Adrenal Glands Flashcards
What are the layers of the adrenal glands?
- Outer Cortex / Zona Glomerulosa
- produces mineralcorticoids (mostly aldosterone) - Middle Cortex / Zona Fasiculata
- produces glucocorticoids (cortisol, cortisone, hydrocortisone) - Inner Cortex / Zona Reticularis
- produces androgens (DHEA and androstenedione) - Medulla
- produces catecholamines (epinephrine, norepinephrine) from chromaffin cells
What is the arterial and venous supply of the adrenal glands?
Arterial:
- suprarenal / adrenal arteries (L2 from abdominal aorta)
- superior, middle and inferior branches
Venous:
- right adrenal vein: directly into IVC
- left adrenal vein: into orenal vein, then IVC
What are the 3 zones of the adrenal cortex?
- zona glomerulosa / outer (mineralcorticoids)
- zona fasiculata / middle cortex (glucocorticoids)
- zona reticularis / inner cortex (androgens)
What are the 4 types of hormones produced by the adrenal gland?
- mineralcorticoids (aldosterone)
- produced by outer cortex / zona glomerulosa - glucocorticoids (cortisol, cortisone, hydrocortisone)
- produced by middle cortex / zona fasiculata - androgens (DHEA, androstenedione)
- produced by inner cortex / zona reticularis - catecholamines (epinephrine, norepinephrine)
- produced by chromaffin cells in medulla
What are chromaffin cells?
- located in adrenal medulla
- modified postganglionic sympathetic neurons (from pre-ganglionic SNS fibres T10-11 that synapse at adrenal medulla)
- synthesize catecholamines (epinephrine 80%, norepinephrine 20%)
What is the innervation of the adrenal glands?
SNS: abdominopelvic splanchnic T10-L2
PNS: unclear, probably CNX
visceral afferents
Whicih hormone regulates the activity of the adrenal glands via a negative feedback loop?
Cortisol
- a negative feedback loop to anterior pituitary and hypothalamus
What is the anatomical structure of the adrenal glands?
Shapes:
- right: pyramidal
- left: semi lunar
Layers:
- cushioned in a fibrous capsule and cushion of fat
- cortex (outer glomerulosa, middle fasiculata, inner reticularis)
- medulla
What are the 2 categories of hormones produced by the adrenal gland?
Steroid
- produced by cortex
- outer / gomerulosa: mineralcorticoids
- middle / fasiculata: glucocorticoids
- inner / reticularis: androgens
Catecholamines
- produced by chromaffimin cells in medulla
- epinephrine / norepinephrine
What are catecholamiens and their actions?
- produced by adrenal medulla
- epinephrine and norepinephrine
Actions:
- augment activity of SNS
- vasoconstriction (increases BP)
- increases HR and cardiac contractility
- increases blood glucose
What is the lymphatic drainage of the adrenal glands?
rich lymphatic drainage via adrenal lymphatic vessels into lumbar nodes
What is the adrenal gland response to short term stress?
- SNS activation
- release of catecholamines from adrenal medulla (epinephrine and norepinephrine)
Actions:
- increases HR and cardiac contractility
- vasoconstricton and increased HR
- augments SNS activity
- dilation of bronchioles
- increases blood glucose (liver converts glycogen stores to glucose and releases into blood stream)
What is the adrenal gland response to long term stress?
- hypothalamus releases corticotrophic releasing hormone (CRH)
- triggers anterior pituitary to release ACTH (adreno-corticotrophic hormone)
- triggers secretion of steroid hormones from adrenal cortex
Actions:
- release of aldosterone (mineralcorticoid) causes sodium chloride reabsorptiono in kidneys and increased blood volume / blood pressure
- release of glucocorticoids (cortisol, cortisone, hydroocortisone) causes gluconeogenesis, increased blood glucose, and anti-inflammatory / immune system inhibition
