Hypothalamic and Pituitary relations part 2 Flashcards
Where are the Adrenal Glands located?
Above the kidneys
What does the Hypothalamus release to the Anterior Pituitary in the HPA axis?
CRH
What does the Anterior Pituitary release to the Adrenal cortex in the HPA axis?
ACTH
What does the Adrenal cortex release in response to ACTH?
Cortisol
HPA axis
Hypothalamic-Pituitary-Adrenal Axis
What are the main functions of Cortisol?
Immune suppression
Gluconeogenesis
Protein Catabolism
Lipolysis
What activates the Hypothalamus to release CRH?
Stress and the Circadian Rhythm
Cortisol is released due to what acting on the Hypothalamus?
Stress and the Circadian Rhythm
Where does Cortisol have negative feedback?
At the Anterior pituitary (ACTH) and at the Hypothalamus (CRH)
Do Androgens have negative feedback?
NO
What are the 3 zones of the Adrenal Cortex?
Zona Granulosa
Zona Fasciculata
Zona Reticularis
Zona Granulosa releases?
Mineralcorticoids - Aldosterone
Zona Fasciculata releases?
Glucocorticoids - Cortisol
Zona Reticularis releases?
Androgens - secondary sex characteristics
When are ACTH and Cortisol secretion rates the highest?
In the morning
When are ACTH and cortisol secretion rates the lowest?
In the evening
What activates the release of Aldosterone?
Low sodium/High potassium OR
LOW BP
Describe the pathway for how to release Aldosterone from the Adrenal Cortex
- Low sodium/High potassium or LOW BP act on the Kidney to release Renin
- Renin activates Angiotensin to Angiotensin 1 which then goes to Angiotensin 2
- Angiotensin 2 acts on the Zona Glomerulosa to release Aldosterone
- Increased sodium/water absorption and increased BP
What does the kidney release to help activate Aldosterone secretion?
Renin
Where is the Angiotensin cascade found?
Liver
Where does low sodium/high potassium or Low BP act to activate Aldosterone release?
Kidney
Hypersecretion of glucocorticoids (cortisol)
Cushing’s Disease
Symptoms of Cushing’s Disease
Truncal obesity, buffalo hump, moon face, purple striae, high BP, easy bruising
What test can distinguish what is causing the increased cortisol levels for Cushing’s Disease?
High-Dose Dexamethasone Suppression Test
What is the expected response of the HIGH-Dose Dexamethasone Suppression Test?
Decreased levels of ACTH that lead to decreased Cortisol levels
Describe the results of Cushing’s Disease caused by an Adrenal Tumor
Low CRH
Low ACTH
HIGH Cortisol
Describe the results of Cushing’s Disease caused by an Anterior Pituitary Tumor
Low CRH
HIGH ACTH
HIGH Cortisol
Describe the results of Cushing’s Disease caused by an Ectopic secreting ACTH tumor
Low CRH
Low ACTH at pituitary
HIGH ACTH from another source
HIGH cortisol
Describe the results of Cushing’s Disease caused by exogenous glucocorticoid drugs
Low CRH
Low ACTH
LOW cortisol
Why are all outputs low if Cushing’s Disease is caused by exogenous glucocorticoid drugs?
Exogenous glucocorticoids have the same negative feedback loop as real cortisol, thus all levels of the hormones will be low from their regular source
What may atrophy due to exogenous glucocorticoid drug intake?
Adrenal cortex cells that normally produce cortisol (fasciulata)
What are a few exogenous glucocorticoid drugs?
Prednisone
Methylprednison
Dexamethasone
What is the action of Aldosterone?
Increase sodium and water absorption and Increase BP
Increased levels of ACTH can lead to?
Hyperpigmentation (skin darkening)
Hyposecretion of mineralcorticoids and glucocorticoids
Addison’s Disease
Addison’s disease may also be known as
Adrenal Gland insufficiency
What test can be used to detect Adrenal Gland insufficiency?
Cosyntropin (synthetic ACTH) stimulation test
Low morning cortisol levels (normal is high) can confirm what?
Adrenal gland insufficiency
If morning cortisol levels are low and ACTH is high, what is the diagnosis?
Primary Adrenal Gland insufficiency
What are the levels of Cortisol and Aldosterone for Primary Adrenal Gland Insufficiency?
BOTH LOW
If morning cortisol levels are low and ACTH is low/normal, what is the diagnosis?
Secondary/Tertiary Adrenal Gland insufficiency
What are the levels of Cortisol and Aldosterone for Secondary/Tertiary Adrenal Gland insufficiency?
LOW cortisol
ALDOSTERONE IS NORMAL due to Renin system being unaffected in the liver
Main physical sign of Primary adrenal gland insufficiency?
Hyperpigmentation - due to high ACTH and low cortisol
Excessive release of Aldosterone, may be due to Adenoma in Adrenal cortex
Primary Hyperaldosteronism
Excessive release of Renin that causes excess Aldosterone
Secondary Hyperaldosteronism
What characterizes congenital enzyme deficiencies relating to the adrenal glands?
Enlargement of the adrenal glands due to HIGH levels of ACTH because the cortisol is LOW and thus there is an absence of (-) feedback on ACTH
Adrenal Hyperplasia
Enlargement of adrenal glands
17 alpha enzyme deficiency
HIGH aldosterone = HIGH BP LOW androgens (sex hormones) = underdeveloped
21 beta enzyme deficiency
LOW aldosterone = LOW BP HIGH androgens (sex hormones) = early puberty, virilization
11 beta enzyme deficiency
LOW aldosterone , but somehow HIGH BP HIGH androgens (sex hormones) = virilization LOW renin activity
What are the levels of cortisol in all congenital enzyme deficiencies for the adrenal cortex?
LOW
What is virilization?
Male hair growth characteristics on females
What is a pheochromocytoma?
Benign, unilateral tumor that secretes catecholamines
Catecholamines
Norepinephrine and Epinephrine
What stimulates release of NE and E?
Acetylcholine
How do you diagnose a pheochromocytoma?
Increased NE/Epi and increased metabolic byproducts
What are the symptoms you would see with increased catecholamines?
Sweating, Hypertension, palpitations, headaches
Which catecholamine is synthesized in a vesicle?
Norepinephrine