11 - CIS Hypothalamic and Pituitary Relationships and Biofeedback Pt. II Flashcards
This is located immediately above the kidneys.
Adrenal glands (also called suprarenal)
What are the layers of the adrenal gland?
Capsule
Cortex
Medulla
What are the components of the adrenal cortex?
Zona Glomerulosa
Zona Fasciculata
Zona Reticularis
What do each layer of the adrenal cortex and adrenal medulla secrete?
Zona Glomerulosa – Mineralocorticoid (Aldosterone)
Zona Fasciculata – Glucocorticoids (Cortiso); Androgens (DHEAS)
Zona Reticularis – Androgens (DHEAS); Glucocorticoids (Cortisol)
Medulla – Chromaffin cells secrete Catecholamines (NE and E)
These are catecholamines that are rapid responders to stress (i.e., hypoglycemia, exercise).
Epinephrine
Norepinephrine
This is a steroid (glucocorticoid) that is a longer-acting stress-response steroid hormone. It regulates glucose utilization, immune and inflammatory homeostasis.
Cortisol
This is a steroid (mineralocorticoid) that regulates salt and volume homeostasis.
Aldosterone
This is a steroid that is an androgen precursor.
DHEAS
Briefly describe the HPA axis and its negative feedback control.
Hypothalamus releases CRH, stimulates Anterior Pituitary to release ACTH, stimulates Adrenal Cortex to release Cortisol.
Cortisol gives negative feedback to Hypothalamus and Anterior Pituitary to inhibit release of CRH and ACTH.
***Cortisol will also inhibit the process of infection and inflammation (via cytokines)
What are the main things that will stimulate CRH to start producing?
Physical stress (i.e., surgery) Emotional stress (i.e., fear) Metabolic stress (i.e., acute hypoglycemia) Infection and inflammation (via cytokines)
Where does cortisol go and what does it do?
Immune system – Suppresses it
Liver – Gluconeogenesis
Muscle – Protein catabolism
Adipose tissue – Lipolysis
What is the circadian rhythm like for cortisol?
Secretory rates are high in the early morning but low in the late evening.
ACTH also induces the secretion of _______ from the Zona Reticularis. Unlike Cortisol, this has no feedback mechanism on CRH or ACTH.
Androgens (DHEAS)
Briefly explain the process of increasing blood pressure by using Aldosterone.
Low BP signals to kidney to increase its release of Renin –
The Liver also releases Angiotensinogen –
Renin cleaves Angiotensinogen into Angiotensin I –
ACE (from lungs) will make Angiotensin I into Angiotensin II –
Angiotensin II goes to the Adrenal Cortex and induces it to secrete Aldosterone –
Aldosterone increases water and sodium reabsorption –
Increases BP
The following symptoms are most representative of what disease?
- Truncal obesity (abdomen)
- Moon face
- “Buffalo hump”
- Easy bruising
- Dark red or purple stretch marks
- Acne
Cushing’s Syndrome
In this test, it differentiates patients that have CS (Cushing’s Syndrome) from those that do not have it. If there is no ACTH suppression, then they have CS.
Low-Dose Dexamethasone Suppression Test
- **This inhibits ACTH (CS is caused by too much Cortisol).
- **This test does NOT specify the source of the ACTH over-production (that is high-dose).
In this test, it distinguishes patients with CS caused by pituitary ACTH-secreting tumor from CS caused by a non-pituitary ACTH-secreting tumor. It is used after the initial diagnosis of CS is made.
High-Dose Dexamethasone Suppression Test
Explain how the High-Dose Dexamethasone Suppression test works.
A high-dose of Dexamethasone is given to the patient. If there is a pituitary tumor, there will be decreased ACTH because of the negative feedback effect on the pituitary. If there is an ectopic tumor, there is no change in ACTH because there is no negative feedback effect on this type of tumor.
What are the ways of getting CS?
Exogenous glucocorticoid excess (latrogenic – via drugs)
Pseudo-Cushing’s Syndrome – via major depression, anxiety, acute/chronic illness, alcoholism
ACTH-dependent – Pituitary adenoma (Cushing’s Disease), Ectopic ACTH-secreting tumor, CRH-secreting tumor
ACTH-independent – Adrenal Adenoma, Adrenal Carcinoma
Exogenous glucocorticoids have the same negative feedback effect as Cortisol, and due to their use they could cause the atrophy of the adrenal cells in the _______ _______ that produce Cortisol.
Zona Fasciculata
What are examples of synthetic glucocorticoids?
Prednisone
Methylprednisone
Dexamethasone
The primary action of Aldosterone is renal ________ reabsorption.
Sodium
Aldosterone combines with a cytoplasmic receptor (in kidney cells). This hormone-receptor complex initiates transcriptions in the nucleus. Translation and protein synthesis makes new protein channels and pumps. Aldosterone-induced proteins modulate existing channels and pumps. These result in increased ________ reabsorption and ________ secretion.
Sodium
Potassium
This is produced in the Anterior Pituitary and is derived from post-translational processing of POMC (pro-opiomelanocortin). It is a peptide hormone.
ACTH
In non-pituitary cells, what does ACTH induce?
Melanin synthesis (can cause hyperpigmentation)
What disease presents with increased ACTH and hyperpigmentation as a result?
Addison’s Disease