Week 2 - Adrenal Glands

Neil lecture...

Where is the adrenal gland located?

Lies cranial to kidneys - adhered to aorta on left and caudal vena cava on right

What is the blood supply for the adrenal gland?

Supplied by the superior, middle, and inferior suprarenal arteries

• cortex: cortical arteries → cortical capillaries → medullary veins → central vein

• medulla: medullary artery → medullary capillaries → medullary veins → central vein

The central vein connects to either the vena cava or renal vein depending on which side the gland is on

What hormones get produced from pregnenolone? Where do these hormones get produced?

• In zona glomerulosa: mineralocorticoids

• In zona fasciculata: glucocorticoids

• In zona reticularis: androgens

Why is mineralocorticoids important? What does it do?

stimulates the reabsorption of Na from urine, saliva, gastric juices, and sweat (essential for life)

Why is glucocorticoids important? What does it do?

• metabolic homeostasis

• adaptation to stress

• anti-inflammatory

Why is andorgens important? What does it do?

• precursors of sex steroids

• sexual differentiation

• protein anabolism

What ae the types of Conn’s syndrome? (hyperaldosteronism) Who does it affect?

• Primary: adrenal tumor, hypersecreting aldosterone and low renin

• Secondary: bilateral adrenal hyperplasia

Affects older cats, occasionally dogs

What are some symptoms of Conn’s syndrome?

• hypokalemia (incr K excretion)

• hypernatremia (incr plasma Na)

• metabolic alkalosis

• lethargy

• hypertension

• blindness

• renal failure

• muscle weakness

What are the types of Cushing’s syndrome? (hyperadrenocorticism) Who does it affect?

1. Adrenal tumors: secrete cortisol independently of ACTH (15% cushings dogs)

2. Pituitary hyperplasia: non-pituitary ACTH- or CRH-secreting tumors

3. Pituitary tumor: excess production of ACTH (85% of cushings dogs)

Affects dogs, cats, horses

What are some symptoms of Cushing’s syndrome?

• Polyuria, polydipsia, polyphagia

• lethargy

• recurrent UTIs

• hair loss (symmetrical, dogs)

• long hair, delayed shedding (horses)

• skin diseases (dogs), thin skin (cats)

• hepatomegaly, resulting in pot belly

• osteoporosis

• altered carbohydrate metabolism (can predispose horses to laminitis)

What are the types of Addison’s disease (adrenocortical insufficiency) Who does it affect?

• Primary: defect at the adrenal gland, most common, autoimmune condition

• Secondary: pituitary tumor, or following discontinuation of long-term steroid treatment

Affects cats and dogs

What are some symptoms of Addison’s disease?

• lethargy and weakness

• poor appetite

• vomiting, diarrhea, weight loss

• depression

• dehydration

• polydipsia, polyuria

• low plasma glucose

• metabolic acidosis

• low body temp

• shaking

• weak pulse, slow heart rate (K retention)

• increased pigmentation

• addisonian crisis, shock and collapse (dogs)

• inability to cope with stress

What does the zona glomerulosa do?

• produces mineralocorticoids, primary aldosterone

• regulated by renin-angiotensin system

What does the zona fasciculata do?

• largest zone in the cortex

• produces glucocorticoids cortisol/corticosterone

• regulated by hypothalamus via pituitary

What does the zona reticularis do?

• innermost zone of the cortex

• produces androgens and glucocorticoids

• regulated by hypothalamus via pituitary

• size varies under different physiological conditions

What hormone is produced in the medulla?

Catecholamines

What does the hormone catecholamines produce?

Produces dopamine which is converted into noradrenaline/norepinephrine which is converted into adrenaline/epinephrine

• secretion is 80% adrenaline and 20% noradrenaline

What is the regulation of catecholamine secretion?

• synthesized and stored in chromaffin cells

• Basal release from adrenal medulla into peripheral circulation

• release from chromaffin cells is stimulated by ACh released from preganglionic SNS fibers