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HSF Block 3 > Histo - Endocrine I > Flashcards

Histo - Endocrine I Flashcards

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1
Q

What is the Hypothalamic‐Hypophyseal Axis?

A

Hypothalamus

  • NS interfaces w/ Endocrine system
  • Makes hormones for:
    1. causing release of pituitary hormones
    2. causing inhibition of release of pituitary hormones

Hypophysis (PITUITARY)

  • Sits in the Sella Turcica
    • depression in the sphenoid bone
  • Makes hormones for:
    1. Growth
    2. Reg of metabolism
    3. Ability to withstand stress
    4. Fluid balance
    5. Reproduction
    6. Lactation
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2
Q

What is the dev of the Pituitary?

A

Pituitary Gland Development

Basics:

  • Pars distalis & Pars tuberalis
    • come from ORAL ECTODERM
    • aka - RATHKE’S POUCH
  • Pars nervosa
    • comes from DIENCEPHALON
  • Pars intermedia
    • jxn btw the 2
    • site of: RATHKE’S CYSTS
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3
Q

What is this?

A

Pituitary Histology

Basics:

  • Pars distalis = basophilic area
  • Pars nervosa = eosinophilic area

Magnification:

  • Low
    • see stalk
  • High
    • Pars intermedia = colloid filled cyst
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4
Q

What is the structure of the Pituitary?

A

ANTERIOR PITUITARY (Adenohypophysis)

  1. Pars distalis
    • anterior lobe
  2. Pars tuberalis
  3. Pars intermedia
    • intermediate lobe
    • Rathke’s cyst
      • remnant of Rathke’s pouch
      • colloid filled vessels
        • simple cuboidal epithilium
  4. No blood/brain barrier
    • no direct blood supply

POSTERIOR PITUITARY (Neurohypophysis)

  1. Pars nervosa
    • neural tube
    • posterior lobe
  2. Infundibulum
    • infundibular process
    • median eminence
      • from hypothalamus
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5
Q

What is Hypothalamohypophysial Portal
Circulation?

A

HYPOTHALAMUS

  1. paraventricular nucleus
    • makes oxytocin
  2. supraoptic nucleus
    • makes ADH

PITUITARY:

  1. Anterior
    • Hypophyseal v.s. only
    • secondary plexus = hypothalamohypophysial Portal
      Circulation
      • primary plexus = stalk of Pituitary
  2. Posterior
    1. Inferior hypophyseal a. +
    2. hypophyseal v.s.
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6
Q

What are the 2 arteries that provide the blood supply for the pituitary?

A
  1. Superior hypophyseal a.s.
    • Supply = median eminance & infundibular stalk
    • Primary plexus of fenestrated capillaries
      • branch into secondary plexus (Posterior Pituitary)
        • hypothalamic-hyposeal portal circulation
    • carries releasing & inhibiting hormones to the PARS DISTALIS
  2. Inferior hypophyseal a.s.
    1. Supply = Posterior Pituitary
      1. no direct blood supply to PARS DISTALIS
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7
Q

What are the 5 parts of the Pituitary?

A
  1. Pars distalis (Posterior Pituitary)
    • acidophils/basophils/chromophobes
  2. Pars intermedia (In btw)
    • colloid w/ simple cuboidal cells
    • remnant of Rathke’s pouch
  3. Pars nervosa (Anterior Pituitary)
    • Herring bodies & pituicytes
      • store ADH & oxytocin
  4. Pars tuberalis
  5. Infundibular process
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8
Q

Chromophils vs Chromophobes

A

Chromophils

  • Acidophils
    • 40% of cells
    • eosinophilic
    • secrete PROTEIN hormones
  • Basophils
    • 10% of cells
    • Larger/Granulated
    • basophilic
    • secrete GLYCOPROTEIN hormones

Chromophobes

  • 50% of cells
  • do NOT stain
  • may be degranulated chromophils
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9
Q

What is this?

A

Acidophils

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10
Q

What is this?

A

Basophils

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11
Q

What is this?

A

Chromophobe

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12
Q

What is this?

A

Somatotrophs

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13
Q

What do Chromophils secrete?

A

Chromophils ‐ Secretions

Acidophils

  1. Somatotropin
    • GH - growth hormone
      • acts on body tissue/cartilage/muscle/bone/adipose
  2. Lactotrophs (mammotrophs)
    • PRL - prolactin
      • acts on mammary glands to stimulate milk production

Basophils

  1. Gonadotrophs
    • FSH - follicle stimulating hormone
    • LH - luteinizing hormone
      • both act on gonads to stimulate development
  2. Thyrotrophs
    • TSH - thyroid stimulating hormone
      • acts on thyroid to release thyroid hormone (TH)
  3. Corticotrophs
    • ACTH - corticotropin
      • acts on adrenal cortex to release corticosteriods
    • POMC - preopiomelanocortin
      • cleaved to make ACTH & Lipotrophic hormone
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14
Q

Hypophyseal regulatory hormones for the 5 cell types?

A
  1. Somatotroph (Somatotrophin)
    1. RH = Somatotrophin RH; Ghrelin (from stomach)
    2. IH = Somatostatin
  2. Lactotroph (Prolactin)
    1. RH = —; Oxytocin (from pars nervosa increases secretion)
    2. IH = dopamine
  3. Gonadotroph (FSH & LH)
    1. RH = FRH & LRH (GnRH)
    2. IH = —
  4. Thyrotroph (Thyrotropin)
    1. RH = Thyrotropin RH
    2. IH = Somatostatin
  5. Corticotroph (Corticotropin/ACTH)
    1. RH = Corticotropin RH
    2. IH = —
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15
Q
A
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16
Q

What is the Negative Feedback Loop for TSH & TRH?

A
  1. Stimulus (i.e. low body temp) causes hypothalamus to STIMULATE secrete thyrotropin-releasing hormone (TRH)
    • acts on anterior pituitary
  2. Thyrotropic cells in anterior pituitary release thyroid stimulating hormone (TSH)
  3. TSH stimulates the follicular cells of the thyroid gland to release thyroid hormone (TH)
  4. TH stimulates the target cells
    • increases metabolic activities –> increase in basal body temp
  5. Increase body temp is deteched by the hypothalamus
    • secretion of TRH is INHIBITED
    • TH blocks TRH receptors & inhibits synthesis of thyrotropic hormone
      • decrease production in the thyroid
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17
Q

What is this?

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A

Pars Intermedia

  • Remnants of Rathke’s pouch
    • present as colloid filled cysts
    • aka = RATHKE’S CYSTS
18
Q

What is this?

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A

Pars Intermedia

19
Q

What is this?

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A

Neurohypophysis

POSTERIOR PITUITARY:

  • looks like neural tissue
  • SON & PVN = located w/in blood brain barrier
    • make oxytocin & vasopressin
    • then transpored outside blood-brain barrier –> Herring bodies

Pituicytes

  • only in pars nervosa
  • like astrocytes (glial cells)
    • GFAP; Intermediate filament
      • glial fibrillary acidic protein
  • DO NOT SECRETE oxytocin or vasopressin

Herring bodies

  • end of axon filled w/ vesicles
  • STORE & SECRETE hormones
    • via neural stimulation

Note:

  • NB = neurosecretory bodies
  • P = pituicytes
  • C = capillaries
21
Q

What is this?

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A

Herring Body in Neurohypophysis

22
Q

What are the 2 Hormones from the Hypothalamus that are processed for secretion by the Posterior Pituitary?

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A
  1. Oxytocin
    • FUNCTION:
      • Stimulates contraction of mammary gland myoepithelial cells & uterine SM
    • synthesized as pre-proxyphysin
      • cleaved just after exocytosis:
        1. oxytocin
        2. neurophysin
          • stabilizes oxytocin
  2. Vasopressin
    • ​FUNCTION:
      • ​increases water permeabiity of renal collecting ducts
    • Synthesized as pre-pro-pressophysin
      • cleaved into:
        1. vasopressin
        2. neurophysin

NOTE:

  • BOTH hormones of the PARS NERVOSA
23
Q

What is this?

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A

Pineal Gland (aka Epiphysis Cerebri)

Basics:

  • dev from NEUROECTODERM in the posterior wall of 3rd ventricle
  • remains connected to brain via stalk
    • pine cone shaped
  • covered by PIA MATER
  • has BRAIN SAND
    • corpora arenacea
      • calcifed extracellular protein = radiologic landmark

Function:

  • transduces light into neuroendocrine secretion
    • melatonin = induces sleepiness
      • acts on hypothalamus + hypophysis
  • controls circadian rhythm

Cells:

  1. Pinealocytes
    • secrete melatonin at night
    • makes serotonin during the day
      • not secreted
    • basophilic cytoplasm w/ secretory vesicles
      • euchromatic nuclei
  2. Glial-like interstitial cells
    • like astrocytes
    • GFAP+
    • nuclei = dark & elongated
24
Q

What is this?

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A

Endocrine Pancreas – Islets of Langerhans

  • immunochemistry staining
25
What is this?
Brain Sand in the Pineal Gland
26
What is this?
**Islets of Langerhans** - Endocrine Pancreas **Types of cells:** 1. _Alpha cells_ * glucagon * release energy by glycogen & fat breakdown * increases blood glucose 2. _Beta cells = LOTS of these_ * Insulin * cause cells to uptake glucose * promotes decrease of blood glucose 3. _Delta cells_ * Gastrin * Somatostatin * inhibits release of other islet cell hormones (paracrine) * inhibits release of GH & TSH & HCL (parietal cells) 4. _F cells_ * Pancreatic polypeptide * stimulates chief cells * inhibits bile,pancreatic enzyme & bicard secretion * inhibits intestinal motility 5. _Epsilon cells_ * Ghrelin * increases appetite **Note:** * Best way to ID each cell is to use IMMUNOCYTOCEMISTRY
27
What is this?
**Cells of Parathyroid Gland** 1. _Chief cells_ * secrete PTH * arranged in a linear pattern around blood vessels * have more nucleus (basophilic) + less cytoplasm * function: * stimulates osteoclasts to resorb bone * increase serum Ca levels 2. _Oxyphils_ * dont secrete! * smaller nucleus, more cytoplasm (eosinophililc) * function: * none/inactive chief cells?
28
What is this?
**Cells of the Parathyroid Gland** **Basics of Parathyroid:** * 4 small glands on POSTERIOR thyroid * Cell in cords * 2 types: * Chief cells * Oxyphils **Structure of Parathyroid:** * Many blood vessels * CT capsule * Adipose tissue increases w/ age
29
What are the 3 major parts of the Anatomy of the Adrenal Gland?
1. **Cortex** 1. Origin = _MESODERM_ 2. cells in cords 3. wide capillaries 2. **Medulla** 1. Origin = _NEURAL CREST_ 2. cells in cords 3. wide capillaries 3. **CT capsule** * Trabeculae **Note:** * Located at superior poles of the kidney
30
31
What are the 5 Parts/Zones of the Adrenal Gland?
1. **Capsule** 2. **Zona Glomerulosa - CORTEX** * Aldosterone * Fxn: regulate salt balance 3. **Zona Fasiculata - widest part OF CORTEX (Spongiocytes)** * Cortisol (MORE) * Fxns: * Stimulate gluconeogenesis; * fat mobilization; * suppresses immune response * DHEA & androstenedione (LESS) 4. **Zona Reticularis - CORTEX** * Coritsol (LESS) * DHEA & androstenedione (MORE) * Fxn: Same as sex hormones 5. **Medulla** * Modified sympathetic post-ganglionic neurons * innervated by sympathetic preganglionic fibers (ACh) * Chromaffin cells * epinephrine (80%) * norepinephrine (20%) * Fxn: Vasoconstriction, increased bp, etc.
32
What is this?
Adrenal Gland Blood Supply: * Cortical arterioles * supply cortex + sinusoids * Medullary arterioles * form capillary network Source of Blood: * Medullary a.s. * Venous blood from cortical capillaries * drain thru adrenal v.
33
What is this?
Cells of the Adrenal Cortex
34
What is this?
Adrenal Cortex: Zona Glomerulosa and Fasiculata
35
What is this?
**Adrenal Cortical Cell ‐ TEM** **Steroid Secreting Cells:** * Abundant SER * Mitochondria w/ tubular cristae * Lipid droplets in cytoplasm _Protein Secreting Cells:_ * Abundant RER * Mitochondria w/ self-like cristae
36
What is this?
**Chromaffin Stain of Adrenal Gland** _Chromaffin cells_ * stain w/ chromium salts (dark purple) * **Function**: * modified sympathetic postganglionic neurons * lack axons * lack dendrites * _secrete_: * E * NE
37
What is this?
**Adrenal Medulla** _Chromaffin cells:_ * large * pale staining * have faint granules * w/ TEM = dense core granules
38
What is this?
**Thyroid Gland** **Basics:** * below cricoid cartilage * 2 lobes connected by isthmus in ventral neck * CT capsule that makes septae (CT going into gland) **Blood supply:** * inferior thyroid a. * inferior thyroid v. **Cell Types:** * Follicular cells * Parafollicular aka C cells
39
What is this?
**Thyroid Gland** **Follicular Cells (Thyrocytes)** * _Structure:_ * simple squamous --\> columnar * active = low columnar * hypoactive = squamous * _Function:_ * form follicles * _secrete thyroglobulin to center of follicle (colloid)_ * **_make T3 & T4_ --\> growth/differentiation/basal metabolic rate** * only gland that STORES its hormone EXTRACELLULARLY * _Origin:_ * _ENDODERM lining of foregut_ * grows inferiorly out of epithelial diverticulum * connection to pharynx (thyroglossal duct) regresses **Parafollicular cells:** * _Structure:_ * larger & lighter stain than follicular cells * do NOT touch colloid * w/in BL * _Function:_ * **_secrete calcitonin_ --\> osteoblasts = tone bone** * **​**PTH = antagonist * _Origin:_ * _​NEURAL CREST CELLS_ **Notes:** * Thyroid hormones * iodide oxitation * digestion of thyrogloblin by lysosomal enzymes * release T3 & T4 in cells * secreted from BL & uptaken by blood vessels
40
What is this?
**Thyroid Gland** **Follicular Cells (Thyrocytes)** * Function: * secrete thyroglobulin to center of follicle (colloid) * **make T3 & T4 --\> growth/differentiation/basal metabolic rate** * only gland that STORES its hormone EXTRACELLULARLY * Origin: * ENDODERM lining of foregut * grows inferiorly out of epithelial diverticulum * connection to pharynx (thyroglossal duct) regresses **Parafollicular cells (C cells)** * Function: * **secrete calcitonin --\> osteoblasts = tone bone** * ​PTH = antagonist * Origin: * ​NEURAL CREST CELLS
41
What is this?
TEMs of Thyroid Gland Cells

HSF Block 3 (7 decks)

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