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Endo/Repro > Histology of the Endocrine Organs > Flashcards

Histology of the Endocrine Organs Flashcards

1
Q

The exocrine pancreas is a compound tubuloalveolar serous gland that synthesizes and secretes digestive enzymes into the duodenum. What volume of the pancreas is this component?

A

98%

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2
Q

The pancreas has a head, neck, body, tail and capsule. Describe the structural components of the capsule. What are its contents? Is it stricty speaking a “capsule”?

A

»Loose connective tissue covers surface and extends deep into gland as septa, dividing organ into lobules
»Contains blood vessels, lymphatics, nerves and excretory ducts
»Not a capsule proper (would be dense CT with lots of collagen)

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3
Q

The acinus is the functional/secretory unit. Describe the shape and contents of acinar cells.

A

•Pyramidal serous cells
–Have narrow luminal surface and broad basal surface
–Water secretion
•Basophilic basal cytoplasm
•Acidophilic granules
–In apical cytoplasm, contain zymogens
•Basal nucleus with extensive rER and Golgi
•Apical tight junctions and microvilli

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4
Q

Intercalated ducts lead from the acinus, what cells are found here? Describe them.

A

–Centroacinar cells
•Squamous, weakly staining and agranular

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5
Q

What is the duct that drains the intercalated ducts into the main pancreatic duct, that is made of columnar epithelium?

A

Interlobar ducts

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6
Q

What are the functional/secretory units of the endocrine pancreas?

A

Islets of Langerhans

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7
Q

Islets of Langerhans appear as islands but are actually anastamosing irregular cords that vary in size from a few to hundreds of cells. Describe the cell shape, surroundings and staining.

A

–Cluster of weakly staining, polygonal cells surrounded by dark staining acini
»Fenestrated capillaries abundant

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8
Q

What do the arrows indicate?

A

Islets of Langerhans

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9
Q

What do the arrows indicate?

A

Alpha cells

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10
Q

What percent of the islets are alpha cells? Where are they located? What do they secrete?

A

–15-20% of islet
–Located at the periphery
–Glucagon secreting

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11
Q

What percent of islets are Beta cells? Where are they found in the islet? What do they secrete (primarily)?

A

–70%
–Core of islet
–Insulin secreting

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12
Q

What percent of the islet is comprised of delta cells? Where are they located in the islet? What do they primarily secrete?

A

–5-10%
–Located at the periphery
–Somatostatin secreting

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13
Q

What is the hypothalamohypophysial System comprised of?

A

–Endocrine and neuroendocrine components

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14
Q

Roughly what size is the hypophysis? What is another name for this? What kind of gland is it?

A

•Pituitary (Hypophysis)
–Pea sized
–Compound endocrine/neuroendocrine gland

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15
Q

Describe where the pituitary gland can be found.

A

•Located at the center of the base of the brain in a depression of the sphenoid bone called the sella turcica

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16
Q

What is the adenohypophysis made of? What are the three parts of it?

A

–Anterior lobe made of glandular epithelium

  1. Pars distalis
  2. pars intermedia
  3. pars tuberalis
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17
Q

What makes up the bulk of the anterior lobe of the adenohypophysis?

A

Pars Distalis

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18
Q

This abuts the pars distalis, and is sometimes referred to as the intermediate lobe. What is it?

A

Pars intermedia

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19
Q

What does the pars tuberalis form?

A

A sheath around the infundibulum

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20
Q

What is the neurohypophysis made of? What are its two parts?

A

–Posterior lobe made of neural secretory tissue

  1. Pars Nervosa
  2. Infundibulum
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21
Q

What is found in the pars nervosa?

A

•Neurosecretory axons and their endings

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22
Q

The infundibulum is a stalk existing between the pituitary and the hypothalamus. What does this give rise to? What does this contain, and what do the contents give rise to?

A
  • Stalk existing between the pituitary and the hypothalamus
  • Gives rise to the median eminence
  • Contains the neurosecretory axons forming the hypothalamhypophyseal tracts
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23
Q

What are the components of the Hypothalamohypophyseal portal system?

A
  • Superior hypophyseal arteries
  • Hypophyseal portal veins
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24
Q

What do the superior hypophyseal arteries supply? What do they give rise to?

A

Supply superior structures including:

  • Median eminence
  • Infundibulum
  • Pars tuberalis

–Give rise to primary capillary plexus
•Fenestrated capillaries

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25
Q

Where are the hypophyseal portal veins located? What do they drain? Where do they drain to?

A

–Located in pars tuberalis
–Drain primary capillary plexus
–Into secondary capillary plexus
•In pars distalis

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26
Q

The hypothalamohypophyseal portal systemcarries neuroendocrine secretions of hypothalamic nerves from their sites of release in the_____________ and _____________to the cells of the pars distalis

A

median eminence

infundibulum

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27
Q

Where do the neurons of the Hypothalamohypophyseal tracts end?

What do they do?

A

•Neurons end in close proximity to the fenestrated capillary networks
–Of the infundibulum/ pars tuberalis
–Of the pars nervosa

•Store and release secretory vesicles

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28
Q

What is the structure of the adenohypophysis?

A

•Typical endocrine structure
–Fenestrated sinusoidal capillaries
–Cords of cells

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29
Q

What hormones are produced in the adenohypophysis?

A

•Site of tropic hormone production
–Adrenocorticotropic hormone (ACTH)
–Thyroid stimulating hormone (TSH)
–Follicle-stimulating hormone (FSH)
–Luteinizing Hormone (LH)
•Site of growth hormone (GH) production
•Site of prolactin (PRL) production

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30
Q

What type of cells are found in the pars distalis?

A

–Parenchymal cells (functional cells as opposed to structural cells, i.e. stromal)

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31
Q

The pars distalis has two different staining classes, what are they?

A

Chromophils

Chromophobes

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32
Q

Chromophils readily take up stain, what types of these cells are found in the pars distalis?

How do they stain?

Where are they located?

A

–Acidophils
»Stain pink with H&E
»Primarily found in the center

–Basophils
»Stain darker with H&E
»Primarily found in the periphery

33
Q

What cell type might chromophobes be?

A

»Could be acidophils and basophils that have released their granules

34
Q

What are the protein hormone synthesizing cells of the pars distalis?

A
  1. Somatotropes
  2. lactotropes
  3. corticotropes
  4. gonadotropes
  5. Thyrotropes
    6.
35
Q

What are the pars distalis acidophils? What do each produce?

A

–Somatotropes
•GH containing

–Lactotropes
•PRL containing

36
Q

What are the basophils of the pars distalis? What do they contain?

A

–Corticotropes
•ACTH containing

–Gonadotropes
•FSH and LH containing

–Thyrotropes
•TSH containing

37
Q

What is the pars tuberalis and extension of?

A

The pars distalis

38
Q

The function of the pars intermedia is unclear, what is it the embryologic remnant of?

A

Rathke’s pouch

39
Q

Describe the histological features of the pars intermedia

A

•Colloid filled cavities
•Basophils
–Likely coricotrophs
–Stain deep blue
•Chromophobes

40
Q

The neurohypophysis is located posteriorly, lighter stainind than the adenohypophysis and has a neuroendocrine structure. What is this the site of release of? Where are these things synthesized?

A

•Site of release of oxytocin and ADH
–Primarily synthesized in the cell bodies in hypothalamus

41
Q

The pars nervosa is a component of the neurohypophysis, what tissue type does it resemble? What type of axons are present and what do they contain?

A

•Resembles nervous tissue
•Non-myelinated axons
–Containing neurosecretory vesicles
»Herring bodies
•Distended terminations of axons where they contact capillaries

42
Q

What are the specialized glial cells of the pars nervosa?

A

Pituicytes

43
Q

What is the master neuroendocrine gland and major controlling center of the autonomic nervous system?

A

Hypothalamus

44
Q

What are the major neurosecretory functions of the hypothalamus?

A
  1. Oxytocin
  2. ADH (vasopressin)
  3. Hypothalamic regulating hormones
45
Q

How are oxytocin and ADH released?

A

•Released into circulation in the pars nervosa of the posterior pituitary

46
Q

How are the hypothalamic regulating hormones released?

A

•Released into portal system in the median eminence/ infundibulum

47
Q

What do hypothalamic regulating hormones do? What are they?

A

Promote or inhibit the secretion of hormones from pars distalis of the anterior pituitary
•Growth-hormone releasing hormone (GHRH)
•Somatostatin
•Dopamine
•Corticotropin-releasing hormone (CRH)
•Gonadotropin-releasing hormone (GnRH)
•Thyrotropin-releasing hormone (TRH)

48
Q

Describe the shape, location and secretions of the pineal gland.

A

–Spherical 6-10 mm
–Midline of brain just below corpus callosum
–Melatonin secreting

49
Q

What are the cell types of the pineal gland?

A

Pinealocytes

Neuroglia

corpora arenacea

50
Q

Neuroglia resemble astrocytes, where are they found in the pineal gland?

A

–Surrounding pinealocytes and capillaries

51
Q

Pinealocytes are highly modified neurons that poisess a secretory function. How are they arranged? Where do their branched processes terminate?

A

–Arranged in clusters and cords around fenestrated capillaries
–Branched processes terminate on capillaries

52
Q

Corpora arenacea is described as “brain sand”, what is this stuff? What is it useful for?

A

–Calcium phosphate crystal deposits secreted by pinealocytes
–Has no known effect on function
–Becomes evident in 20s and is important radiography biomarker for midline of brain

53
Q

The thyroid is a bilobate endocrine gland. What is it connected by? It is invested by connective tissue that dive deep to form what?

A

Connected by isthmus

form trabeculae

54
Q

Where is the thyroid located?

A

Anterior neck, adjacent to larynx and trachea

55
Q

What is the functional unit of the thyroid? What is its shape?

A

Thyroid follice, roughly spherical, cyst-like

56
Q

The follicular epithelium invests follicles and is comprised of what two types of cuboidal cells?

A

Follicular cells

Parafollicular cells

57
Q

What are follicular cells responsible for?

A

»Responsible for the production of thyroid hormone
(both secretory and absorptive functions)

58
Q

Describe the appearance of active vs. inactive follicular cells

A
  • Inactive- simple, flat, cuboidal
  • Active- taller, more cytoplasm, paler nucleus
59
Q

Are these follicular cells active?

A

No

60
Q

Are these follicular cells active?

A

Yes

61
Q

Where are parafollicular cells located?

A

–Located in follicle basal lamina
•In periphery, no exposure to colloid

62
Q

What do parafollicular cells (C cells) secrete?

A

Calcitonin

63
Q

How many glands is the parathyroid composed of?

A

–Two pairs of endocrine glands (4 total)
•Superior and Inferior

64
Q

What are the two cell types of the parathyroid gland?

A

Principle (chief) cells

Oxyphil Cells

65
Q

Principle (chief) cells of the parathyroid are more numerous, what do they synthesize?

A

PTH

66
Q

Adipose tissue is found in the parathyroid, and increases with age ultimately consuming up to what percent of its mass?

A

70%

67
Q

What are the two parts of the adrenal glands? What does each secrete?

A

•Cortex
–Steroid secreting portion (90% of weight)

•Medulla
–Catecholamine-secreting portion
»Epinephrine and norepinephrine

68
Q

What are the three zones of the adrenal cortex?

A
  • Zona glomerulosa (G)
  • Zona fasciculata (F)
  • Zona reticularis (R)
69
Q

What are the cells of the adrenal medulla? What do they contain?

A

Chromaffin cells

Myelinated nerve fibers, under control of SNS

70
Q

The zonula glomerulosa is the outermost 15% of the cortical volume and appears thin due to the outer location. What do the cells secrete? What does this control? What system regulates this?

A

•Mineralocorticoid secreting
–Electrolyte and fluid homeostasis
–Under control of the renin-angiotensin aldosterone system

71
Q

What does the zona fasciculata secrete? What does this influence? What controls this?

A

•Glucocorticoid secreting
–Influences metabolism of carbs, proteins and lipids
–Under the influence of ACTH

72
Q

What secretions are produced by cells of the zona reticularis?

A

•Both glucocorticoid and androgen secreting cells present

73
Q

•A 45 y/o male presents to a PCP complaining of intense, recurrent headaches and visual field defects persisting, and increasing in intensity, over the past 5 years. Physical examination reveals normal blood parameters, course facial features, prominent supraorbital ridge, enlarged fleshy nose and protruding jaw and lips. The patient reports the appearance of multiple skin tags and an inability to wear his wedding ring in the last 12 months. A T1-weighted MRI is ordered to identify the source of complaints. Which of the following do you believe to be involved?

A.Pineal gland
B.Adrenal cortex
C.Adrenal medulla
D.Anterior pituitary
E.Posterior pituitary

A
74
Q

1/3 of anterior pituitary adenomas are clinically non functioning. What are the symptoms related to in these cases?

A

–Symptoms related to compression of nearby structures
•Headaches
•Visual field defects
•Prolactin secretion from stalk compression

75
Q

•After surgical removal of the anterior pituitary adenoma, a histochemical analysis is ordered, which includes immunoreactivity for GH. The images indicate which specific cell type is involved?
A.Chromophobes
B.Somatotropes
C.Acidophils
D.Basophils
E.Oxyphil cells

A
76
Q

GH-secreting pituitary adenomas are 20% of pituitary adenomas. What are two primary presentations of this?

A

Acromegaly

Gigantism

77
Q

When is acromegaly typically seen? How does it progress?

A
  • Mean diagnosis at 40-45, men and women affected
  • Slowly progressing symptoms, 10 year delay of diagnosis
78
Q

When is gigantism seen?

A
  • In children and adolescents before epiphyseal plate closure
  • Extremely rare
79
Q

A diffusely enlarged thyroid is associated with Graves disease. The image below, taken from a patient with Graves disease, indicates what?

A.Hyperplasia of the follicular epithelium
B.Hypoplasia of the follicular epithelium
C.Hypertrophy of the follicular epithelium
D.Hyperplasia of parafollicular cells
E.Hypertrophy of parafollicular cells

A

Endo/Repro (19 decks)

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