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Endocrine Organs Flashcards

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1
Q

Parenchyma

A

Cords/clumps of hormone-producing cells

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2
Q

Common feature sof endocrine organs

A
  • 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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3
Q

Neuroendocrine cells

A

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

Secretes neurohormones

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4
Q

Hormone over production

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

Ex) Pituitary adenoma - benign proliferation of the pituitary

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5
Q

Hormone udnerproduction

A
  • 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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6
Q

Tumors of endocrine glands can cause…

A

Hormone over production

OR

Compress/destroy othe rorgans

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7
Q

Altered tissue responses to hormones are the result of

A

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

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8
Q

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

A

Digestive tract

Kidneys

Gonads

Placenta

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9
Q

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

A
  • 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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10
Q

What do the arrows point at?

A

Rathke’s pouch

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11
Q

Which belongs to the neurohypophysis?

A

Pars Nervosa

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12
Q

Pars distalis vs Pars nervosa histological difference

A

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

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13
Q

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

A

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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14
Q

What are the 4 regions of the hypothalamus?

A

Paraventricular nucleus

Supraoptic nucleus

Medial preoptic nucleus

Arcuate nucleus

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15
Q

Describe the cells of the pars distalis

A
  • 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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16
Q

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

A
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17
Q

What do acidophils of the pars distalis release?

A

Somatotrophs - growth hormone

Mammotrophs/lactotrophs- prolactin

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18
Q

What do basophils of the pars distalis release?

A

Thyrotrophs - TSH

Gonadotrophs - FSH & LH

Corticotrophs - ACTH

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20
Q

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

A
  • TSH
    • TRH +
    • Somatostatin -
  • Prolactin
    • TRH +
    • Dopamine -
  • FSH & LH
    • GnRH +
  • ACTH
    • CRH +
  • GH
    • GHRH +
    • Somatostatin-
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21
Q

Hypothalamohypophyseal Portal system

A

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
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22
Q

Pars intermedia

A
  • 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
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24
Q

Features of neurohypophysis/pars nervosa

A
  • Herring bodies - neurosecretory vesicles at nerve endings
  • Pituicytes - supporting cells; NOT hormone-producing
  • Capillaries
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25
Q

What is this a slide of?

A

Neurohypophysis / pars nervosa

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27
Q

Pineal gland structure/stroma

A
  • Connective tissue capsule & septae divides gland into lobules
  • Fenestrated capillaries
  • Corpora arenacea (“brain sand”): calcified concretions
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28
What is the dark area?
brain sand
34
**Colloid**
gel-like mass containing **thyroglobulin** (Storage form of thyroid hormone) Surrounded by follicular cells
35
What is going on in this slide? Identify what the arrows are pointing to Identify the white bubbles
Follicular cells (cuboidal epithelial cells) are releasing thyroglobulin (white bubbles) into the colloid; at the border, T3 & T4 are being synthesized on the thyroglobulin. Arrows = capillaries
36
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!**
37
Where are parafollicular cells?
Between follicular cells
38
Is this a parafollicular or a follicular cell?
parafollicular because lots granules
41
What nucleus of the hypothalamus is the only oen that DOESN'T release **hypothalamic releasing or inhibiting factors**?
Supraoptic.
45
Which nuclei of the hypothalamus release hormones to the pars nervosa? What hormones are they releasing?
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
48
You could find ADH in the ___ of the hypothalamus and in the ___ of the neurohypophysis.
**PVN** of hypothalamus **Herring bodies** of neurohypophysis
51
main cells of the pineal gland
**Pinealocytes (**90%) - arranged in clumps; produces melatonin during dark periods **Interstitial cells:** glial like cells; supportive
52
**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
53
Regulation of melatonin secretion
Light in the eyes innervates postganglionic sympathetics from **superior cervical ganglion** -\> axons **synapse on the pinealocytes** and control melatonin production
54
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.
55
2 main cells of the thyroid what do they secrete? what do the secretions do?
**Follicular cells**: thyroid hormones/thyroxine (T3 and T4) regulates tissue basal metabolism **Parafollicular cells** (0.1%): calcitonin decreases blood calcium
56
What is being secreted by the arrowed cell? What else might you see in this area?
Parafollicular cell secretes calcitonin Fenestrated capillaries, fibroblasts, connective tissue, immune cells
57
Unlike other endocrine glands, the precursor hormone of the thyroid....
**Thyroglobulin is stored extracellularly**
58
What regulated T3 & T4 secretion?
**TRH** - hypothalamic factor that stimulates thyrotrophs of the pars distalis to release TSH
59
*How* does TSH induce T3 & T4 release?
it stimulates all steps of T3 & T4 synthesis and release via **cAMP:** When it binds to its receptor on the basal side of a follicular cell, it activates adenylate cyclase
60
General steps of T3 and T4 release after TSH has bound its receptor and caused [cAMP] increase
1. Synthesize thyroglublin 2. Uptake of iodide and oxidation into iodine 3. Iodination of thyroglobulin to MIT/DIT in colloid 4. Formation of T3 & T4 5. Endocytosis and degradation of T3/T4 (modified tyrosines) 6. Release of free T3/T4 back across the basal side
61
Graves disease
Hyperthyroidism (autoimmune) ## Footnote Goiter produces autoantibodies that can stimulate the TSH receptor enough to increase cAMP and cause increased T3 & T4 synthesis
62
Secondary hyperthyroidism
TSH adenoma (originates from thyrotrophs) in the adenohypophysis
63
Hashimoto thyroiditis (HT)
Goiter produces **thyroid peroxidase autoantibodies,** which destroy this enzyme needed for thyroid synthesis.
64
Primary hypothyroidism (PH)
TSH receptor-*blocking* autoantibodies are present
65
Secondary hypothyroidism
Low TSH secretion from the adenohypophysis or Low TRF secretion from hypothalamus
66
**Calcitonin** is secreted in response to \_\_ What are its effects?
Secreted in response to **high blood [Ca2+]** * Reduces blood calcium by * **inhibiting osteoclasts** (reducing bone resorption) * **promoting kidney excretion of Ca2+ & phosphate**
67
Structure of parathryoid
4 ovoid glands on posterior surface of thyroid * **Connective tissue capsule and trabeculae** * **Stroma:** reticular cells and fibers * **Fenestrated capillaries**
68
Cells of the parathyroid gland
* **Chief cells**: produces parathyroid hormone * **Oxyphils**: unknown function; large, eosinophilic * **Adipocytes:** ~50% in older individuals
69
Parathyroid hormone (PTH) actions
Increases blood [Ca2+] by targeting * **Osteoblasts** to release RANK ligand--\> activates osteoclasts for bone resorption * -\> releases calcium * -\> increased serum alkaline phosphatase * **Kidney tubules:** * calcium reabsorption * phosphate excretion * vitamin D3 synthesis * **Small intestine** calcium absorption (requires vit D3)
70
How to differentiate between chief cells and oxyphils of parathyroid?
Chief cells (PTH-producing) are darker than oxyphils
71
Primary hypoparathyroidism What is it and what are th symptoms?
Deficient **PTH secretion** (accidental damage, hereditary, autoimmune) * Very dense bones * Spastic muscle contractions, convulsions, tetany, deaht
72
Pseudohypoparathyroidism
**Abnormal** **PTH receptors** cause hypocalcemia
73
Primary hyperparathyroidism
hormone-secreting chief cell tumor * thin bones, bone fractures * bone deposits in soft tissue
74
Malignant tumors (e.g. breast, lung, ovarian) may secrete
**PTH-related protein (PTHrP)** --\> hypercalcemia
75
Pancreatic islets release what 4 endocrine hormones?
Insulin Glucagon Somatostatin Pancreatic polypeptide This is not GI - they're released into the blood, not the duct
76
Pancreatic islet structure
* **Parenchyma**: islets (only 1-2% of pancreas) * 10% of islet cells are _autonomically innervated_ * Islet cells have _gap junctions_ * **Stroma:** reticular cells and reticular fibers * **Fenestrated capillaries**
77
Silver staining of a pancreatic islet will react with ___ to showcase the \_\_\_.
Reacts with **glucagon** to show the **A cells** at the periphery
78
Locations and hromones of the islet cells
**Alpha/A cells** (20%) - glucagon, periphery **Beta/B cells** (70%) - insulin, interior **Delta/D cells** (5%) - somatostatin, scattered **F cells** (\<1%) - pancreatic polypeptide (inhibits secretion from exocrine pancreas)
79
T1D vs T2D
* **Type 1 Diabetes -** ​Autoantibodies & lymphocytes kill beta cells * Decreased B cells * Lymphocytes present * **Type 2 Diabetes** - Insulin resistance in peripheral tissues & abnormal beta cell function * **Amyloid deposits** in islets *may* reduce # of beta cells
80
What disease is this?
81
What disease is this?
Beta cells replaced by fibrotic-looking, proteinacious amyloid deposits
82
**Adrenal glands** - where are they and describe the strucutre
Superior pole (on top of) of kidney * Dense ct **capsule** & trabeculae; stroma; fenestrated capillaries * **Cortex (90%)** * **​**Zona glomerulosa (outer) * Zona fasciculata * Zona reticularis (inner) * **Medulla (10%)**
83
Cortex & Medulla What '-derm' are they derived from? What do they secrete?
* Cortex * **Mesoderm-**derived * Secretes **steroid hormones** * Medulla * Neural crest **ectoderm**-derived * Secretes **catecholamines;** related to sympathetic nervous system
84
Identify the different zones of this adrenal gland cortex.
85
How to distinguish between the different zones of the cortex and the medulla?
**Zona glomerulosa** - globs by the capsule **Zona fasciculata** - two-cell ladders **Zona reticularis-** not like the ohter two **Medulla**- bigger cells that are on the inside
86
What zone is this
zona glomerulusa - globs by the capsule
87
What zone is this
2 cell-wide vertical chords
88
What hormones do the different zones of the cortex and the medulla secrete?
* **Zona glomerulosa** - mineralocorticoids * Aldosterone * **Zona fasciculata -** glucocorticoids * ​Cortisol & corticosterone * **Zona reticularis** - weak androgens & some glucocorticoids * Dehydroepiandrosterone & androsterone * **Medulla** * **​**Epinephrine * Norepinephrine
89
**Steroid-synthesizing cells** have abundant SER, miochondria, and lipid droplets\* What part of the adrenal gland is responsible for steroid hormone synthesis? What steroid hormones are produced?
**Cortex** Mineralocorticoids (Aldosterone) Glucocorticoids (cortisol & corticosterone) Sex steroids (weak androgens)
90
Aldosterone - fxn & regulation Cortisol - fxn & regulation Dehydroepiandrosterone & androstenedione - regulation
* **Aldosterone** * Targets kidney for regulation of fluid & electrolyte balance * Reg: Angiotensin II * **Cortisol** * Fxn: * Converts fat & muscle to glycogen * Regulate metabolism * Suppress immune system * Reg: ACTH, neg feedback by cortisol * **Dehydroepiandrosterone & androstenedione** * Reg: ACTH
91
**Primary hyperaldosteronism/ Conn syndrome**
Aldosterone-secreting adenoma
92
**Cushing syndrome**
Commonly caused by administration of large doses of steroid to treat primary disease OR ACTH-secreting adenoma or adrenal cortical adenoma
93
**Congenital adrenal hyperplasia**
Mutations in genes for steroid-synthesizing enzymes (21 hydroxylase, 11B-hydroxylase) --\> high androgens
94
**Addison's disease (primary adrenal insufficiency)**
Autoimmune destruction of adrenal cortex
95
**Secondary adrenal insufficiency**
Hypothalamus or adenohypophysis disorder --\> reduced ACTH
96
Chromaffin cells - what is it - what does it secrete - what regulates its secretion
modified postganglionic sympathetic neurons in the **adrenal medulla** that have lost dendrites and axons * Regulation: innervation by preganglionic sympathetic neurons * Secretes catecholamines - **epinephrine** (75%) and **norepinephrine** (25%) * Reinforce sympathetic nervous system during stress * Key defense against hypoglycemia
97
Chromaffin cells secreting __ have larger granules
norepinephrine
98
Recall that in the sympathetic nervous system, the preganglionic neuron will release ___ onto the postganglionic neuron, which will release ___ to motor nerves to smooth & cardiac muscle The adrenal medulla is just amodified sympathetic ganglia!
99
Pheochromocytoma
catehcolamine producing tumor of adrenal medulla
100
Neuroblastoma
Neoplasma containing primitive neuroblasts (40% occur in adrenal medulla)
101
Vascular arrangement of adrenal gland
**Short cortical arteries** get all their oxygen used up by the cortex such that by the time it makes it to the medulla, it's just venous blood **Long cortical arteries/medullary arteries** go straight into the medulla
102
Importance of the vascular arrangement of adrenal gland
Allows glucocorticoids from the adrenal cortex to make it to the medulla, where it's needed to convert norepinephrine to epinephrine and inhibit development of neuronal cell proceses
103
What is this
104
What is this
105
What are these?
106
What gland is this
107
What kind of hormoens are secreted here?
Steroids - this is only ZG & ZF, not medulla
108
What is this? what are the arrows?
109
110
A squamous follicular cell is \_\_\_ A cuboidal follicular cell is \_\_\_
Squamous = inactive Cuboidal = active

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