Epithelial Tissues Flashcards

1
Q

What are epithelial tissues?

A

A diverse group of tissues that provides structural and functional barrier between biological compartments

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2
Q

What are the 2 major types of epithelial tissue?

A
  • Surface

- Glandular

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3
Q

What is surface epithelial tissue?

A
  • Covers or lines the body surfaces, tubes and cavities

- Forms boundaries between different environments

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4
Q

What is glandular epithelial tissue?

A
  • Primarily involved in secretion
  • Exocrine glands
  • Endocrine glands
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5
Q

What are the characteristics of epithelial tissue?

A
  • Continuous sheets of cells tightly bound together
  • Supported by a basement membrane
  • Epithelial cells are POLARISED:
  • Structurally and functionally distinct cell surfaces
  • Basal surface attached to (or facing towards) BM
  • Apical surface not attached to cells (free)
  • Form structural and functional barrier
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6
Q

What are the functions of epithelial tissue?

A
  • Physical protection
  • Diffusion
  • Absorption
  • Secretion
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7
Q

Where in the body does epithelial tissues act as physical protection?

A
  • Skin and oral cavity
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8
Q

Where in the body does epithelial tissues use diffusion?

A
  • Transfer of gases, nutrients and waste between blood and surrounding surfaces
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9
Q

Where in the body does epithelial tissues use absorption?

A
  • Nutrients from GIT
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10
Q

Where in the body does epithelial tissues use secretion?

A
  • Sweat
  • Mucus
  • Enzymes
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11
Q

What are the 3 main criterial of epithelial tissue that is related to their function?

A
  • Number of layers
  • Cell shape
  • Specialisations
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12
Q

What are SIMPLE epithelia?

A
  • One layer of cells

- Diffusion/absorption/ secretion

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13
Q

What are STRATIFIED epithelia?

A
  • Two or more layers

- Physical protection against mechanical stress

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14
Q

What are PSEUDOSTRATIFIED epithelia?

A
  • Single layer of cells that appear stratified

- Nuclei are at different heights and not all cells reach apical surface

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15
Q

What is a squamous cell?

A
  • Cells are flat

- Width greater than height

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16
Q

What is a cuboidal cell?

A
  • Cells appear square
17
Q

What is a columnar cell?

A
  • Height is greater than width
18
Q

What is a transitional cell?

A

Changes shape to accommodate stretching

19
Q

What are microvilli?

A
  • Tiny projections of the plasma membrane
  • Increase apical surface area
  • Good for absorption
20
Q

What are cilia?

A
  • Long motile projections that beat rhythmically
21
Q

What is keratin?

A
  • Confers mechanical strength

- Good for physical protection

22
Q

What is the function and location of simple squamous cells?

A

Function - lines surfaces involved in passive diffusion

Location - Lungs (gases), capillaries (fluids)

23
Q

What is the function and location of simple cuboidal cells?

A

Function - Lines small ducts and tubules

Location - Collecting tubules of kidneys, Small ducts of salivary glands

24
Q

What is the function and location of simple columnar cells?

A

Function - Lines absorptive surfaces

Location - Small intestine (note presence of microvilli)

25
Q

What is the function and location of ciliated simple columnar cells?

A

Function - Ciliary action facilitates transport of ovum from ovary to uterus

Location - Female reproductive tract

26
Q

What is the function and location of pseudostratified columnar ciliated cells?

A

Function - Ciliary action propel surface layer of mucus containing trapped particles towards pharynx

Location - Airways of respiratory tract

27
Q

What are goblet cells and what do they secrete?

A
  • Modified columnar epithelial cells

- Synthesise and secrete mucus

28
Q

Where are goblet cells located?

A

Scattered through simple columnar epitheliums

  • Respiratory
  • Gastrointestinal
29
Q

What does the number of cells in stratified epithelia relate to?

A

The level of physical stress

30
Q

What are stratified epithelia named after?

A

The shape of the cells at the apical surface

31
Q

How do stratified epithelial cells mature?

A

From basal layer from continuously dividing stem cells

32
Q

Stratifies epithelia cells gradually migrate to the surface and shed. What in the name of these shedded cells?

A

Anucleate squames - a thin cell lacking a nucleus

33
Q

What is the function and location of stratified squamous cells?

A

Function -

  • Protection
  • Non-keratinised (moist)
  • Keratinised

Location -

  • Soft mucosal tissues in oral cavity, pharynx
  • Epidermis, gingival tissues
34
Q

What is the function and location of stratified cuboidal cells?

A

Function - secretory

Location - Secretory ducts of exocrine glands, such as salivary

35
Q

What is the function and location of stratified columnar cells?

A

Function - secretory and protective

Location - Male urethra and lining some glands

36
Q

What is the function and location of transitional cells?

A

Function - Allows for expansion and stretch

Location - Bladder

37
Q

What is the function of keratin?

A

Enhances resistance to physical stress

  • Epithelial cells accumulate keratin filaments as they mature
  • Formation of tough, non-living surface layer
38
Q

What is a carcinoma?

A
  • Malignant tumour arising from epithelial tissue
  • Subclassified by tissue of origin
  • Squamous cell carcinoma resembles stratified squamous epithelium
  • Adenocarcinomas originate/ resemble glands
39
Q

What is epithelial dysplasia?

A
  • A disorder of differentiation of epithelial cells which may regress, remain stable or progress to invasive carcinoma
  • Can invade and destroy adjacent tissues