This chapter should help the student to:

• Describe the structure, function, and location of the islets of Langerhans; the pineal body; and the adrenal, thyroid, and parathyroid glands.
  
• Describe the embryonic origin of the adrenal cortex, adrenal medulla, and thyroid and parathyroid glands.
  
• Describe the nerve and blood supply to the adrenal glands, islets of Langerhans, thyroid gland, and pineal body.
  
• Name the hormones produced by the adrenal cortex, adrenal medulla, islets of Langerhans, thyroid and parathyroid glands, and pineal body; for each hormone, identify the cell type responsible for its secretion, neural and endocrine regulating factors, and main targets and effects.
  
• Identify the capsule, cortex, zona glomerulosa, zona fasciculata, zona reticularis, medulla, chromaffin cells, and ganglion cells in a micrograph of the adrenal gland.
  
• Identify the islets of Langerhans in a micrograph of the pancreas.
  
• Trace the steps in the synthesis, storage, and secretion of hormones by the thyroid’s follicular cells.
  
• Identify the follicles, follicular cells, basement membrane, colloid, capillaries, and parafollicular cells in a micrograph of the thyroid gland.
  
• Identify the capsule, chief cells, and oxyphil cells in a micrograph of the parathyroid gland.
  
• Identify pinealocytes, astroglial cells, and brain sand (corpora arenacea) in a micrograph of the pineal body.

1. Compare the adrenal cortex and medulla in terms of their embryonic origins (II.A.1 and B.1).

2. Trace the path taken by the blood supplying the adrenal capsule, cortex, and medulla (II.C.1–4).

3. Name the layers of the adrenal cortex, beginning with the layer closest to the capsule (II.A.2.a–c). Compare them in terms of the structure and arrangement of their secretory cells and the classes and examples of hormones secreted by each layer.

4. Compare glucocorticoids, mineralocorticoids, and adrenal androgens (II.A.3.a–c) in terms of sites of synthesis, target organs and effects, and factors that stimulate or inhibit their production.

5. Describe the fetal (provisional) cortex (II.A.5) in terms of:

1. 
   

   Size and location

   
   
2. 
   

   Number of layers

   
   
3. 
   

   Age when involution begins

   
   
4. 
   

   Function

6. Name the adrenal medulla’s two major cell types (II.B.2.a and b).

7. Name the two major catecholamines secreted by the adrenal medulla (II.B.3).

8. Describe the factors leading to and the consequences of increased catecholamine secretion by the adrenal medulla (II.B.2.a, b, and 3).

9. Give the location of the islets of Langerhans (III).

10. Name four major hormone-secreting cells in the islets of Langerhans (III.A–D) and compare them in terms of their location (peripheral or central), abundance, and secretory granules and the hormones they produce. Compare the hormones produced in terms of the factors that stimulate their secretion, their targets, and their effects.

11. Describe the thyroid gland in terms of its location, number of lobes, and embryonic origin (IV) and the hormones it secretes (IV.A.2 and C).

12. Sketch a section through three thyroid follicles and the intervening tissue (Fig. 21–1). Label the follicle (epithelial) cells, basal lamina, colloid, capillaries, and parafollicular cells.

13. On the drawing for question 12, show the site of:

1. 
   

   Thyroglobulin storage (IV.B.2.a)

   
   
2. 
   

   Tyrosine residue iodination (IV.B.2.c)

   
   
3. 
   

   Iodide oxidation (IV.B.2.b)

   
   
4. 
   

   Thyroglobulin synthesis (IV.B.2.a)

   
   
5. 
   

   Calcitonin synthesis (IV.C)

   
   
6. 
   

   The iodide pump (IV.B.2.b)

   
   
7. 
   

   Cleavage of T3 and T4 from iodinated thyroglobulin (IV.B.2.d)

   
   
8. 
   

   Release of T3 and T4 from follicular cells (IV.B.2.d)

14. Describe the effects of TSH on thyroid follicles in terms of follicle cell size and shape (IV.B.1), follicle diameter (IV.A), thyroglobulin synthesis (IV.B.2), iodide uptake (IV.B.2.b), pinocytosis of colloid (IV.B.2.d), and thyroxine production (IV.B.2).

15. List the steps in the synthesis, storage, and iodination of thyroglobulin, naming all intracellular and extracellular components involved (IV.B.2.a–c).

16. Beginning with the uptake of iodinated thyroglobulin, list the steps leading to the release of T3 and T4 from the follicular cell and name the organelles involved in each step (IV.B.2.d).

17. Describe parafollicular cells (IV.C) in terms of staining properties, location, hormones secreted and factor(s) that stimulate their secretion, and the targets and effects of their hormones.

18. Describe the parathyroid glands in terms of their number (V), dimensions (V.A.1), location (V), embryonic origin (V), and the major hormone they produce (V.A.2).

19. Name the two major parenchymal cells in human parathyroid glands and compare them in terms of their relative number, diameter, staining properties, secretory products, and the number of mitochondria they contain (V.A and B).

20. Describe parathyroid hormone in terms of:

1. 
   

   The cell that secretes it (V.A.2)

   
   
2. 
   

   Stimulus required for secretion (V.A.2)

   
   
3. 
   

   Effect on blood calcium (V.A.2)

   
   
4. 
   

   Effect on blood phosphate (V.A.2)

   
   
5. 
   

   Three main targets and effects on each (V.A.2)

   
   
6. 
   

   Effect of high blood calcium on secretion (V.A.2)

   
   
7. 
   

   Opposing hormone (IV.C)

21. Describe the pineal body (VI) in terms of:

1. 
   

   Shape and dimensions

   
   
2. 
   

   Location

   
   
3. 
   

   Covering tissue

   
   
4. 
   

   Principal cell types

   
   
5. 
   

   Calcified bodies

   
   
6. 
   

   Principal hormone produced