Adrenal Glands form/functions

The adrenal gland is composed of two embryologically distinct tissue —the outer adrenal cortex and inner adrenal medulla.

On each kidney

• Functions to produce steroid hormones • Is the outer portion • Has 3 layers

• Functions to produce amine hormones • Inner portion

• Zona glomerulosa • Zona fasciculata • Zona reticularis

• Secretes mineralocorticoids, such as aldosterone • Critical for salt balance, potassium excretion, acid–base homeostasis, and regulation of blood pressure

• Secretes glucocorticoids such as cortisol • critical for carb metabolism and blood pressure

• Secretes sex hormones such as the androgens • Required for sexual function and contribute less than the gonads

• Produced in G-zone • Controls amount of fluid in body (Na, Cl, and water retention, K and H excretion) • renin-angiotensin system controls its production

Increases Na excretion Decreases K excretion

Increases salt and water reabsorption and increases blood pressure/volume (vasoconstriction)

Increased BP and blood volume suppresses renin secretion, thus suppressing aldosterone synthesis

It’s an adrenal disease, such as an aldosterone-secreting adrenal adenoma or carcinoma, or adrenal cortex hyperplasia

Aldosterone-secreting adenoma

Renin-angiotensin disorder where there’s excess renin synthesis due to renin-secreting renal tumor, thus causing malignant hypertension

• Increased sodium levels • Symptoms: hypokalemia, mild metabolic alkalosis, increase blood volume and BP

Atrophy of adrenal glands

• Addison’s disease: reduced aldosterone and glucorticoid production • Congenital deficiency of 21-hydroxylase enzyme

• Reduced aldosterone and cortisol secretion • Reduced blood glucose • Reduced Na and Cl • Increased ACTH • Increased beta-MSH • Increased K • Skin pigmentation • Muscle weakness • Weight loss • Decreased BP • Nausea • Diarrhea

• Bronze skin • Changes in body hair distribution • GI disturbances • Weakness • Weight loss • Hypoglycemia • Postural hypotension

• Anti-insulin effects of carbs -> increased blood glucose • More gluconeogenesis, lipolysis, protein catabolism • Less protein synthesis, antibody formation, inflammatory response

Cortisol and ACTH

Positive feedback loop Hypothalamus secretes CRH -> anterior pituitary secretes ACTH -> adrenal gland secretes cortisol, which goes back to stimulate the hypothalamus

Low cortisol = more ACTH released High cortisol = less ACTH released