Adrenal Cortex & Medulla-Dr. Bracha

Created by cdykhuis 

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38 terms

What is Cushing's?

Hyperadrenocorticism

What is addison's like disease?

Hypoadrenocorticism

What does it mean if your dog has a primary hyperadrenocorticism?

There is an adrenocortical tumor

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)?

PU/PD
Abdominal enlargement
Exercise intolerance
Lethary & Obesity

What are the main symptoms of Equine Cushing's disease?

Hirsutism
Laminitis
PU/PD

From where is Aldosterone secreted?

The Zona glomerulosa of the adrenal cortex (SALT, Sugar, Sex)

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

What do Antiontensin II & III stimulate?

Aldosterone release (They are released from low GFR)

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 2 things that stimulate renin release?

Decreased NaCl in the tubules
Renal hypotension

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)
Stimulate Thirst
Promote ADH secretion

What are the 2 most common causes of Adrenocortical insufficiency (Addison's)?

Autoimmune
Iatrogenic (Corticosteroid response)

What are the main symptoms of Addison's like-disease?

Hyponatermia
Hyperkalemia
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

Where is Natriuretic peptide made?

It is synthesized by atrial myocytes

What triggers release of Natriuretic peptide?

Plasma volume expansion in the atria

What is the function of ANP on peripheral blood vessels?

Vasodilation

What are the 3 natriuretic peptides?

ANP-->Atrial
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

If there is hypovolemia and hyperkalemia what hormone will be released?

Aldosterone

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

The adrenal medulla is a modified sympathetic ______

Ganglion

What are released from the adrenal medulla?

Catecholamines (Epi & NorEpi)

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

Which receptors respond more to NE?

Alpha 1 & 2s (Betas respond more to Epinephrine)

Which receptors respond more to E?

Beta2 (Alphas respond more to NE)

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?

Increased CO
High Renin release
Vasodilation to skeletal muscles
Pupillary dilation
Relax bronchiolar smooth muscle
Low insulin + High Glucagon

What are the 4 hormones that antagonize insulin?

Cortisol, GH, Epinephrine & 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

What is a pheochromocytoma?

A catecholamine secreting tumor
90% are located in the adrenal glands
They are NOT intervated so release may be continuous or episodic

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