The Endocrine System: Adrenal Gland Flashcards
Adrenal Gland Anatomy
Rest on the superior aspect of each kidney
Surrounded by adipose
Has neural and glandular components
Adrenal Gland
What is the structure of the adrenal gland?
Two concentric layers
* Medulla (neural crest) - post ganglion neurons, chromaffin cells
* Cortex (mesodermal) - steroid-hormone producing cells, 3 layers - contains a lot of sinisoids
Where are Adrenal Hormones released?
Released into nearby blood vessels
Steroid hormones in the cortex
Peptide hormones (catecholamines) in the medulla (release induced by nerve signal)
Adrenal Medulla: Neural
The adrenal medulla is derived from _ and innervated by _.
neural tissue
sympathetic ganglion cells
Adrenal Medulla: Neural
The adrenal medulla contains _ and produces _.
Chromaffin cells (secretory cells)
Epinephrine (adrenaline) and norepinephrine
Adrenal Medulla: Neural
How is the adrenomedullary vein unique from other veins in the body?
It has longitudinal smooth muscle instead of circular smooth muscle
Adrenal Medulla: Neural
Why does the adrenomedulalry vein have different smooth muscle from other veins?
It allows the vein to squeeze and force blood out quickly
This is why you can get sudden spikes of adrenaline
Adrenal Medulla: Neural
Chromaffin cells
Two populations:
* one makes norepinephrine
* the other makes epinephrine
Store hormone in granules
Adrenal Medulla: Neural
Catecholamine Synthesis
Tyrosine (aa) → Dopamine (neurotransmitter) → norepinephrine → epinephrine
Adrenal Medulla: Neural
What are some of the metabolic effects of epinephrine release?
- Vasoconstriction of smooth muscle
- Increased BP ( due to vasoconstriction or renin release)
- Altered HR
- Elevated blood glucose (↑glucagon)
- ↑insulin
Adrenal Medulla: Neural
Pheochromocytoma
Rare tumor of the chromaffin cells that increases adrenaline production
Adrenal Medulla: Neural
The adrenomedulalry vein drains directly into the _ on the right side or the _ on the left side
Inferior vena cava
left renal vein
Adrenal Medulla: Neural
What supplies the adrenomedullary vein?
sinusoids from the cortex and medulla
Adrenal Medulla: Neural
All hormones exit the adrenal gland through _.
Adrenomedullary vein
Adrenal Cortex: Glandular
What is the organization of the adrenal cortex?
3 Zones:
* Zona glomerulosa - cells are organized in ball like structures
* Zona fasciculata - cells are organized in plates
* Zona reticularis - not well organized, meshwork
Adrenal Cortex
Spongiocytes
Have alot of lipid
Store a lot of cholesterol to make cortisol
Adrenal Cortex
Zona glomerulosa
Produce mineralocorticoids - primarily aldosterone
Under Ang II control
Cells are organized in ball like structures
Adrenal Cortex
Zona fasiculata
Produce glucocorticoids - primarily cortisol (stress hormone)
Under ACTH control
Cells are organized in plates
Adrenal Cortex
Zona reticularis
Produces cortisol and weak androgen DHEA (converted to testosterone)
Under ACTH control
Not well organized, meshwork
Adrenal Cortex
Steroid Hormone Synthesis
Cholesterol → progesterone → cortisol (ZF/ZR)
Cholesterol → progesterone → aldosterone (ZG)
Cholesterol → progesterone → weak androgens (ZR)
Adrenal Cortex
Why are different hormones produced from cholesterol?
Cells contain different enzymes/proteins result in the production of different hormones
I.E. ZG can’t synthesize cortisol because it doesn’t have the CYP17 enzyme but ZF can because it does have the CYP17
Adrenal Cortex
What is the function of aldosterone?
Steroid Hormone
Regulation of extracellular fluid volume
* increased sodium transport reduces water excretion
Control of potassium homeostasis
* reduced sodium excretion increases potassium excretion
Adrenal Cortex
How does aldosterone function?
Binds to mineralocorticoid receptor in cytoplasm
Acts through aldosterone-regulated kinase to effect activity of sodium channels
Adrenal Cortex
What is the function of Cortisol?
The stress hormone
Promotes gluconeogenesis
Promotes glycogen formation in the liver
Induces fat mobilization in adipose tissue
Induces protein degredation in muscle
Suppresses the immune system
* cytokine production decreases
* lymphopoiesis is reduced
Adrenal Cortex
How do hormones exit the adrenal cortex?
Blood vessels that bring nurtients in, bring hormones out
