Histology - Endocrine System

Question 0

Egs of peptide hormones

Answer 0

Glycoproteins -> TSH, LH, FSH

Short polypeptides -> ADH, Oxytocin, Prolactin, GH

Question 1

Egs of amino acid derived hormones

Answer 1

Tyrosine -> thyroid hormone, catecholamines (E,NE,dopamine)

Tryptophan -> melatonin

Question 2

Egs of lipid derived hormones

Answer 2

Steroid -> androgens, estrogens, progestins, calcitriol, corticosteroids
Eicosanoids ->. Leukotrienes, prostaglandins

Question 3

Routes of communication in endocrine system

Answer 3

Endocrine
Paracrine
Autocrine
Synaptic

Question 4

Features of endocrine system

Answer 4

One gland many hormones
One hormone many glands
One hormone, many targets, many effects
One hormone different messenger type

Question 5

How are islet cell types identified

Answer 5

Cell distribution
Immunohistochemistry/ flourescence
EM

Question 6

Two vascular systems in the pancreas

Answer 6

Insuloacinar portal system

Acinar vascular system

Question 7

How are islet cells regulated

Answer 7

1. Neural - arteriole wall inner action regulates blood flow
2. Paracrine secretions - alpha cells regulate insulin release. Somatostatin inhibits insulin and glucagon release.
3. Autocrine - neoropeptide release that acts on same cell to release hormone (eg alpha cells release glutamate to stimulate glucagon release)

Question 8

Alpha cells release

Answer 8

Glucagon

Question 9

Beta cells release

Answer 9

Insulin

Question 10

Delta cells release

Answer 10

Somatostatin and gastrin

Question 11

F-cells release

Answer 11

Pancreatic polypeptide

Question 12

When are D cells stimulated

Answer 12

After protein rich meal

Question 13

What hypothalamic nuclei releases ADH

Answer 13

Supra optic nucleus

Question 14

What hypothalamic nuclei release OXY

Answer 14

Para ventricular nucleus

Question 15

How is the pituitary formed

Answer 15

Down growth of floor of diencephalon joins to Rathke’s pouch (up growth of ectodermal lining of future oral cavity)

Question 16

What separates the two lobes of the pituitary

Answer 16

Pars intermedia

Question 17

What are the separate parts of the pituitary

Answer 17

Infundibular stem
Pars tuberalis
Pars distalis (anterior)
Pars intermedia (Rathke's cyst)
Pars nervosa (posterior)

Question 18

Blood supply to pituitary

Answer 18

Superior hypophyseal artery -> 1ry cap plexus -> portal veins -> 2ndry cap plexus -> hypophyseal veins

Note inferior hypophyseal artery supplies pars nervosa

Question 19

Function of hypothalamo-hypophyseal portal system

Answer 19

1. Hormones from 1ry cap plexus can act on anterior hypophysis
2. Secretions from ant hypophysis can enter general circulation
3. Allows for functional integration of hypothalamus with anterior hypophysis

Question 20

Three components of anterior pituitary

Answer 20

Cords of epithelial cells (chromophils and chromophobes)
Delicate connective tissue stroma
Fenestrated caps

Question 21

What are the acidophilic cells in the ant pit lobe and what do they release

Answer 21

Somatotrophs (GH - somatotropin)

Lactotrophs (Prolactin)

Question 22

Somatotrophs inhibited by … and stimulated by …

Answer 22

Somatostatin. Increased blood glucose.

GHRH. Decreased IGF-1.

Question 23

Function of GH

Answer 23

Stimulate secretion of IGF-1 by liver

Question 24

Lactotrophs inhibited by ... and stimulated by ...

Answer 24

Dopamine Prolactin releasing hormone (PRH) thyrotropin releasing hormone (TRH)

Question 25

What are the basophilic cells in the ant pit lobe and what do they release

Answer 25

Gonadotrophs - FSH, LH Thyrotrophs - TSH Corticotrophs - ACTH

Question 26

What is the role of pituicytes in the release of hormones

Answer 26

They have retracting cell processes that allow passage of hormones into pericapillary space

Question 27

Absence of thyroid leads to what childhood feature

Answer 27

Cretinism

Question 28

Morphology of hypothyroid gland

Answer 28

Large colloid filled follicles Flattened principle cells Sparse resorption vacuoles

Question 29

Morphology of hyperthyroid

Answer 29

Numerous small irregular shaped follicles Columnar principle cells Many resorption vacuoles

Question 30

Function of C cells in thyroid

Answer 30

Release calcitonin to suppress Ca resorption from bone.

Question 31

Describe exocrine phase of thyroid hormone synthesis

Answer 31

Iodide diffuses across cell and is converted to iodine by thyroid peroxidase. Thyroglobulin is released into colloid and its tyrosyl residues are linked to two iodine molecules each = iodothyroglobulin

Question 32

Describe the endocrine phase of thyroid hormone synthesis

Answer 32

Iodothyroglobulin colloid droplet is endocytosed and fused with a lysosome. Proteolytic action of lysosomal enzymes release T3 and T4 which diffuse into the blood stream

Question 33

What will removal of the parathyroid glands cause

Answer 33

Tetany | Thoracic and laryngeal muscle spasm = death

Question 34

What does PTH do

Answer 34

Resort Ca from bone Stimulate kidney resorption of Ca Activate Vit D

Question 35

Functional cells of the parathyroid gland

Answer 35

Chief cells | Oxyphil cells

Question 36

What can be seen on EM of a steroid cell

Answer 36

Lipid droplets Mitochondria ++ Abundant sER

Question 37

General steroid synthesis path way

Answer 37

Cholesterol -> via StAR -> mitochondria -> sER -> mitochondria (not DHEA, androstenedione) -> extracellular

Question 38

Blood supply to adrenal gland

Answer 38

Capsular artery 1. Medullary arteriole 2. Cap bed in each zone Therefore dual blood supply

Question 39

Mechanism of hot flashes

Answer 39

High GnRH, FSF, LH | Low estrogen

Question 40

What happens following estrogen withdrawal

Answer 40

``` Vasomotor disturbances Atrophy vaginal epithelium Decreased vaginal secretions Decreased circulation to vagina/ uterus Loss of vaginal tone (pelvic relaxation) Cardiovascular risk increased ```

Question 41

Why does increased fat help in menopause

Answer 41

Androstenedione and DHEA can be converted to estrone by adipose tissue