Zona Glomerulosa Flashcards

Review the zona glomerulosa, its histological organization, aldosterone synthesis, enzyme expression, and hormonal regulation.

Card 1 of 26Question

What is the zona glomerulosa?

The outermost layer of the adrenal cortex, specialized for mineralocorticoid synthesis.

In This Section

1. What is the zona glomerulosa?

The outermost layer of the adrenal cortex, specialized for mineralocorticoid synthesis.

2. Where is the zona glomerulosa located within the adrenal gland?

Immediately beneath the connective tissue capsule and superficial to the zona fasciculata.

3. Approximately what proportion of the adult adrenal cortex is occupied by the zona glomerulosa?

Approximately 10% to 15% of the cortical thickness.

4. How are endocrine cells arranged in the zona glomerulosa?

In rounded clusters and curved arches separated by capillaries.

5. How do zona glomerulosa cells typically appear in routine histological sections?

Small columnar or pyramidal cells with relatively compact, lightly eosinophilic cytoplasm.

6. How does the lipid content of zona glomerulosa cells compare with that of zona fasciculata cells?

Zona glomerulosa cells generally contain fewer lipid droplets.

7. Which organelles are prominent in zona glomerulosa cells because of their steroid-producing function?

Smooth endoplasmic reticulum and mitochondria with tubular cristae.

8. Which class of steroid hormones is produced by the zona glomerulosa?

Mineralocorticoids.

9. What is the principal hormone secreted by the zona glomerulosa?

Aldosterone.

10. What is the primary physiological function of aldosterone?

To promote renal sodium reabsorption and potassium excretion, helping regulate extracellular fluid volume.

11. Which substance serves as the precursor for aldosterone synthesis?

Cholesterol.

12. Which enzyme is characteristic of aldosterone-producing zona glomerulosa cells?

Aldosterone synthase (CYP11B2).

13. Which enzyme is absent from zona glomerulosa cells, preventing significant cortisol synthesis?

17-alpha-hydroxylase (CYP17A1).

14. What are the two principal physiological regulators of aldosterone secretion?

Angiotensin II and extracellular potassium concentration.

15. Which endocrine system primarily regulates zona glomerulosa activity?

The renin-angiotensin-aldosterone system (RAAS).

16. Which component of the renin-angiotensin system directly stimulates aldosterone-producing cells?

Angiotensin II acting primarily through angiotensin type 1 receptors.

17. How does an elevated plasma potassium concentration affect aldosterone secretion?

It directly stimulates zona glomerulosa cells to increase aldosterone release.

18. What is the role of adrenocorticotropic hormone (ACTH) in zona glomerulosa function?

It can transiently stimulate aldosterone secretion but is not its principal long-term regulator.

19. Which intracellular ion acts as a major signaling mediator of aldosterone synthesis?

Calcium ions, whose increased intracellular concentration stimulates steroidogenic activity.

20. How does atrial natriuretic peptide affect aldosterone secretion?

It inhibits aldosterone production by zona glomerulosa cells.

21. What type of capillaries are associated with the zona glomerulosa?

Fenestrated sinusoidal capillaries that permit efficient exchange of steroid hormones.

22. Where does blood from the zona glomerulosa flow within the adrenal cortex?

Inward through cortical sinusoids toward the zona fasciculata, zona reticularis, and medulla.

23. What is the embryological origin of zona glomerulosa cells?

Mesoderm-derived adrenal cortical cells originating from the coelomic epithelium.

24. Which disorder results from autonomous excessive aldosterone secretion by the adrenal cortex?

Primary aldosteronism.

25. What is an aldosterone-producing adenoma traditionally associated with?

Conn syndrome, a form of primary aldosteronism.

26. What electrolyte abnormality may result from excessive aldosterone secretion?

Hypokalemia due to increased renal potassium excretion.