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Histology (Emily) > Lecture 3 - Epithelium > Flashcards

Lecture 3 - Epithelium Flashcards

1
Q

Epithelium

A

Close apposition of cells, presence at free surface. All external/internal surfaces, skin, lining tracts and body cavities, lungs, pericardial, peritoneal (abdomen)

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2
Q

Mesothelium

A

Lines pleural (lungs), pericardial (heart) and peritoneal (abdomen) cavities.

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3
Q

Endothelium

A

Lines blood and lymph vessels.

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4
Q

Endocardium

A

Lines ventricles and atria or heart (Usually simple squamous).

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5
Q

Secretory epithelium

A

lines glands

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6
Q

What is the only surface not lined by epithelial cells?

A

lining of joints

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7
Q

Function of epithelial cells

A

protection receptor (skin, taste buds, olfactory epithelium in nasal mucosa, retina of eye) secretion (glands) transport (ciliated) absorption (GI tract)

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8
Q

Epithelial cells are vascular or avascular

A

Avascular; no tubes/vessels for blood/lympathic cells; receive nutrients via diffusion/active transport

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9
Q

Apical Domain

A

Directed towards lumen/free surface, communicates w/ external environment; contains modifications like cilia/villi to help the function of epithelium type.

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10
Q

Lateral Domain

A

Has junctions that hold cells together and communicate with neighboring cells.

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11
Q

Basal Domain

A

Bottom of cells. Binds onto basal lamina (EM) or basement membrane (LM), which is anchored into the CT.

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12
Q

Basement Membrane Make-up

A

Made up primarily of Collagen Type IV. The underlying reticular fibers are made up of and linked to BM by Collagen Type III. Proteoglycans fill up the most volume in BM and are anionic = regulate passage of molecules.

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13
Q

What are blisters?

A

Separation between the basement membrane and underlying connective tissue.

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14
Q

In situ Carcinoma in Epithelium

A

Basement membrane is still in tact. Typically easier to treat.

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15
Q

Invasive

A

Basement membrane breached, enters connective tissue (lymphocytes enter epithelium tissue to fight it from penetrating deeper)

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16
Q

Simple Squamous

A

Function: For exchange, lubrication, and barrier Found in: - vascular system (endothelium) - body cavities (mesothelium) - parietal layer of Bowman’s capsule - respiratory spaces in lung

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17
Q

Simple cuboidal

A

Function: for absorption, barrier, secretion Found in: - exocrine ducts - ovary germinal epithelium - kidney tubules - thyroid particles

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18
Q

Simple columnar

A

Function: absorption and secretion Found in: - small instestine - colon - stomach lining - Gastric glands - gallbladder

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19
Q

Pseudostratified columnar

A

Is a simple epithelium with all cells attached to BM, but some cells do not reach the free surface Found in: - trachea - bronchial tree - ductus deferens - epididymis

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20
Q

Stratified cuboidal

A

Common in sweat grland ducts, large exocrine ducts, anorectal junction

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21
Q

Stratified Columnar

A

Very rare; largest ducts of exocrine glands, anorectal junction

22
Q

Transitional epithelium

A

Stratified, liner ureter/urinary bladder/urethra, bottom layer looks cuboidal but dome shaped cells on the surface that expand

23
Q

Two types of Stratified Squamous Epithelium

A
  1. Non-keratinized: viable top layer, nucleated, found in wet areas (mucous) 2. Keratinized: no nuclei, dead, dry areas (skin)
24
Q

Epithelial Metaplasia

A

reversible process of one mature epithelium converting to another type, e.g. columnar to squamous (“squamous metaplasia”) in trachea or bronchi / squamous to columnar in Barrett’s esophagus and cervical cancer

25
Q

Cigarette smoke change in epithelium?

A

Pseudostratified columnar in trachea/bronchi change to stratified squamous to protect against carcinogen! Not good, because stratified layer would impeded gas exchange.

26
Q

Barrett’s metaplasia?

A

Acid reflux damages the esophagus, so the cells turn from stratified squamous to columnar; cells turn more stomach-like to withstand the damage. More susceptible to adenocarcinoma, because these cells are like glandular cells, producing mucous.

27
Q

Microvilli

A

finger-like cytoplasmic processes extending from the apical surface of cells; “striated border” in LM, for absorption (GI tract), “brush border” in kidneys = FOR ABSORPTION

28
Q

What are all the different fillaments that make up microvilli?

A
29
Q

Stereocilia

A

Unusually long immotile microvilli (sterovilli) for specialized sensitivity, NOT ABSORPTION

Found in: Epidydimus, Ductus Deferens, Inner Ear Hair Cells

30
Q

Cilia

A

Short, thick and motile—moves fluids and particles; found in Trachea, bronchi, uterine tubes

Structure: Axoneme (core) has 9 microtubule doublets and two singlets in the middle, Dynein connects doublets to eachother, Nexin links between doublets.

31
Q

Basal body

A

9 triplets with no center microtubles, base of axoneme. (9+0 pattern)

32
Q

Patient has mutation in genes that code for dynein. What is a possible symptom?

A

Reccurent sinus and pulmonary infections! Without dynein = immotile cilia syndrome = cannot move debris out of the way

33
Q

Primary (Mono) Cilia

A

immotile (no dynein arms), 9+0 sturcutre, one per cell, sensory role (fluid bends the cilia, which initiates cellular calcium influx) with membrane G-protein coupled receptors, Na+ Ca2+ channels

34
Q

Zonula Occludens

A

tight junction, seals space b/t cells; located at most apical point, impermeable/control passage btw cells.

Homophilic interactions: protein on one side binds with same type in other cell

35
Q

Proteins in Zonula Occludens

A

Occludens, claudins, JAMS

(claudins are looser)

36
Q

Anchoring Junctions

A

Ca++ dependent, protein accumulations next to membrane; mechanical stability by linking cytoskeleton of adjacent cells (to both actin and intermediate filaments)

37
Q

Zonula Adherens

A

zone/belt connects adjacent cells, below zonule occludens

  • linked with actin filaments of terminal web via homotypic or hemophilic binding
38
Q

Cadherins

A

Integral membrane proteins that link cell-to-cell via Ca++ in Anchoring Junctions (ZA and MA)

39
Q

Macula Adherens (Desmosome)

A

Very strong as it connects intermediate filaments (more stable)! Like ZA, uses cadhereins (desmocollins, desmogleins) and has intracellular plaque proteins where intermediate filaments attach.

40
Q

Three zones of a apical region

A

ZO (Zona Occludens)

ZA (Zona Adherens)

MA (Macula Adherens)

41
Q

Communicating Junctions

A

For communication, NOT structure

Gap Junctions: connexin protein lines up with connexin protein in neighbor cell to form a channel à connexon (Ca2+ regulated)

42
Q

Basal Domain Junctions

A

Anchor cell to extracellular matrix/connective tissue; at the most bottom of cell

  1. Focal Adhesions
  2. Hemidesmosomes
43
Q

Focal Adhesions

A

Integrins attach actin filaments via peripheral proteins. On the other side, they attach to fibronectin in the basement membrane (CT). Very dynamic—quickly form or dissolve and interact with stress fibers = important role in cell movement and migration.

44
Q

Hemidesmosomes

A

Integrins, collagen XVII sits within cell membrane and attach to intermediate filaments via intracellular plaque. Collagen IV and laminin help integrins anchor into collagen matrix

45
Q

Exocrine glands

A

Secrete directly onto surface or via epithelial ducts connected to surface. Three types:

  1. Merocrine Secretion
  2. Apocrine Secretion
  3. Holocrine Secretion
46
Q

Merocrine secretion

A

Membrane bound vesicles fuse with apical surface of cell and release particles via exocytosis (most common, e.g. pancreatic acinar cells)

47
Q

Apocrine secretion

A

secretory product released from cell still enclosed in plasma membrane; good for large production, e.g. lactating mammary gland (large lipid droplets), skin, ciliary glands of eye lid, and external auditory meatus glands.

48
Q

Holocrine secretion

A

release upon programmed cell death/lysis (sebaceous glands of skin, tarsal glands of eyelid)

49
Q

Difference between endocrine glands and paracrine glands

A

Endocrine glands: no duct system; secrete into connective tissue–>blood stream–>target cells.

Paracrine glands: secretion only affects other cells within same epithelium via diffusion.

50
Q

What enzymes would cancer cells use to invade?

A

Type IV collagenase to break thru basement membrane and metalloproteinase to break all type of collagen

Histology (Emily) (8 decks)

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