Endocrine Organ

Question 1

Parenchyma

Answer 1

Cords/clumps of hormone-producing cells

Question 2

Common feature sof endocrine organs

Answer 2

• Parenchyma secretes hormones:
  
  • Peptides
  • Aa derivatives
  • Steroids
• Fenestrated capillaries
• Ductless glands (unlike exocrine)
• Stroma: reticular connective tissue
  
  • ^{Fibroblasts, nerves, immune cells, etc}

Question 3

Neuroendocrine cells

Answer 3

Morphology & function of a neuron, but ends on a blood vessel.

Secretes neurohormones

Question 4

Hormone over production

Answer 4

• Increased # of cells (Graves’ disease)
• Increased hormone synthesis/release (genetic changes)

Ex) Pituitary adenoma - benign proliferation of the pituitary

Question 5

Hormone udnerproduction

Answer 5

• Disease or autoimmunity destroys an endocrine organ
  
  • Ex) Tuberculosis, Hasimoto’s
• Genetic abnormalities
  
  • Ex) Hypogonadism
• Abnormal hormone synthesis
  
  • Ex) GH gene deletion
• Abnormal secretion
  
  • ​Ex) Thyroidectomy

Question 6

Tumors of endocrine glands can cause…

Answer 6

Hormone over production

OR

Compress/destroy othe rorgans

Question 7

Altered tissue responses to hormones are the result of

Answer 7

receptor mutations (TSH, LH, PTH, and steroid receptors)

Question 8

Other than the glands, where else do you see endocrine tissue?

Answer 8

Digestive tract

Kidneys

Gonads

Placenta

Question 9

Hypophysis (pituitary gland) divisions, tissue type, embryologic origin

Answer 9

• Adenohypophysis (anterior lobe)
  
  • ​glandular tissue
  • ectoderm from roof of mouth
  • Pars distalis, Pars tuberalis, Pars intermedia
• Neurophypophysis (posterior lobe)
  
  • ​neural secretory tissue
  • ectoderm from floor of brain
  • Median eminence, Infundibulum, Pars Nervosa

Question 10

What do the arrows point at?

Answer 10

Rathke’s pouch

Question 11

Which belongs to the neurohypophysis?

Answer 11

Pars Nervosa

Question 12

Pars distalis vs Pars nervosa histological difference

Answer 12

Pars distalis is glandular tissue, so there are a lot of epithelial-derived cuboidal cells –> way more nuclei

Question 13

What cells do you see in the hypothalamus vs the pars distalis vs the pars nervosa?

Answer 13

Hypothalamus - neuroendocrine cells’ cell body

Pars distalis - endocrine cells

Pars nervosa - no hormone-producing cells; just the axons of the neuroendocrine cells of the hypothalamus

Question 14

What are the 4 regions of the hypothalamus?

Answer 14

Paraventricular nucleus

Supraoptic nucleus

Medial preoptic nucleus

Arcuate nucleus

Question 15

Describe the cells of the pars distalis

Answer 15

• Chromophils - secreting secretory granules of hormones into those fenestrated capillaries (pictured)
  
  • ​Acidophils (pink in h&e; orange in pas-orange)
  • Basophis (blue in h&e; purple in pas-orange)
• Chromophobes
• Folliculostellate cells - unknown function

Question 16

This is a PAS-orange G stain of the pars distalis. What are the purple cells? What are the orange cells?

Answer 16

Question 17

What do acidophils of the pars distalis release?

Answer 17

Somatotrophs - growth hormone

Mammotrophs/lactotrophs- prolactin

Question 18

What do basophils of the pars distalis release?

Answer 18

Thyrotrophs - TSH

Gonadotrophs - FSH & LH

Corticotrophs - ACTH

Question 19

What nucleus of the hypothalamus is the only oen that DOESN’T release hypothalamic releasing or inhibiting factors?

Answer 19

Supraoptic.

Question 20

What are the hypothalamic releasing & inhibiting factors/hormones for TSH, prolactin, FSH&LH, ACTH, and GH?

Answer 20

• TSH
  
  • TRH +
  • Somatostatin -
• Prolactin
  
  • TRH +
  • Dopamine -
• FSH & LH
  
  • GnRH +
• ACTH
  
  • CRH +
• GH
  
  • GHRH +
  • Somatostatin+

Question 21

Hypothalamohypophyseal Portal system

Answer 21

Concentrates & directs hypothalamic hormones directly to the pituitary before entering general circulation; _{keeps these hormones (whcih are effective in miniscular amts) localized}

• Hormones released into the superior hypophyseal arteryperfuses the hypothalamus, which opens into theprimary capillary plexus
• Shunted to the pars distalis via the hypophyseal portal veins
• Enters the secondary capillary plexus
• Drained by hypophyseal veins

Question 22

Pars intermedia

Answer 22

• Cuboidal cells and colloid containing cysts (remnant of Rathke’s pouch) between the pars distalis & pars nervosa
• Secretes MSH (melanocyte stimulating hormone)
  
  • _{Function in humans isn’t understood; stimulates melanin production in lower animals}

Question 23

Which nuclei of the hypothalamus release hormones to the pars nervosa?

What hormones are they releasing?

Answer 23

Paraventricular & Supraoptic

• Oxytocin & ADH
  
  • synthesized by separate neuroendocrine cells whose cell bodies are located in both the PVN & SON
  • sent directly down an unmyelinated axon into the pars nervosa
    
    • Note: no releasing or inhibiting factors like in the pars distalis

Question 24

Features of neurohypophysis/pars nervosa

Answer 24

• Herring bodies - neurosecretory vesicles at nerve endings
• Pituicytes - supporting cells; NOT hormone-producing
• Capillaries

Question 25

What is this a slide of?

Answer 25

Neurohypophysis / pars nervosa

Question 26

You could find ADH in the ___ of the hypothalamus and in the ___ of the neurohypophysis.

Answer 26

**PVN** of hypothalamus **Herring bodies** of neurohypophysis

Question 27

Pineal gland structure/stroma

Answer 27

* **Connective tissue capsule & septae** divides gland into lobules * **Fenestrated capillaries** * **Corpora arenacea** ("brain sand"): calcified concretions

Question 28

What is the dark area?

Answer 28

brain sand

Question 29

main cells of the pineal gland

Answer 29

**Pinealocytes (**90%) - arranged in clumps; produces melatonin during dark periods **Interstitial cells:** glial like cells; supportive

Question 30

**Melatonin** is secreted during dark periods Other than its maintenance of circadian rhythms, what else does it do?

Answer 30

* **Antigonadal effects** * **​**Tumors that destroy the pineal --\> precocious puberty in children * Contraceptive properties in humans * **Antiproliferative effects** on breast & prostate cancers

Question 31

Regulation of melatonin secretion

Answer 31

Light in the eyes innervates postganglionic sympathetics from **superior cervical ganglion** -\> axons **synapse on the pinealocytes** and control melatonin production

Question 32

Thyroid gland structure

Answer 32

* Bilobed with isthmus * Fibroelastic connective tissue capsule and septae * Stroma: reticular cells & reticular fibers * Fenestrated capillaries * Has 4 parathyroids on top of it.

Question 33

2 main cells of the thyroid and what they secrete

Answer 33

**Follicular cells**: thyroid hormones **Parafollicular cells** (0.1%): calcitonin

Question 34

**Colloid**

Answer 34

gel-like mass containing **thyroglobulin** (Storage form of thyroid hormone) Surrounded by follicular cells

Question 35

What is going on in this slide? Identify what the arrows are pointing to Identify the white bubbles

Answer 35

Follicular cells (cuboidal epithelial cells) makign T3/T4 hormone are also releasing thyroglobulin (white bubbles) into the colloid Arrows = capillaries

Question 36

What is this? Where are the receptors? Whats the basal and apical side?

Answer 36

Follicular cell releasing into colloid Basal side faces the capillary lumen; Apical side faces the colloid **Receptors for hormones are on the basal side!**

Question 37

Where are parafollicular cells?

Answer 37

Between follicular cells

Question 38

Is this a parafollicular or a follicular cell?

Answer 38

parafollicular because lots granules