14.1 - Endocrinology

Question 1

Pituitary Gland

Answer 1

= divided into 2 parts based on embryonic origin of its tissues

1) Neurohypophysis (posterior pituitary)
- is derived from neuroectoderm
- consists of the median eminence, infundibular stalk, pars nervosa
- contains descending axons that originated in the supraoptic and paraventricular nuclei of the hypothalamus
- descending axons release ADH and oxytocin
2) Adenohypophysis (anterior pituitary)
- derived from oral ectoderm
- forms donut-shaped ring around the infundibular stalk
- consists of: pars tuberalis, pars intermedia, pars distalis

Question 2

Neurohypophysis

Answer 2

= posterior pituitary

• derived from neuroectoderm
• consists of
  1) median eminence
  2) infundibular stalk
  3) pars nervosa
• contains descending axons that originate in the supraoptic and paraventricular nuclei of the hypothalamus
• dilated ends of axons from herring bodies –> release ADH and oxytocin
• resident glia cells = pituicytes

Question 3

Where do the descending axons of the neurohypophysis originate

Answer 3

• in the hypothalamic supraoptic and paraventricular nuclei

Question 4

Herring Bodies

Answer 4

= the dilated ends of the axons (descending from supra optic and paraventricular hypothalamic nuclei)
- release ADH and Oxytocin

Question 5

Pituicytes

Answer 5

= resident glia cells of the pituitary gland

Question 6

Adenohypophysis

Answer 6

= anterior pituitary

• derived from oral ectoderm
• forms a donut-shaped ring of tissue around the infundibular stalk - consists of:
  1) pars tuberalis
  2) pars intermedia
  3) pars distalis

Question 7

3 cell characterizations of the pars distalis

Answer 7

1) Acidophilis - producing:
a. growth hormone (somatotropin)
b. prolactin
2) Basophils - producing:
a. ACTH
b. TSH
c. FSH
d. LH
e. beta-endophin
3) chromophobes - not well understood

Question 8

Melanocyte-stimulating hormone (MSH)

Answer 8

• produced by cells of pars intermedia

Question 9

Thyroid gland

Answer 9

• contains numerous thyroid follicles = spherical accumulations of colloid composed of thyroglobulin contained by follicular cells with occasional interposed parafollicular cells (C-cells)

Question 10

Thyroid follicles

Answer 10

= spherical accumulations of colloid

Question 11

Colloid

Answer 11

• arranged in spherical accumulations called thyroid follicles
  = composed of thyroglobulin contained by follicular cells with occasional interposed parafollicular cells (C-cells)

Question 12

Thyroglobulin

Answer 12

• component of colloid
• colloid accumulates into spherical thyroid follicles
• is contained by follicular cells with occasional interposed parafollicular cells (C-cells)

Question 13

Follicular cells

Answer 13

• contain thyroglobulin
• produce T3 and T4
• component of colloid

Question 14

Parafollicular cells

Answer 14

= c-cells

• produce calcitonin
• component of colloid

Question 15

Parathyroid Gland

Answer 15

• majority cell type = chief cell –> produces PTH

- minority cell type = oxyphil –> unknown function

Question 16

Chief cell

Answer 16

= majority cell type in parathyroid glands

- produces parathormone (PTH)

Question 17

Oxyphil cell

Answer 17

= minority cell type in parathyroid gland

- unknown function

Question 18

Pineal Gland

Answer 18

• sits within the brain
• parenchymal cells = pinealocytes –> produce melatonin
• gland accumulates concretions = corpora arenacea = brain sand

Question 19

Pinealocytes

Answer 19

= parenchymal cells of the pineal gland

- produce melatonin

Question 20

Corpora arenacea

Answer 20

= concretion accumulations that occur in the pineal gland

- also called brain sand

Question 21

Pancreas

Answer 21

• contains groups of endocrine cells = islets of Langerhans
• 4 cell types in the islets (decreasing frequency)
  1) beta cells
• produce insulin
  2) alpha cells
• produce glucagon
  3) PP cells
• produce pancreatic polypeptide
  4) delta cells
• produce SST

Question 22

Islets of Langerhans

Answer 22

= groups of endocrine cells in the pancreas

• contain 4 cell types
  1) beta cells
  2) alpha cells
  3) PP cells
  4) delta cells

Question 23

Beta cells

Answer 23

• most frequent cell type in the islets of Langerhans in the pancreas
• produce insulin

Question 24

alpha cells

Answer 24

• second most frequent cell type in the islets of langerhans in the pancreas
• produce glucagon

Question 25

PP cells

Answer 25

= third most frequent cell type in the islets of Langerhans in the pancreas
- produce pancreatic polypeptide

Question 26

Delta cells

Answer 26

= fourth most frequent cell type in the islets of Langerhans in the pancreas
- produce SST

Question 27

Adrenal Gland

Answer 27

• consists of two embryologically distinct parts
  1) adrenal cortex
• produces corticosteroids
• organized into 3 layers:
  a. zona glomerulosa - mineralcorticoids (aldosterone)
  b. zona fasciculata - glucocorticoids (cortisol)
  c. zona reticularis - androgens
  2) adrenal medulla
• contains two types of chromatin cells
• producing epinephrie + NE

Question 28

Adrenal Cortex

Answer 28

• produces corticosteroids
• organized into 3 layers
  1) Zona glomerulosa
• produces mineralcorticoids
• primarily aldosterone
  2) Zona fasciculata
• produces glucocorticoids
• primarily cortisol
  3) Zona reticulata
• produces androgens

Question 29

Adrenal Medulla

Answer 29

• contains two types of chromatin cells

- they produce epinephrine + NE

Question 30

Diffuse neuroendocrine system (DNES)

Answer 30

= endocrine cells occurring as minority cell types in other endodermal-derived epithelia

• are particularly important to the control of the GI and respiratory systems
• many (but not all) secrete polypeptide hormone (e.x. CCK) from amine precursors using decarboxylase enzymes –> thus are known as amine precursor uptake and ecarboxylation cells (APUD)

Question 31

APUD cells

Answer 31

= amine precursor uptake and decarboxylation cells

- cells of the DNES that secrete polypeptide hormones from amine precursors (using decarboxylase enzymes)