Micro-anatomy of the endocrine system

Question 1

describe the main histological features, connections, and embryological origins of the pituitary gland

Answer 1

• Hypophysis master gland ( grows underneath the hypothalamus)
• Hangs from hypothalamus with infundibular stalk
• NS and endocrine system linked :
  1) Anterior pituitary = adenohypophysis
  2) Posterior Pituitary =Neurohypophysis

Question 2

Describe the gross anatomical features of the thyroid gland

Answer 2

• Bilobed ( located on the anterior, lateral surface of the upper trachea)
• VVV vascular
• Parathyroids ( sit at the back, 2 on each side = regulate ca2+ levels )
• Goitre= swelling of the neck when they have abnormal functioning of the thyroid gland

Question 3

Describe the histological features of the adrenal glands

Answer 3

The most distinctive feature of the mammalian adrenal viewed at low magnification is its partitioning into cortex versus medulla.
Both tissues are very richly vascularized.
The adrenal cortex is partitioned into three concentric zones of steroid-synthesizing cells
- glomerulosa, fasiculata and reticularis.

Question 4

State the islets of Langerhans are the endocrine portions of the pancreas, and they form part of the Gastro-enteric pancreatic system (GEP)

Answer 4

-islands of the cell which help GEP
-Digestive function commuity
(population is subdivided )

Question 5

Embryological origin of the pituitary gland ***

Answer 5

1) Rathkes pouch ( extension of mouth )= ANTERIOR LOBE

2) Neuroectoderm = down growing of brain =Posterior lobe

Question 6

anterior / posterior pituitary parts
(5)
anterior =TID
posterior=IN

Answer 6

Anterior pituitary :

1-pars tuberalis
2-pars intermedia
3-pars distalis

Infundibulum connects both

posterior pituitary :
1-infundibular stalk
2-pars nervosa

Question 7

Histology of pituitary

Answer 7

1) Posterior pituitary= lighter

2) Anterior pituitary =darker because they make there own hormones

Question 8

Anterior pituitary
1)Histological classification
2)5 different types of cells
( for one of the cell types think Milk producing)

Answer 8

1) Chromophils ( BRIGHT)+ surrounded by capillaries:
- Acidophips (A)
- Basophils (B)

2)Chromophobes (c)
pale staining and quiet

5 types of anterior pituitary cells :

1) Somatotrophs =GH
2) Mammotrophs = prolactin
3) Corticotrophes = ACTH
4) Thyrotrophs =TSH
5) Gonatrophs=FSH/LH

Question 9

Posterior pituitary histology

• Staining
• Axons for ADH
• Axons for Oxytocin
• Cell types
• Vascular?

(4)

Answer 9

1-Pale staining and fibrous = nerve endings and unmyelinated axons
- axons for ADH =supraoptic nucleus
-axons for oxytocin=paraventicular nucleus
2- Herring Bodies = stores hormones
3-Pituicytes = support cells
4- highly Vascular

Question 10

Thyroid gland histology
(4)
2 main cell types

Answer 10

Spherical storage units called follicles :
Lined with thyroid epithelial cells= thyrocytes

1) Follicular cells = lined with microvilli: producing T3,T4, Regulates cell and tissue metabolic rate, growth and development
2) Parafollicular /C cells: make calcitonin = outside the follicle = calcitonin decreases blood ca2+, as they increase osteoclast activity, increasing bone resorption and bone formation

Question 11

What do follicular cells secrete?

4

Answer 11

1) glycoprotein called Thyroglobulin stored in the centre of the follicle as colloid

2) Thyroglobulin =inactive form of T3/T4
3) TSH stimulates this from thyrotrophes in anterior pituitary –>thryogolubuln broken down to T3, T4–>blood

Question 12

Adrenal gland

4

Answer 12

highly vascular gland surrounded by CT capsule

1) Cortex:
- Mineralocorticoids = zona glomerulosa
- glucocorticoids =zona fasiculata
- Androgens = zona reticularis

2)Medulla = neuronal crest cells = adrenaline and noradrenaline

Question 13

Histolgy of Adrenal cortex

3 zones what do the cells look like

Answer 13

1) Zona glomerulosa =rounded group of cells= mineralocorticoids
2) Zona fasciculata = much bigger cells, lipid droplets = produces glucocorticoids = under the control of ACTH
3) Zona reticularis =branching, an irregular network which produces androgens

Question 14

Pancreas has 4 types of cell ?

Answer 14

1) Alpha = glucagon
2) Beta = insulin
3) Delta cells=somatostatin
4) F cells=pp

Enteroendocrine cells :

Question 15

Enteroendocrine cells :
(4)
secrete hormones which control gut function
(4)

Answer 15

1) Gastrin = gastric acid secretion
2) Cholyecystokinin = CCK (bladder contraction)
3) Motilin= stimulates motility
4) Secretin = pancreatic enzyme and Gastric acid secretion