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Histology > Endocrine System > Flashcards

Endocrine System Flashcards

1
Q

What does the endocrine system produce?

A

various secretions:
- hormones
- hormonally active substances

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2
Q

Where do hormones and hormonally active substances go?

A
  • enter the circulatory system
  • transport to target cells
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3
Q

What classes are hormones and hormonally active substances divided into?

A

Peptides:
- insulin
- GH
- ACTH

Steroids:
- gonadal
- adrenocortical steroids

Amino Acids / Arachidonic Acid Analogs:
- catecholamines
- prostaglandins

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4
Q

What is the function of the endocrine system?

A
  • coordinates cell activities (organelles and tissues)
  • maintains homeostasis
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5
Q

What are endocrine glands?

A

Glands whose major function is to secrete hormones.

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6
Q

State the endocrine part of the pancreas.

A

endocrine
exocrine- digestion (duct –> enzyme secretion)

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7
Q

What is the difference between endocrine and exocrine glands?

A

endocrine glands: no ducts! (secrete is always hormones!) released into circulatory system!
exocrine glands: has a duct system!

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8
Q

What is a different name used to describe the pituitary gland?

A

hypophysis

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9
Q

What two parts is the pituitary gland composed of?

A

1) Anterior Lobe (adenohypophysis):
- glandular epithelial tissues consisting of 3 parts: pars distalis, intermedia and tuberalis.

2) Posterior Lobe (neurohypophysis):
- neural secretory tissue
- developed from the neuroectoderm of the CNS

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10
Q

What is the anterior lobe of the pituitary gland made up of? Other name?

A

anterior lobe = adenohypophysis
GLANDULAR EPITHELIAL TISSUES
- pars distalis
- pars intermedia
- pars tuberalis

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11
Q

What is the posterior lobe of the pituitary gland made up of? Other name?

A

posterior lobe = neurohypophysis
NEURAL SECRETORY TISSUE
- developed from the neuroectoderm of the CNS

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12
Q

State the overall key points about the pituitary gland.

A
  • small gland
  • attached to the inferior surface of the brain
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13
Q

What similarities do the two pituitary lobes share?

A

rich capillary network (necessary for picking up secreting hormones)

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14
Q

Which part of the anterior lobe glandular epithelial cells is most histologically important? Why?

A

pars distalis: produces most hormones

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15
Q

State the histological composition of the pituitary gland.

A
  • connective tissue stroma (supporting parenchymal cells) (between secretory cells)
  • secretory cells
  • secretory granules in pars distalis are identified as basophils (10%), acidophils (40%) and chromophobes (50%)
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16
Q

How are cells in the pars distalis of the pituitary gland identified? Into what?

A
  • based on staining reactions

endocrine cell secretory granules:
- basophils (10%), (blue - hematoxylin)
- acidophils (40%) (dark red - eosin dye)
- chromophobes (50%) (orange/clear - (dye)phobia)

impossible to depict which cell produces which hormone!

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17
Q

What makes up most of the posterior lobe of the pituitary gland? Other name?

A

Pituitary gland = hypophysis
- extention of the CNS

Axons (projecting from the neuron cell bodies in the supraoptic and paraventricular nuclei of the hypothalamus) make up most of the posterior lobe.

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18
Q

What is the function of the pituitary gland?

A

releases hormones

produced in the supraoptic nuclei of the hypothalamus:
- antidiuretichormone [ADH]
- vasopressin

paraventricular nuclei of the hypothalamus:
- oxytocin

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19
Q

Where are hormones produced for the pituitary gland?

A

in the hypothalAmus

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20
Q

What is the greatest difference between the anterior and posterior lobes of the hypophysis?

A

anterior lobe: produces hormones (secratory epithelial cells);
posterior lobe: stores hormones and releases them at specific times.

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21
Q

What is another name used for the Epiphysis Cerebri?

A

pinneal gland

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22
Q

What is the epiphysis surrounded by?

A

pia mater capsule

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23
Q

State the composition of the epiphysis cerebri.

A

Pinealocytes:
- primary cells
- large
- basophilic cells
- round nuclei
- secrete melatonin (association with circadian rhythms)

Astrocytes:
- interdigitate between the pinealocytes and capillaries
- astocyte like neuroglial cells (metabolism associated)

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24
Q

What is the stroma of the epiphysis cerebri based on?

A

pia mater

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25
Q

What is a special structural component found in the epiphysis cerebri? What is its function? What is it composed of?

A

Corpora Arenacea:
- intercellular calcium deposits
- associated with aging (accumulate with age)
- do not seem to affect glandular function.

  • light-sensitive endocrine organ is
    responsible for the production of
    melatonin and serotonin.
  • histological importance: helps indicate the specific location of the epiphysis cerebri

known as “brain sand”

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26
Q

What is the thyroid gland surrounded by?

A

connective tissue capsule:
- fine septa between the
follicles

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27
Q

State the arrangement of the parenchyma of the thyroid gland.

A
  • spherical follicles
  • surrounded by a dense capillary
    network
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28
Q

State the histological composition of the thyroid gland.

A

(1) surrounded by a connective tissue capsule (fine septa b/w follicles).

(2) parenchyma arranged in spherical follicles (size varies with activity)
- size of follicles varies with
activity
- epithelium of follicles consists of
follicular lining cells ** (squamous - columnar)
- acidophilic lining with
numerous cytoplasmic secretory
vesicles, a basal nucleus and microvilli (apical surface).

(3)surrounded by a dense capillary
network.

squamous- no hormone production

columnar- hormone producting

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29
Q

What is a specific feature of the thyroid gland?

A

Usually glands are made up of a homogenous mass, yet the thyroid gland has follicles (spherical structure compartments).

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30
Q

What is the function of follicular cells? Where does this process take place?

A

produce thyroid hormones T4 and T3.
synthesis takes place in:
- follicular cells
- lumen of the follicle.

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31
Q

What is the function of parafollicular cells?

A

produce calcitonin (calcium level regulation).

32
Q

State the composition of the follicle lumen.

A

Lumen is filled with a gellike mass called colloid, which contains
thyroglobulin, an inactive storage form of thyroid hormones.

33
Q

State the location of the parafollicular cells. How can they be depicted? Other name?

A

Parafollicular cells = C cells

Location:
- outside the follicular lining epithelium
- do not extend to the lumen of the
follicle.

Depiction:
- lighter staining
- larger
- oval in shape

34
Q

What is an additional structure surrounding all glands?

A

rich network of blood vessels!

35
Q

What are the two cells present in the thyroid gland?

A
  • follicular cells (in the follicle)
  • parafollicular cells (near follicles)
36
Q

State the location of the parathyroid gland. Birds?

A

External parathyroid glands:
- cranial pole of the thyroid
- ABSENT in birds and pigs

Internal parathyroid glands:
- caudal pole
- (embedded within the thyroid tissue)

37
Q

What surrounds the parathyroid gland? What does it blend with?

A

thin connective tissue capsule
- blends with the thyroid connective tissue

thin connective tissue = stroma

38
Q

What extends from the capsule of the parathyroid gland into the parenchyma? What does it contain?

A

Fine septa extend from the capsule into
the parenchyma and contain the rich
endocrine blood supply.

39
Q

Is it possible to depics two glands in one histological slide?

A

yes! the thyroid and parathyroid gland!

40
Q

What is the parenchymal part of the parathyroid gland composed of?

A

Principal cells = Chief Cells:
- polygonal cells
- round nucleus
- clear cytoplasm
- actively produce parathyroid
hormone (PTH) (increases
blood calcium levels).

Oxyphil cells:
- inactive (function is unknown)
- larger
- more intensive colour (pink)
- prominent cell membranes
- cytoplasm contains glycogen or lipofuscin.

41
Q

What is the function of the parathyroid hormone?

A

Parathyroid Hormone (PTH):
- increases blood calcium levels
- increases mobilization of calcium from bone
- increases calcium absorption in the intestines,
- reduces calcium loss in the urine

42
Q

State the positioning of the two cells of the parathyroid gland.

A

no specific location!
chief cells and oxyphil cells are mixed together.

43
Q

What are suprarenal glands? Where are they located? What do they represent?

A

Suprarenal Glands = Adrenal Glands
- adjacent to the cranial medial border
of the kidneys
- represent two distinct endocrine tissues.

44
Q

State the major functions of the suprarenal glands. How is it regulated?

A

Outer cortex secretes steroid hormones.

Medulla produces catecholamines.

  • Hormone production is regulated
    independently    .
45
Q

What is the suprarenal gland surrounded with? How does this connect with the parenchyma? What is its function?

A

surrounded by: dense fibrous connective tissue capsule.

  • Connective tissue trabecula extend into the parenchyma from the capsule and a fine
    stroma     supports the glandular cells.
46
Q

Why is the name of the gland called “suprarenal” instead of “adrenal”?

A

Adrenal= humans, gland positioned ON-TOP of the kidney
Suprarenal= (kidneys are horizontal), gland is INFRONT of the kidney

47
Q

What does the ‘suprarenal’ organ qualify as?

A

double origin organ:
- cortex
- inner medulla

completely different parts, origin and cells –> produce different hormones

48
Q

What is the function of the suprarenal gland medulla and cortex? (simply)

A

medulla: similar to the autonomic nervous system
cortex: hormone producing glands

49
Q

What are the different zones of the supranatal cortex?

A

CAPSULE
1) zona glomerulosa
2) zona fasciculata
3) zona reticularis
ADRENAL MEDULLA

50
Q

State the arrangement of cells in the suprarenal cortex.

A
  • arranged in cords or glomerular
    structures
  • cells: cuboidal/columnar or polygonal
  • 3 zones
  • 4 zones in horses and carnivores
51
Q

State the composition of the zona glomerulosa.

A
  • suprarenal cortex
  • outermost layer
  • outer zone adjacent to the capsule
  • cells arranged in glomeruli or curved
    cords
  • small cells! large nucleus! –> cells look darker!
52
Q

What is the special zone of carnivores and horses? Where is it located? What is it composed of?

A

Zona Intermedia
- small undifferentiated cells
- present between the zona
glomerulosa and zona fasiculata
- in horses and carnivores.

53
Q

State the composition of the zona fasciculata.

A
  • characteristic foamy cytoplasm
    –> large amount of lipid.
  • widest zones
  • larger cells
  • arranged in columns –> linear pattern arrangement
54
Q

State the composition of the zona reticularis.

A
  • smaller cells
  • no specific arrangement
    –> 3D network
  • cytoplasm may have brown pigment–> darker appearance
  • adjacent to the suprarenal medulla
  • innermost zone of the cortex
55
Q

What hormones are produced in the zona glomerulosa? What produces them?

A

Zona glomerulosa cells form ovoid clusters and produce mineralocorticoids (aldosterone).

56
Q

What hormones are produced in the zona fasciculata? What produces them?

A

Zona fasciculata cells are arranged in long straight cords and produce glucocorticoids (cortisol).

stress hormone!

57
Q

What hormones are produced in the zona reticularis? What produces them?

A

Zona reticularis cells are arranged in anastomosing cords produce weak androgens.

58
Q

State the composition of the suprarenal medulla. What is it composed of? What cell populations are present in animals? What do they contain?

A

Medullary Endocrine Cells = Chromaffin Cells
- clear cytoplasm
- modified postganglionic sympathetic neurons

  • In animals, two populations of endocrine cells are recognized based on the
    catecholamines present in cytoplasmic
    membrane-bounded dense granules    .
    contain one of the catecholamines:
  • adrenalin (epinephrine)
  • noradrenalin (norepinephrine),
    + chromogranins (binding proteins for the catecholamines)
59
Q

What is the function of chromogranins? Where are they found?

A
  • in cytoplasmic membrane-bounded dense granules.
  • binding proteins for the catecholamines
60
Q

What surrounds chromaffin cells? How are they arranged?

A
  • arranged in clumps
  • surrounded by sinusoidal capillaries
61
Q

How do chromaffin cells look like?

A
  • clear cytoplasm
  • may appear brown due to the oxidation process
62
Q

What cells are present in the suprarenal gland? How do they look? What are they composed of?

A

Epinephrine cells:
- light chromaffin stains
- majority of medullary cells

Norepinephrine cells:
- dark chromaffin stains
- minority of medullary cells

63
Q

State the structure of pancreatic islets. Other name?

A

Endocrine pancreatic islets = islets of Langerhans:
- scattered among exocrine secretory units.
- clusters of endocrine cells.
- connected by gap junctions (facilitate intercellular communication)

64
Q

Explain Type A pancreatic islets.

A
  • dense cytoplasmic granules.
  • secretes glucagon, cholecystokinin, gastric inhibitory protein and ACTH-endorphin.
65
Q

State the function of type A pancreatic cell secretions.

A
  • Glucagon stimulates glycogen breakdown which increases blood glucose
    levels.
  • Cholecystokinin stimulates contraction of the gallbladder and release of
    pancreatic enzymes.
  • Gastric inihibitory protein inhibits the secretion of gastric acid and pepsin
    and stimulates the release of insulin in the pancreas.
66
Q

Explain Type B pancreatic islets.

A
  • most numerous cell in the islet.
  • produce proinsulin
67
Q

State the function of type B pancreatic cell secretions.

A

During transport from the Golgi apparatus to the cell surface, the proinsulin is converted to insulin.
- The secretory vesicles fuse with the cell membrane, insulin is released, and the hormone enters nearby capillaries.

68
Q

Explain Type D pancreatic islets.

A
  • large
  • pale cytoplasmic granules.
  • secrete: somatostatin and vasoactive intestinal peptide (VIP)
69
Q

State the function of type D pancreatic cell secretions.

A
  • Somatostatin inhibits insulin and glucagon secretion in a local paracrine fashion.
  • VIP induces glycogen break down and stimulates gastrointestinal fluid secretion.
70
Q

State the names of other pancreatic islets. What are their functions?

A

Pancreatic polypeptide cells (PP
cells or F cells):
- increases glycogenolysis and regulates gastrointestinal activity.
G cells.
- stimulates production of gastric
acid by parietal cells in the stomach.

71
Q

State the composition of testis. What cells? What is secreted?

A

Leydig cells = interstitial cells
- found near the seminiferous
tubules in the testicle.
- round/polyhedral
- large nucleus.
- produce testosterone.

72
Q

Is it possible to distinguish between the different pacreatic islet cells?

A

NO!
- but its possible to depict the pancreatic islet themselves

73
Q

State the composition of ovaries. What cells? What is secreted?

A
  • granulosa cells
  • thecal cells
    produce ovarian hormones.

(Other places where estrogens are produced: liver, pancreas, adrenal glands, skin,
brain, adipose tissue etc.)

74
Q

State the composition of the corpus luteum. What cells? What is secreted?

A

The granulosa cells and thecal cells enlarge and transforms to endocrinous cell
populations of the corpus luteum.

Two different types of endocrinous cells:
- Granulated luteocytes (develop from granulosa cells)
- Thecaluteocytes (develop from theca cells)

Produces hormone progesterone

75
Q

State the composition of the adipose tissue. What cells? What is secreted?

A

Produces leptin, adiponectic and resistin
- regulates energy metabolism

Histology (20 decks)

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