from Cushing Disease
What causes Cushing’s Disease?
Increased ACTH secreting by a pituitary tumor
How does the high-dose dexamethasone suppression test work?
If the dexamethasone decreases ACTH levels, then it is caused by a pituitary tumor.
If ACTH levels stay the same, then it is caused by an ectopic tumor.
What can happen with administration of exogenous glucocorticoids?
Atrophy adrenal cells that produce cortisol
What is the primary action of aldosterone?
Renal sodium reabsoprtion
How does aldosterone work?
Steroid hormone that promotes synthesis of new protein channels and pumps.
Channels inserted on lumen of nephron to reabsorb sodium and secrete potassium.
What is ACTH derived from?
POMC (pro-opiomelanocortin)
What can increased ACTH cause?
Increased melanin synthesis –> hyperpigmentation
Why would hyperpigmentation be seen in Addison’s Disease?
Addison’s Disease is marked by low cortisol and aldosterone. Therefore, more ACTH is produced to compensate and a “side effect” is hyperpigmentation.
What can be used to detect adrenal gland insufficiency?
Cosyntropin (synthetic ACTH)
What can cause Addison’s Disease?
Autoimmune Disease
Adrenal hemorrhage
Infections from TB or N. meningitidis
Tumor
How are adrenal insufficiencies treated?
Exogenous/synthetic cortisol and aldosterone hormones
What is Conn’s Syndrome?
Excessive production of aldosterone in adrenal cortex
What can cause secondary hyperaldosteronism?
Excessive renin secretion by juxtaglomerular cells in kidney
What happens if there is a 17 alpha enzyme deficiency?
Increase in mineralocorticoids (aldosterone)
Decrease in cortisol, sex hormones
What happens if there is a 21 beta enzyme deficiency?
Decrease in mineralocorticoids (aldosterone) and cortisol
Increase in sex hormone
What happens if there is a 11 beta enzyme deficiency?
Decrease in aldosterone and cortisol
Increase in sex hormones and DOC
What are symptoms of a pheochromocytoma?
Hypertension
Headaches
Palpitations
Sweating
What receptors are found on the adrenal medulla to secrete catecholamines?
Muscarinic cholinergic
What is the rate limiting step in catecholamine production?
Tyrosine –> DOPA
Which receptors respond better to Norepi than Epi?
alpha receptors and beta 3
Which receptors respond same to norepi and epi?
Beta 1
Which receptors respond better to Epi than Norepi?
Beta 2
