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Semester 5 April > Histology - Endocrine System > Flashcards

Histology - Endocrine System Flashcards

0
Q

Egs of peptide hormones

A

Glycoproteins -> TSH, LH, FSH

Short polypeptides -> ADH, Oxytocin, Prolactin, GH

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1
Q

Egs of amino acid derived hormones

A

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

Tryptophan -> melatonin

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2
Q

Egs of lipid derived hormones

A

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

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3
Q

Routes of communication in endocrine system

A

Endocrine
Paracrine
Autocrine
Synaptic

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4
Q

Features of endocrine system

A

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

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5
Q

How are islet cell types identified

A

Cell distribution
Immunohistochemistry/ flourescence
EM

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6
Q

Two vascular systems in the pancreas

A

Insuloacinar portal system

Acinar vascular system

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7
Q

How are islet cells regulated

A
  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)
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8
Q

Alpha cells release

A

Glucagon

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9
Q

Beta cells release

A

Insulin

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10
Q

Delta cells release

A

Somatostatin and gastrin

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11
Q

F-cells release

A

Pancreatic polypeptide

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12
Q

When are D cells stimulated

A

After protein rich meal

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13
Q

What hypothalamic nuclei releases ADH

A

Supra optic nucleus

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14
Q

What hypothalamic nuclei release OXY

A

Para ventricular nucleus

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15
Q

How is the pituitary formed

A

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

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16
Q

What separates the two lobes of the pituitary

A

Pars intermedia

17
Q

What are the separate parts of the pituitary

A 
Infundibular stem
Pars tuberalis
Pars distalis (anterior)
Pars intermedia (Rathke's cyst)
Pars nervosa (posterior)
18
Q

Blood supply to pituitary

A

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

Note inferior hypophyseal artery supplies pars nervosa

19
Q

Function of hypothalamo-hypophyseal portal system

A
  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
20
Q

Three components of anterior pituitary

A

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

21
Q

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

A

Somatotrophs (GH - somatotropin)

Lactotrophs (Prolactin)

22
Q

Somatotrophs inhibited by … and stimulated by …

A

Somatostatin. Increased blood glucose.

GHRH. Decreased IGF-1.

23
Q

Function of GH

A

Stimulate secretion of IGF-1 by liver

24
Q

Lactotrophs inhibited by … and stimulated by …

A

Dopamine

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

25
Q

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

A

Gonadotrophs - FSH, LH
Thyrotrophs - TSH
Corticotrophs - ACTH

26
Q

What is the role of pituicytes in the release of hormones

A

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

27
Q

Absence of thyroid leads to what childhood feature

A

Cretinism

28
Q

Morphology of hypothyroid gland

A

Large colloid filled follicles
Flattened principle cells
Sparse resorption vacuoles

29
Q

Morphology of hyperthyroid

A

Numerous small irregular shaped follicles
Columnar principle cells
Many resorption vacuoles

30
Q

Function of C cells in thyroid

A

Release calcitonin to suppress Ca resorption from bone.

31
Q

Describe exocrine phase of thyroid hormone synthesis

A

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

32
Q

Describe the endocrine phase of thyroid hormone synthesis

A

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

33
Q

What will removal of the parathyroid glands cause

A

Tetany

Thoracic and laryngeal muscle spasm = death

34
Q

What does PTH do

A

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

35
Q

Functional cells of the parathyroid gland

A

Chief cells

Oxyphil cells

36
Q

What can be seen on EM of a steroid cell

A

Lipid droplets
Mitochondria ++
Abundant sER

37
Q

General steroid synthesis path way

A

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

38
Q

Blood supply to adrenal gland

A

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

39
Q

Mechanism of hot flashes

A

High GnRH, FSF, LH

Low estrogen

40
Q

What happens following estrogen withdrawal

A 
Vasomotor disturbances
Atrophy vaginal epithelium
Decreased vaginal secretions
Decreased circulation to vagina/ uterus
Loss of vaginal tone (pelvic relaxation)
Cardiovascular risk increased
41
Q

Why does increased fat help in menopause

A

Androstenedione and DHEA can be converted to estrone by adipose tissue

Semester 5 April (17 decks)

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