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Histo > Endocrine Organs > Flashcards

Endocrine Organs Flashcards

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
Q

What is the dark area?

A

brain sand

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34
Q

Colloid

A

gel-like mass containing thyroglobulin (Storage form of thyroid hormone)

Surrounded by follicular cells

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35
Q

What is going on in this slide?

Identify what the arrows are pointing to

Identify the white bubbles

A

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

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36
Q

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

A

Follicular cell releasing into colloid

Basal side faces the capillary lumen; Apical side faces the colloid

Receptors for hormones are on the basal side!

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37
Q

Where are parafollicular cells?

A

Between follicular cells

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38
Q

Is this a parafollicular or a follicular cell?

A

parafollicular because lots granules

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41
Q

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

A

Supraoptic.

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45
Q

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

What hormones are they releasing?

A

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
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48
Q

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

A

PVN of hypothalamus

Herring bodies of neurohypophysis

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51
Q

main cells of the pineal gland

A

Pinealocytes (90%) - arranged in clumps; produces melatonin during dark periods

Interstitial cells: glial like cells; supportive

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52
Q

Melatonin is secreted during dark periods

Other than its maintenance of circadian rhythms, what else does it do?

A
  • Antigonadal effects
    • ​Tumors that destroy the pineal –> precocious puberty in children
    • Contraceptive properties in humans
  • Antiproliferative effects on breast & prostate cancers
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53
Q

Regulation of melatonin secretion

A

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

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54
Q

Thyroid gland structure

A
  • Bilobed with isthmus
  • Fibroelastic connective tissue capsule and septae
  • Stroma: reticular cells & reticular fibers
  • Fenestrated capillaries
  • Has 4 parathyroids on top of it.
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55
Q

2 main cells of the thyroid

what do they secrete?

what do the secretions do?

A

Follicular cells: thyroid hormones/thyroxine (T3 and T4) regulates tissue basal metabolism

Parafollicular cells (0.1%): calcitonin decreases blood calcium

56
Q

What is being secreted by the arrowed cell?

What else might you see in this area?

A

Parafollicular cell secretes calcitonin

Fenestrated capillaries, fibroblasts, connective tissue, immune cells

57
Q

Unlike other endocrine glands, the precursor hormone of the thyroid….

A

Thyroglobulin is stored extracellularly

58
Q

What regulated T3 & T4 secretion?

A

TRH - hypothalamic factor that stimulates thyrotrophs of the pars distalis to release TSH

59
Q

How does TSH induce T3 & T4 release?

A

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
Q

General steps of T3 and T4 release after TSH has bound its receptor and caused [cAMP] increase

A
  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
Q

Graves disease

A

Hyperthyroidism (autoimmune)

Goiter produces autoantibodies that can stimulate the TSH receptor enough to increase cAMP and cause increased T3 & T4 synthesis

62
Q

Secondary hyperthyroidism

A

TSH adenoma (originates from thyrotrophs) in the adenohypophysis

63
Q

Hashimoto thyroiditis (HT)

A

Goiter produces thyroid peroxidase autoantibodies, which destroy this enzyme needed for thyroid synthesis.

64
Q

Primary hypothyroidism (PH)

A

TSH receptor-blocking autoantibodies are present

65
Q

Secondary hypothyroidism

A

Low TSH secretion from the adenohypophysis

or

Low TRF secretion from hypothalamus

66
Q

Calcitonin is secreted in response to __

What are its effects?

A

Secreted in response to high blood [Ca2+]

  • Reduces blood calcium by
    • inhibiting osteoclasts (reducing bone resorption)
    • promoting kidney excretion of Ca2+ & phosphate
67
Q

Structure of parathryoid

A

4 ovoid glands on posterior surface of thyroid

  • Connective tissue capsule and trabeculae
  • Stroma: reticular cells and fibers
  • Fenestrated capillaries
68
Q

Cells of the parathyroid gland

A
  • Chief cells: produces parathyroid hormone
  • Oxyphils: unknown function; large, eosinophilic
  • Adipocytes: ~50% in older individuals
69
Q

Parathyroid hormone (PTH) actions

A

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
Q

How to differentiate between chief cells and oxyphils of parathyroid?

A

Chief cells (PTH-producing) are darker than oxyphils

71
Q

Primary hypoparathyroidism

What is it and what are th symptoms?

A

Deficient PTH secretion (accidental damage, hereditary, autoimmune)

  • Very dense bones
  • Spastic muscle contractions, convulsions, tetany, deaht
72
Q

Pseudohypoparathyroidism

A

Abnormal PTH receptors cause hypocalcemia

73
Q

Primary hyperparathyroidism

A

hormone-secreting chief cell tumor

  • thin bones, bone fractures
  • bone deposits in soft tissue
74
Q

Malignant tumors (e.g. breast, lung, ovarian) may secrete

A

PTH-related protein (PTHrP) –> hypercalcemia

75
Q

Pancreatic islets release what 4 endocrine hormones?

A

Insulin

Glucagon

Somatostatin

Pancreatic polypeptide

This is not GI - they’re released into the <em>blood, not the duct</em>

76
Q

Pancreatic islet structure

A
  • 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
Q

Silver staining of a pancreatic islet will react with ___ to showcase the ___.

A

Reacts with glucagon to show the A cells at the periphery

78
Q

Locations and hromones of the islet cells

A

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
Q

T1D vs T2D

A
  • 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
Q

What disease is this?

81
Q

What disease is this?

A

Beta cells replaced by fibrotic-looking, proteinacious amyloid deposits

82
Q

Adrenal glands - where are they and describe the strucutre

A

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
Q

Cortex & Medulla

What ‘-derm’ are they derived from?

What do they secrete?

A
  • Cortex
    • Mesoderm-derived
    • Secretes steroid hormones
  • Medulla
    • Neural crest ectoderm-derived
    • Secretes catecholamines; related to sympathetic nervous system
84
Q

Identify the different zones of this adrenal gland cortex.

85
Q

How to distinguish between the different zones of the cortex and the medulla?

A

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
Q

What zone is this

A

zona glomerulusa - globs by the capsule

87
Q

What zone is this

A

2 cell-wide vertical chords

88
Q

What hormones do the different zones of the cortex and the medulla secrete?

A
  • Zona glomerulosa - mineralocorticoids
    • Aldosterone
  • Zona fasciculata - glucocorticoids
    • ​Cortisol & corticosterone
  • Zona reticularis - weak androgens & some glucocorticoids
    • Dehydroepiandrosterone & androsterone
  • Medulla
    • ​Epinephrine
    • Norepinephrine
89
Q

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?

A

Cortex

Mineralocorticoids (Aldosterone)

Glucocorticoids (cortisol & corticosterone)

Sex steroids (weak androgens)

90
Q

Aldosterone - fxn & regulation

Cortisol - fxn & regulation

Dehydroepiandrosterone & androstenedione - regulation

A
  • 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
Q

Primary hyperaldosteronism/ Conn syndrome

A

Aldosterone-secreting adenoma

92
Q

Cushing syndrome

A

Commonly caused by administration of large doses of steroid to treat primary disease

OR

ACTH-secreting adenoma or adrenal cortical adenoma

93
Q

Congenital adrenal hyperplasia

A

Mutations in genes for steroid-synthesizing enzymes (21 hydroxylase, 11B-hydroxylase)

–> high androgens

94
Q

Addison’s disease (primary adrenal insufficiency)

A

Autoimmune destruction of adrenal cortex

95
Q

Secondary adrenal insufficiency

A

Hypothalamus or adenohypophysis disorder –> reduced ACTH

96
Q

Chromaffin cells

  • what is it
  • what does it secrete
  • what regulates its secretion
A

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
Q

Chromaffin cells secreting __ have larger granules

A

norepinephrine

98
Q

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
Q

Pheochromocytoma

A

catehcolamine producing tumor of adrenal medulla

100
Q

Neuroblastoma

A

Neoplasma containing primitive neuroblasts (40% occur in adrenal medulla)

101
Q

Vascular arrangement of adrenal gland

A

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
Q

Importance of the vascular arrangement of adrenal gland

A

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
Q

What is this

104
Q

What is this

105
Q

What are these?

106
Q

What gland is this

107
Q

What kind of hormoens are secreted here?

A

Steroids - this is only ZG & ZF, not medulla

108
Q

What is this? what are the arrows?

110
Q

A squamous follicular cell is ___

A cuboidal follicular cell is ___

A

Squamous = inactive

Cuboidal = active

Histo (20 decks)

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