Epithelial Tissues

Question 1

What are epithelial tissues?

Answer 1

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

Question 2

What are the 2 major types of epithelial tissue?

Answer 2

• Surface

- Glandular

Question 3

What is surface epithelial tissue?

Answer 3

• Covers or lines the body surfaces, tubes and cavities

- Forms boundaries between different environments

Question 4

What is glandular epithelial tissue?

Answer 4

• Primarily involved in secretion
• Exocrine glands
• Endocrine glands

Question 5

What are the characteristics of epithelial tissue?

Answer 5

• 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

Question 6

What are the functions of epithelial tissue?

Answer 6

• Physical protection
• Diffusion
• Absorption
• Secretion

Question 7

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

Answer 7

• Skin and oral cavity

Question 8

Where in the body does epithelial tissues use diffusion?

Answer 8

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

Question 9

Where in the body does epithelial tissues use absorption?

Answer 9

• Nutrients from GIT

Question 10

Where in the body does epithelial tissues use secretion?

Answer 10

• Sweat
• Mucus
• Enzymes

Question 11

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

Answer 11

• Number of layers
• Cell shape
• Specialisations

Question 12

What are SIMPLE epithelia?

Answer 12

• One layer of cells

- Diffusion/absorption/ secretion

Question 13

What are STRATIFIED epithelia?

Answer 13

• Two or more layers

- Physical protection against mechanical stress

Question 14

What are PSEUDOSTRATIFIED epithelia?

Answer 14

• Single layer of cells that appear stratified

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

Question 15

What is a squamous cell?

Answer 15

• Cells are flat

- Width greater than height

Question 16

What is a cuboidal cell?

Answer 16

• Cells appear square

Question 17

What is a columnar cell?

Answer 17

• Height is greater than width

Question 18

What is a transitional cell?

Answer 18

Changes shape to accommodate stretching

Question 19

What are microvilli?

Answer 19

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

Question 20

What are cilia?

Answer 20

• Long motile projections that beat rhythmically

Question 21

What is keratin?

Answer 21

• Confers mechanical strength

- Good for physical protection

Question 22

What is the function and location of simple squamous cells?

Answer 22

Function - lines surfaces involved in passive diffusion

Location - Lungs (gases), capillaries (fluids)

Question 23

What is the function and location of simple cuboidal cells?

Answer 23

Function - Lines small ducts and tubules

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

Question 24

What is the function and location of simple columnar cells?

Answer 24

Function - Lines absorptive surfaces

Location - Small intestine (note presence of microvilli)

Question 25

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

Answer 25

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

Location - Female reproductive tract

Question 26

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

Answer 26

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

Location - Airways of respiratory tract

Question 27

What are goblet cells and what do they secrete?

Answer 27

• Modified columnar epithelial cells

- Synthesise and secrete mucus

Question 28

Where are goblet cells located?

Answer 28

Scattered through simple columnar epitheliums

• Respiratory
• Gastrointestinal

Question 29

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

Answer 29

The level of physical stress

Question 30

What are stratified epithelia named after?

Answer 30

The shape of the cells at the apical surface

Question 31

How do stratified epithelial cells mature?

Answer 31

From basal layer from continuously dividing stem cells

Question 32

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

Answer 32

Anucleate squames - a thin cell lacking a nucleus

Question 33

What is the function and location of stratified squamous cells?

Answer 33

Function -

• Protection
• Non-keratinised (moist)
• Keratinised

Location -

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

Question 34

What is the function and location of stratified cuboidal cells?

Answer 34

Function - secretory

Location - Secretory ducts of exocrine glands, such as salivary

Question 35

What is the function and location of stratified columnar cells?

Answer 35

Function - secretory and protective

Location - Male urethra and lining some glands

Question 36

What is the function and location of transitional cells?

Answer 36

Function - Allows for expansion and stretch

Location - Bladder

Question 37

What is the function of keratin?

Answer 37

Enhances resistance to physical stress

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

Question 38

What is a carcinoma?

Answer 38

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

Question 39

What is epithelial dysplasia?

Answer 39

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