3.1

What receptor do principal cells in the cortical collecting duct express

Mineralocorticoid receptor

Which hormone normally activates MR in principal cells

Aldosterone

What is the primary effect of aldosterone on sodium in principal cells

Increased Na+ reabsorption

What potassium channel is upregulated by aldosterone in principal cells

ROMK

What ATPase is upregulated by MR activation in principal cells

Na+ K+ ATPase

Which glucocorticoid can also bind MR

Cortisol

Why does cortisol normally not activate MR in principal cells

Conversion to cortisone by 11β HSD2

What enzyme converts cortisol to cortisone in the kidney

11β HSD2

Is 11β HSD2 inducible or constitutive in principal cells

Constitutive

Can cortisone bind the mineralocorticoid receptor

No

What happens to cortisone after formation in principal cells

Exported and cleared

In normal physiology MR activation in principal cells reflects which hormone

Aldosterone

What happens when 11β HSD2 is inhibited or overwhelmed

Cortisol activates MR excessively

What sodium channel is increased when cortisol activates MR

ENaC

What electrolyte abnormality results from increased ENaC activity

Hypernatremia

What blood pressure effect results from excess MR activation

Hypertension

What potassium abnormality results from increased ROMK activity

Hypokalemia

What acid base disorder results from MR activation in intercalated cells

Metabolic alkalosis

Which disease can overwhelm 11β HSD2 due to high cortisol

Cushing syndrome

What substance in black licorice inhibits 11β HSD2

Glycyrrhetinic acid

What condition mimics hyperaldosteronism when 11β HSD2 is inhibited

Pseudo hyperaldosteronism

Which collecting duct cell type secretes hydrogen ions

Alpha intercalated cells

Which receptor do alpha intercalated cells express

Mineralocorticoid receptor

Do alpha intercalated cells express 11β HSD2

Yes

Which apical pump secretes hydrogen ions in alpha intercalated cells

H+ ATPase

Which apical exchanger secretes both hydrogen and potassium

H+ K+ ATPase

Which basolateral exchanger moves bicarbonate into blood

AE1

What ion is exchanged for bicarbonate by AE1

Chloride

How does excess aldosterone affect hydrogen secretion

Increases secretion

What enzyme generates new hydrogen and bicarbonate inside the cell

Carbonic anhydrase

What happens to intracellular bicarbonate during excess hydrogen secretion

Accumulates

How does bicarbonate exit alpha intercalated cells

Via AE1

What plasma change results from bicarbonate accumulation

Increased plasma bicarbonate

What acid base disorder results from this process

Metabolic alkalosis

Which enzyme converts cortisone to cortisol in the liver

11β HSD1

Where is 11β HSD1 primarily expressed

Hepatocytes

During what metabolic state is 11β HSD1 activity increased

Prolonged fasting

What metabolic pathway is enhanced by hepatic cortisol

Gluconeogenesis

Which hormones act with cortisol to maintain glucose during fasting

Glucagon and epinephrine

What is the renal role of 11β HSD2

Protect kidney from cortisol MR effects

What is the hepatic role of 11β HSD1

Amplify cortisol metabolic effects

What are the adrenal cortex layers from outer to inner

Glomerulosa fasciculata reticularis

Which adrenal layer produces aldosterone

Zona glomerulosa

Which adrenal layer produces cortisol

Zona fasciculata

Which adrenal layer produces DHEA

Zona reticularis

Which adrenal structure produces catecholamines

Medulla

What is the primary stimulus for aldosterone release

Angiotensin II

What electrolyte directly stimulates aldosterone secretion

Potassium

What pituitary hormone weakly stimulates aldosterone

ACTH

What hormone stimulates zona fasciculata

ACTH

What hormone stimulates zona reticularis

ACTH

Where is CRH produced

Paraventricular nucleus

Which neurons secrete CRH

Parvocellular neurons

How does CRH reach the anterior pituitary

Hypophyseal portal system

Which pituitary cells respond to CRH

Corticotrophs

What prohormone is secreted by corticotrophs

POMC

Which enzyme cleaves POMC into ACTH

PC1

Which adrenal zones respond to ACTH

Fasciculata and reticularis

What brain structure links stress to CRH release

Amygdala

Does stress directly release cortisol

No

What is the hormonal sequence from stress to cortisol

CRH then ACTH then cortisol

What two sites receive negative feedback from cortisol

Hypothalamus and pituitary

Do cortisol receptors mediating feedback have high or medium affinity

Medium

When is cortisol feedback strongest

When cortisol is elevated

Where is DHEA produced

Zona reticularis

What percentage of DHEA leaves the adrenal unchanged

About ninety percent

What fraction of DHEA is converted to testosterone in the adrenal

About ten percent

Which enzyme converts DHEA to androstenedione

3β HSD

Which enzyme converts androstenedione to testosterone

17β HSD

Which enzyme converts androgens to estrogens

Aromatase

Is aromatase present in the adrenal cortex

No

What tissues contain aromatase

Ovaries adipose skin

What is the main estrogen source before menopause

Ovaries

What percent of estrogen comes from adipose before menopause

About ten percent

What is the main estrogen source after menopause

Adipose tissue

What percent of estrogen comes from adipose after menopause

Up to seventy percent

What condition causes excess DHEA from high ACTH

ACTH dependent Cushing syndrome

What androgen related symptom may occur in females

Hirsutism

What reproductive effect can excess androgens cause

Amenorrhea

What does Cushing syndrome describe

Hypercortisolism from any cause

What does Cushing disease describe

Pituitary ACTH secreting adenoma

Which is more common endogenous cause

Cushing disease

What defines ACTH dependent Cushing syndrome

Excess ACTH driving cortisol

What defines ACTH independent Cushing syndrome

Autonomous adrenal cortisol secretion

What happens to ACTH in ACTH independent disease

Suppressed

What tumor causes Cushing disease

Corticotroph adenoma

Why does cortisol fail to suppress ACTH in Cushing disease

Tumor lacks cortisol receptors

What happens to CRH levels in Cushing disease

Suppressed

What happens to adrenal glands in chronic ACTH excess

Bilateral hyperplasia

What is a common source of ectopic ACTH

Small cell lung carcinoma

Can cortisol suppress ectopic ACTH secretion

No

What happens to adrenal size in ectopic ACTH syndrome

Hyperplasia

What causes metabolic alkalosis in hypercortisolism

Excess MR activation

What electrolyte abnormalities accompany alkalosis in Cushing syndrome

Hypokalemia

What blood pressure change occurs in chronic cortisol excess

Hypertension

What glucose abnormality occurs in Cushing syndrome

Hyperglycemia

What happens to muscle protein in chronic cortisol excess

Catabolism

What immune effect does cortisol have

Immunosuppression

What is the untreated five year survival of Cushing syndrome

About fifty percent