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COT - Exam 2 > 14.2 Lab + Lecture Notes > Flashcards

14.2 Lab + Lecture Notes Flashcards

1
Q

Endocrine Cell

A
  • secretes a product basal (i.e into surrounding CT)
  • can occur singly (e.g. tracheal/GI epithelia)
  • can be a shared FXN of another cell type
  • generally have prominent basal surface
  • surrounded by dense + extensive capillary network
  • usually (1 exception - follicular cells of thyroid) lack a lumenal (apical) surface
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2
Q

Parathyroid

A
  • most numerous cell = chief cell (sometime called principal cell)
  • Oxyphil cell = minority cell type - increase in number with aging - so frequency is not the best way to recognize the cells
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3
Q

Thyroid

A

= source of hormones T3 + T4 (both incorporate iodine in structure)

  • secondary funciton = sequestering + storage of iodine
  • contain follicular cells = endocrine cells with an apical surface that functions in storing the iodine
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4
Q

Follicular cells

A

= endocrine cells with an apical surface (is rare occurrence)

  • apical lumen forms a sealed compartemtn with iodine stored bound to thryoglobulin
  • connect with each other via tight junctions - that create an apical and basal polarity to the cells
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5
Q

Thyroglobulin

A
  • prominent eosinophilic material
  • fills the lumen of thyroid follicle
  • better to be called colloid
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6
Q

2 types of endocrine cells in thyroid

A

1) parafollicular cell = less frequent of the two
- called the C-cell
- produces calcitonin
2) ? follicular cell

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7
Q

Pituitary

A

= endocrine organ sitting at base of brain

  • surrounded + protected by Sella turcica (indention in base of skull)
  • derived from apposition of 2 embryonic tissues
    1) Oral ectoderm –> adenohypophysis
    2) Neural ectoderm –> neurohypophysis
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8
Q

Sella Turcica

A

= indentation in base of skull

- surrounds + protects the pituitary gland

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9
Q

Neurohypophysis

A
  • axons of neurons seen here whose cells bodies sit in hypothalamus
  • 2 products secreted by the axons are:
    1) ADH
    2) Oxytocin
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10
Q

Adenohypophysis

A

= collection of basal secreting cells surrounded by extensive capillary network

  • 3 morphologically distinguishable parts
    1) Pars distalis - comprises bulk of structure
    2) Pars intermedia - lies immediately adjacent to neurohypophysis
    3) Pars tuberalis - surrounding stalk of pituitary (which is itself part of neurohypophysis)
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11
Q

Classification of cells of adenohypophyssi

A

1) Acidophils
2) basophils
- hormones produced by basophils have glycogen precursors (will stain well in PAS stains)
3) Chromophobes

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12
Q

Pineal Gland

A
  • sits in center of brain
    = glandular tissue clustered in cords
    = surround by CT that is an extension of pail tissue of brain
  • principle product = melatonin (inhibited by light and regulates circadian rhythms)
  • has abundant capillaries
  • morphologically distinguishable due to corpora arenacea
  • parenchyma cell = pinealocyte
  • has stromal glia cells too
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13
Q

Corpora arenacea

A

= brain sand
= unique metabolic byproduct
- accumulated throughout life as microscopic calcified particles

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14
Q

Pinealocyte

A

= parenchymal cell of pineal gland

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15
Q

Adrenal Gland

A
  • unique because is endocrine organ with a layered organization
  • sits above kidney (suprarenal gland)
  • surrounded by capsule of CT
  • outermost portion = adrenal cortex
  • inner portion = adrenal medulla
  • the 2 parts are from separate embryonic sources
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16
Q

Blood Supply/Flow in Adrenal Gland

A
  • 3 suprarenal arteries - supply blood to gland
  • 1 suprarenal vein - carries blood away
  • blood flows from periphery to center
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17
Q

3 layers of adrenal cortex

A
  • all layers produce steroid hormones –> called corticosteroids
  • layers from outside in:
    1) zona glomerulosa
    2) zone fasiculata
  • cells have canonical appearance of steroid producing cells
  • -> frothy/bubbly cytoplasm due to intracellular cholesterol
    3) Zona reticularis
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18
Q

The amount of cholesterol in each layer of cortex depends on..

A

1) Whether enzyme that cleaves cholesterol (SCC) is rate-limiting step
2) Local availability of cholesterol carrier proteins (StAR)

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19
Q

Medullary Arteries

A

= long cortical arteries

= arteries that traverse the cortex

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20
Q

Adrenal Medulla

A
  • 2 major products

- chromatin cells (named for high affinity for chromium salt dyes)

21
Q

Pancreas

A
  • majority of it = exocrine gland that empires products into common bile duct
  • islets of langerhans = islands of endocrine tissue in the exocrine tissue
  • 4 types of intermixed cells (can be differentiated via antibody stains)
  • products = glucagon, insulin, SST, PP
  • products do not stain well in H&E compared to exocrine zymogen granules
  • pancreas has unique circulation
22
Q

Unique circulation of Pancreas

A
  • Blood enters islets via arterioles
  • leaves via capillaries that then enter exocrine tissue
  • exocrine pancreas sees concentrations of islet-produced hormones at higher concentrations than generally found in circulation
23
Q

Define a “hormone” through describing the possible types of secretions

A
  • Autocrine secretion - affects the producing cells
  • paracine secretion - affects the neighboring cells
  • neurocrine secretion - secretion from a neuron to a cell (specialized type of paracrine)
  • “true” endocrine - affects distant cells
24
Q

Describe the relevant general morphologic features of endocrine cells/organs/tissues

A
  • fenestrated capillaries
  • surrounded by close + extensive capillary (fenestrated) network
  • cells lack polarity - more specifically most lack of true “apical” surface
  • have prominent basal surfaces usually due to secretions
25
Q

What are the two types of hormones (per the slides) and their characteristics

A

1) Protein hormones (amino/peptide)
- usually extracellular receptors, not lipid soluble, often soluble in aqueous environments and do not require carriers
2) Steroid Hormones
- mostly constitutive secretion - regulated by how fast secreted
- often have carrier proteins, and/or binding proteins
- lipid soluble
- intracellular receptors

26
Q

Three types of hormone receptors

A
  • cell membrane
  • intracellular
  • nuclear membrane
27
Q

Control of hormones

A
  • via releasing factors –> positive feedback

- via inhibiting factors –> negative feedback

28
Q

What are the two relevant nuclei in the hypothalamus discussed in lecture

A
  • PVN (paraventricular nuclei)

- SON (supraoptic nuclei)

29
Q

Describe the components of the Pituitary Neurohypophysis

A

= posterior pituitary

  • Neuropil = descending axons from hypothalamic neurons form PVN, SON
  • Capillaries = sinusoidal by anatomical size (walls are fenestrated)
  • Pituicytes = resident glial cells - control the blood/brain barrier
  • Herring Bodies = dilated endings of axons, containing hormones for release into circulation
30
Q

What are the hormones secreted from neurohypophysis

A

1) ADH
- targets kidney collecting ducts
- FXN: water retention
2) Oxytocin
- FXN: milk “let-down”

31
Q

What is the unique pituitary circulation and where have we seen it before

A

= Venous portal system

  • has two capillary beds connected by a vein
  • 1st time we saw this was in liver portal system
32
Q

Define the different anatomical features of the two parts of the pituitary gland

A 
1) Neurohypophysis = Posterior Pituitary - 3 parts
A) Pars Nervosa
B) Infundibular Stalk
C) Median Eminence
2) Adenohypophysis
A) Pas Distalis
B) Pars Intermedia
C) Pars tuberalis
33
Q

Describe the pituitary embryology and give a brief overview of the steps of development

A
  • Two parts of pituitary are formed from 2 separate tissues
    A) Neural ectoderm forms the neurohypophysis
    B) Oral Ectoderm forms the adenohypophysis
  • Steps in development
    1) Beginning formation of Rathke’s pouch from oral ectoderm and infundibular process from neural ectoderm
    2) Neck of Rathke’s Pouch gets constrained by growth of mesoderm
    3) Rathke’s pouch pinches off
    4) Pinched off segment conforms to neural process - forming pars distalis, pars intermedia, pars tuberalis
    5) Pars tuberalis encircles infundibular stalk (settles into mature conformation)
34
Q

What are the 5(7) hormones produced from the adenohypophysis, their corresponding staining and function

A

1) Growth Hormone: GH, SST
- Acidophil
- FXN: growth
2) Prolactin (PRL)
- acidophil
- FXN: milk secretion
3) Adrenocorticotropin (ACTH)
- Basophil
- FXN: Adrenal Cortex Hormone
4) Gonadotropins: FSH + LH
- Basophil
- FXN: stimulates germ cell development
5) Thyroid Stimulation hormone (TSH)
- Basophil
- FXN: thyroid hormone

35
Q

Describe the 5 layers (outside–>in) of the adrenal gland and relevant hormone types produced from each

A

1) Capsule
2) Cortex: Zona Glomerulosa
- secretes mineralcorticoids
3) Cortex: Zona Fasiculata
- secretes glucocorticoids
4) Cortex: Zona reticularis
- secretes gonadocorticoids
5) Adrenal Medulla
- secretes NE + Epi

36
Q

Describe the embryologic origin of the adrenal gland

A
  • Cortex and medullar are from 2 separate embryologic origins
  • Neural crest cells - develop into chromatin cells + migrate into developing cortex and invade center to give rise to the medulla
  • Cortex comes from the intermediate mesoderm?
37
Q

Discuss the blood supply/flow of blood of the adrenal gland

A
  • 2 routes for blood to travel in adrenal gland
    1) Capsular artery –> cortical arteriole –> capillary bed through the cortex via adrenocortical sinusoid –> adrenomedullary collecting vein (in zona reticularis) –> Medullary capillary –> central adrenomedullary vein
    2) Traverse cortex via medullary arteriole (from capsular artery) –> medullary capillary –> central adrenomedullary vein
  • pathway #2 allows a decreases the collection of cortical compounds on the way to medulla = effective way to supply/get to just the medulla
38
Q

What are the major hormone products of each part of the adrenal cortex, what type of corticosteroid they are, and their function

A

1) Aldosterone (mineralocorticoid)
- from zona glomerulosa
- FXN: blood pressure/ sodium absorption
2) Cortisol (glucocorticoid)
- from zona fasciculata
- FXN: Fat/Carb/Protein mobilization; ACTH influence
3) Dihydroepiandrostenidone (DHEA) (androgens)
- from zona reticularis
- FXN: secondary sex characteristics

39
Q

What are the major hormone products of each part of the adrenal medulla, and what cell is responsible for them

A

= Chromaffin cells

- Secrete epinephrine (adrenaline) + NE (noreadrenaline)

40
Q

What are the hormone products of the thyroid gland, what cells do they come from, and what is their function

A

1) T3 (triodothyronine) + T4 (thyroxine)
- from the follicular cells
- FXN: Protein syntehsis/degradation, glycogenesis, lipolysis, HR, General growth + metabolism
2) Calcitonin
- from C-cells (parafollicular cells)
- FXN: lowers blood calcium

41
Q

Describe thyroid embryology

A
  • developed early in embryonic life from the foregut endoderm
  • near the base of developing tongue
  • (parathyroids from pharyngeal pouches)
42
Q

Describe the thyroid production of T3 and T4

A
  • Thyroglobulin is made from follicular cells and secreted into colloid
  • In colloid it forms MIT (monoiodinated thyroglobulin) + DIT (diiodinated thyroglobulin) = the storage form of bound iodine
  • these molecules are endocytosed and exposed to lysosomes to release the iodine to be used for T3/T4 synthesis (colloid components recycled)
43
Q

Describe the ultrastructure + shape of follicular cells

A
  • Shape of follicular cells is highly dependent on their level of activity
  • can range from columnar to cuboidal

Ultrastructure includes:

  • Rich basal rER
  • connected via tight junctions
  • nucleus is round + central
  • apically have golgi complexes, secretory granules, phagosomes/lysosomes, microvilli
44
Q

What are two thyroid pathologies

A
  • Goiter = from iodine deficiency (increases TSH production)

- Grave’s Disease = chronic stimulation and release of thyroid hormones

45
Q

Describe the Hormones released from the parathyroid glands, the cells that release them and their functions

A

1) Parathormone (PTH)
- PTH Principal cells (chief cells) = 95% of the cells
- FXN: calcium regulation (antagonist of calcitonin)
- darkish staining cells
2) Oxyphil cells
- unknown hormone or function
- 5% of the cells
- light staining cells

46
Q

Describe the hormone produced by the pineal gland and other components of the gland

A
  • Hormone = melatonin
  • Hormone producing cell = pinealocytes - may contain lipofuscin - FXN: in circadian rhythms
  • also have glial cells here
  • Brain Sand (Corpora arencea) = calcified metabolic product + identifier of pineal gland in histology
47
Q

Describe the hormones produced by the pancreatic islets (in the order they are developed), the cells that produce them, and their function

A

1) Glucagon
- produced by alpha cells
- FXN: raises blood glucose
2) Insulin
- produced by beta cells
- FXN: lowers blood glucose
3) SST
- produced by delta (D) cells
- FXN: inhibits pancreatic secretions
4) Pancreatic polypeptide (PP) & Vasoactive intestinal peptide (VIP)
- produced by PP (D)
5) Ghrelin
- produced by E cells
- FXN: appetite regulation

48
Q

What is the Diffuse Neuroendocrine System (DNES)

A
  • Neuroendocrine compounds (cells) in the GI and respiratory system
  • below is a partial list of examples in GI followd by their secreting cell in parenthesis (not to be memorized
  • Stomach: Gastrin (G) + SST (D)
  • Duodenum/Jejunum: Secretin (S) + CCK (I) + Glucose-dependent (K) + SST (D) + Motilin (M)
  • ileum/colon: enteroglucagon (L) + Peptide YY [abbrev. PYY] (L) + Neurotensin (N) + SST (D)

COT - Exam 2 (28 decks)

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