Step by Step
1
The adrenal cortex — three zones, "Salt, Sugar, Sex"
From outside in: the zona glomerulosa produces aldosterone (a mineralocorticoid, promoting sodium retention and potassium excretion — "Salt"); the zona fasciculata produces cortisol (a glucocorticoid, the stress hormone — "Sugar"); the zona reticularis produces androgens like DHEA, weak sex hormones especially important in females ("Sex").
2
What controls each zone
ACTH controls the zona fasciculata and reticularis, but NOT the zona glomerulosa — aldosterone production is instead controlled by the RAAS system and potassium levels directly.
3
The adrenal medulla — a modified sympathetic ganglion
Chromaffin cells in the adrenal medulla secrete epinephrine (about 80%) and norepinephrine (about 20%) in response to sympathetic stimulation — this is part of the fight-or-flight response.
4
Pheochromocytoma
A catecholamine-secreting tumor of the adrenal medulla, causing episodic hypertension, headache, and sweating due to excessive, unpredictable epinephrine/norepinephrine release.
Applied Walkthrough
1
During a stressful event, ACTH from the pituitary stimulates the zona fasciculata to release cortisol — raising blood glucose and suppressing inflammation as part of the body's stress response.
2
Separately, if blood pressure or sodium levels drop, the RAAS system (not ACTH) stimulates the zona glomerulosa to release aldosterone — retaining sodium and water to help restore blood pressure.
3
Meanwhile, in a genuine fight-or-flight situation, sympathetic nervous system activation directly stimulates the adrenal medulla's chromaffin cells to release epinephrine and norepinephrine, producing the immediate physiological changes associated with acute stress (increased heart rate, blood flow to muscles).
4
In a patient with a pheochromocytoma, this same catecholamine-releasing machinery in the adrenal medulla becomes unpredictable, causing episodic spikes in blood pressure, headache, and sweating — driven by tumor cells rather than an appropriate physiological trigger.
Exam Application
Exams test whether you can match each adrenal cortex zone (glomerulosa, fasciculata, reticularis) to its hormone (aldosterone, cortisol, androgens) using the "Salt, Sugar, Sex" mnemonic, and whether you know that aldosterone (unlike cortisol and androgens) is controlled by RAAS rather than ACTH.
⚠ Common Trap
The most common trap is assuming ACTH controls all three adrenal cortex zones — it controls the zona fasciculata and zona reticularis, but aldosterone production in the zona glomerulosa is controlled separately, by the RAAS system and potassium levels.
✓ Quick Self-Check
1. What are the three zones of the adrenal cortex, from outside in, and what does each produce?
Zona glomerulosa (aldosterone), zona fasciculata (cortisol), zona reticularis (androgens) — "Salt, Sugar, Sex."
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2. What controls aldosterone production, if not ACTH?
The RAAS system and potassium levels.
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3. What does the adrenal medulla secrete, and in what approximate proportions?
Epinephrine (about 80%) and norepinephrine (about 20%).
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4. What triggers adrenal medulla hormone release?
Sympathetic nervous system stimulation.
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5. What is a pheochromocytoma, and what symptoms does it cause?
A catecholamine-secreting tumor of the adrenal medulla, causing episodic hypertension, headache, and sweating.
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