What is Cushing's disease?
A pituitary dependent hyperadrenocorticism (Usually the result of a pituitary tumor)
What are some of the main symptoms of Cushings-like syndrome (for dogs)?
Lethary & Obesity
There are 2 main functions of Aldosterone. What are they?
Conservation of Na+ (Which water follows)
Excretion of K+
What are 2 things that stimulate the release of Aldosterone?
Reduced volume of circulating fluid (Hypovolemia-->Renin-->Angiotensin-->Aldosterone)
Increased plasma K+
What are some factors associated with Aldosterone release? (in other words, what are some conditions that lead to hypovolemia or increased plasma k+?)
Trauma, Hemorrhage, Heart failure, Hyperkalemia, Angiotensin II & III, Low GFR, Liver Cirrhosis
Explain the cascade that starts with a low GFR, and renin release and ends in increased blood volume.
Decreased GFR & Na+-->Renin release-->Angiotensin I & II-->Aldosterone-->Increased Na+ resorbtion-->Water follows-->Increased blood volume
What are the 3 cellular mechanisms that are triggered to increase Na+ re absorption after Aldosterone stimulation?
1) Increased pump action
2) Increased synthesis of Na+ channels/pumps
3) Pumps up the mitochondria to make ATP to support the channels
Explain why bilateral adrenalectomy is fatal (ie. Why is loss of Aldosterone fatal?)
Low Aldosterone-->Loss of Na+, Build up of K+ & H+-->Water doesn't follow Na+ out and is lost in the urine-->Hypovolemic shock-->Death
Angiotensions stimulate the release of Aldosterone. What else do they do?
Vasoconstriction (makes sense to do this to compensate for hypovolemia)
Promote ADH secretion
What are the 2 most common causes of Adrenocortical insufficiency (Addison's)?
Iatrogenic (Corticosteroid response)
What are the main symptoms of Addison's like-disease?
Decreased Na+/K+ ratio
What is the function of Natriuretic peptide?
To reduce blood volume!!!
Antagonizes aldosterone, ADH and Angiotensin II
Reduces Na+ & Fluid levels
What are the 3 natriuretic peptides?
BNP-->Brain (Stimulated by ANP-->Vasodilation)
CNP-->CNS (Stimulated by ANP-->Vasodilation)
Which hormone causes ADH release, thirst, Vasocontriction and Aldosterone release?
Angiotensin II & III
What are the main causes of Secondary Hyporadrenocorticism (Addison's)?
Hypothalmic or Pituitary failure to release CRH & ACTH
Prolonged glucocorticoid administration
What are the main causes of primary Hyporadrenocorticism (Addison's)?
Immune mediated destruction of Adrenal cortex
Neoplasia, infection, trauma etc.. (Anything that could damage the adrenal cortex)
Adrenal suppressive drugs
What stimulates the release of E & NE from the Adrenal medulla?
Sympatheic nervous system activation
ie..emotional, biochemical or physical stress
When E & NE are released from the adrenal gland they produce a ______ response
fight or flight response
The adrenal medulla acts as both a ganglion and as an endocrine gland. Explain this.
NE release acts on target cells as the point of release
E travels, and acts on distant target cells
What are some of the physiological changes associated with the "fight or flight" response?
High Renin release
Vasodilation to skeletal muscles
Relax bronchiolar smooth muscle
Low insulin + High Glucagon
Are catecholamines lipid soluble or water soluble? Where are their receptors?
They are water soluble (NOT lipid) so their receptors are on the cell membranes