Endocrine Organ Flashcards by Lauren Nguyen

Parenchyma

Cords/clumps of hormone-producing cells

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Common feature sof endocrine organs

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

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Neuroendocrine cells

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

Secretes neurohormones

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Hormone over production

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

Ex) Pituitary adenoma - benign proliferation of the pituitary

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Hormone udnerproduction

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

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Tumors of endocrine glands can cause…

Hormone over production

Compress/destroy othe rorgans

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Altered tissue responses to hormones are the result of

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

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

Digestive tract

Kidneys

Gonads

Placenta

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

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

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What do the arrows point at?

Rathke’s pouch

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Which belongs to the neurohypophysis?

Pars Nervosa

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Pars distalis vs Pars nervosa histological difference

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

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

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

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What are the 4 regions of the hypothalamus?

Paraventricular nucleus

Supraoptic nucleus

Medial preoptic nucleus

Arcuate nucleus

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Describe the cells of the pars distalis

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

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

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What do acidophils of the pars distalis release?

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Somatotrophs - growth hormone

Mammotrophs/lactotrophs- prolactin

What do basophils of the pars distalis release?

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Thyrotrophs - TSH

Gonadotrophs - FSH & LH

Corticotrophs - ACTH

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

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Supraoptic.

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

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

Hypothalamohypophyseal Portal system

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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

Pars intermedia

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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}

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

What hormones are they releasing?

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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

Features of neurohypophysis/pars nervosa

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

What is this a slide of?

Neurohypophysis / pars nervosa

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

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

Pineal gland structure/stroma

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

What is the dark area?

brain sand

main cells of the pineal gland

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

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

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

Regulation of melatonin secretion

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

Thyroid gland structure

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

2 main cells of the thyroid and what they secrete

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

**Colloid**

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

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

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

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

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

Where are parafollicular cells?

Between follicular cells

Is this a parafollicular or a follicular cell?

parafollicular because lots granules

Endocrine Organ Flashcards

(38 cards)