Epithelium Flashcards

1
Q

Which germ layers is epithelium derived from?

A

All of them

ectoderm, mesoderm, endoderm

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2
Q

What epithelium does the ectoderm give rise to?

A

Epidermis and associated glands (sweat, mammary, sebaceous)

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3
Q

What epithelium does the mesoderm give rise to?

A

Mesothelium (lining of body cavity)

Endothelium (lining of blood vessels)

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4
Q

What epithelium does endoderm give rise to?

A

Respiratory tract
GI tract and associated glands (liver, pancreas)
Urinary bladder

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5
Q

Absorption occurs at the _______ end of an intestinal epithelial cell.

A

Apical

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6
Q

What is the basal lamina?

A

AKA basement membrane
Extracellular boundary between epithelium and underlying connective tissue
Can’t usually resolve with light microscope
Underlies and supports epithelium
Molecular filter in kidney
Tissue segregation in embryo
Cancer cells break through during metastasis

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7
Q

The shape of the ________ often approximates the shape of the cell.

A

Nucleus

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8
Q

Olfactory epithelium also contains what cell type?

A

Sensory nerve cells

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9
Q

What are the 7 main functions of epithelial tissues?

A
  1. Protection
  2. Lubrication
  3. Secretion
  4. Transport
  5. Absorption
  6. Excretion
  7. Sensory Reception
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10
Q

What type of epithelium is involved in lubrication?

A

Mesothelium
(moist epithelium)
Moisture comes from underlying connective tissue.

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11
Q

What are three main ways to classify epithelium?

A
  1. Shape of individual cell (squamous, cuboidal, columnar)
  2. Number of layers of cells (simple, stratified, pseudostratified)
  3. Ability of epithelium to distend (transitional)
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12
Q

How is cell shape determined?

A

Relative dimensions in section perpendicular to basal lamina.

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13
Q

Shape of a cell that extends further along basal lamina than it extends perpendicular to basal lamina

A

Squamous

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14
Q

Shape of a cell that extends along basal lamina about the same that it extends perpendicular to basal lamina

A

Cuboidal

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15
Q

Shape of a cell that extends less along basal lamina than it extends perpendicular to basal lamina

A

Columnar

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16
Q

Classification when every cell touches free space / lumen AND basal lamina. (one layer)

A

Simple

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17
Q

Classification when NO cell touches both free space / lumen and basal lamina. (many layers)

A

Stratified

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18
Q

Classification with all cells touch basal lamina, but only some touch free space / lumen. (2 layers)

A

Pseudostratified

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19
Q

Classification when cells can distend. Found in urinary tract. (3-5 layers)

A

Transitional

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20
Q

What is the structure and function of simple squamous epithelium and where is it found?

A

Thin, material can get across
Endothelium
Mesothelium
Lung alveoli

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21
Q

What is the structure and function of simple cuboidal epithelium and where is it found?

A

Larger cells than squamous due to increased need for cellular machinery
Glands/ducts in pancreas and liver
Sweat glands
Kidney tubules

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22
Q

What is the structure and function of simple columnar epithelium and where is it found?

A
Absorptive or secretory (long nuclei and cells) 
Stomach 
Intestines
Oviduct
Uterus
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23
Q

What is the structure and function of stratified squamous epithelium and where is it found?

A

Many layers, rough and tough
Skin
Esophagus
Mouth

24
Q

What is the structure and function of stratified cuboidal epithelium and where is it found?

A
Sweat gland ducts (dump in stratified skin) 
Sebaceous glands (dump into stratified skin) 
Ovarian Follicles
25
What is the structure and function of stratified columnar epithelium and where is it found?
Pharynx and larynx (rare)
26
What is the structure and function of stratified transitional epithelium and where is it found?
``` Outer cells can distend Urinary bladder Ureter Urethra Male reproductive tract ```
27
What is the structure and function of pseudostratified columnar epithelium and where is it found?
2 layers Trachea Bronchi Epididymis
28
What is the main difference between dry epithelium and moist epithelium? (both stratified squamous)
``` Dry = keratinized Moist = non-keratinized ```
29
_________ contain actin, are about 2 microns long, and function in absorption.
Microvilli
30
________ contain microtubules, are 5-10 microns long, and function to move material along the cell surface.
Cilia
31
_______ contain actin, are up to 30 microns long, and function in hearing ad absorption in the male reproductive tract.
Stereocilia
32
Actin in microvilli comes down to meet a network of actin and myosin known as the _________.
Terminal web
33
What is the main function of microvilli?
Increase absorptive surface area
34
A layer of closely packed microvilli is often termed:
brush or striated border
35
The trachea contains ______ that help move mucus away from the lung.
Cilia
36
What is the structure of a cilium?
9 + 2 microtubule arrangement | Dynein used fro movement
37
Term that refers to "all the way around the cell"
Zonula
38
Term that refers to a point (not all the way around)
Macula
39
The junctional complex (terminal bar) is made up of which three junctions?
``` Zonula occludens (tight junction) Zonula adherens Macula adherens (desmosome) ```
40
What is the function of zonula occludens (tight junctions)?
Occludes extracellular space Prevents diffusion between human and underlying connective tissue (prevents material - undigested food - from going between cells) Barrier to lateral diffusion of plasma membrane proteins
41
What is the function of zonula adherens?
Anchors actin filaments to membrane Maintains cell tone Establishes proper tension at cell junctions
42
What is the function of macula adherens (desmosome)?
Cell-cell adhesion "spot weld" Uses thicker keratin filaments
43
What is the function of macula communicans (gap junctions)?
Intercellular movement of ions and metabolites Communication between adjacent cells (Esp. heart)
44
What is the difference between desmosomes and hemi-desmosomes?
Desmosomes connect neighboring cells | Heme-Desmosomes anchor cell to basal membrane
45
__________ are composed of 6 subunits and make up the open channels between adjacent cells found in gap junctions.
Connexons
46
When might a gap junction channel rotate to close and become inactive?
When the cell dies
47
If an __________ gland forms, connecting cells persist for form the duct. (Deepest cells become secretory)
Exocrine
48
If an ___________ gland forms, connecting cells disappear. (Deepest cells remain to secrete into capillaries)
Endocrine
49
What are the different types and classification of exocrine glands?
Can be unicellular (goblet cells) | Can be multicellular (alveolar/acinar or tubular)
50
What is the structure and function of a goblet cell?
Produces mucus and secretes directly onto surface Flat nucleus Usually stains palely with a "foamy" appearance Glands with a lot of goblet cells = simple tubular glands
51
A ___________ gland secretes non viscous, proteinaceous secretion (enzymes), sometimes contains secretion granules (pancreatic acinar cells)
Serous gland
52
A ________ gland secretes viscous, proteins-polysaccharides, lubricating function, often pale staining with H & E (Goblet cell)
Mucous
53
Most glands use the _________ mode of secretion. The cell remains intact during the secretory process. Exocytosis. (Simple epithelium)
Merocrine = Eccrine
54
Mammary glands use the _________ mode of secretion. The apex of the cell is secreted along with secretory product. (Simple epithelium)
Apocrine
55
The sebaceous gland uses the __________ mode of secretion. The entire cell is secreted. (Stratified epithelium)
Holocrine
56
How can glands be classified?
By secretory portion shape: tubular, flasklike (alveolar or acinous), or both (tubule-alveolar) By duct branching: no branching (simple), branching (compound)