Epithelial Tissues

Question 1

What is a ‘tissue’ ?

Answer 1

• A collection of cells and their products organised to perform a certain function.
• Various cell types work together to form a tissue.
• Tissues then organise with one another to form the body organs.

Question 2

The four types of tissues

Answer 2

1) Connective
2) Muscle
3) Neural
4) Epithelial (the focus of this deck)

Question 3

What do epithelial tissues do?

Answer 3

• Protect exposed portions of the body’s organs and safeguard them from abrasion and injury.
• Control the passage of materials from the outside environment to the specialised body cells.

Question 4

Where are epithelial tissues found?

Answer 4

At the surface of body organs.

Question 5

Basement membrane

Answer 5

• Epithelial tissues are attached here.
• The two layers are ‘basal lamina’ and ‘reticular lamina’

Question 6

Depending on the number of layers of cells, epithelial tissues can either be…

Answer 6

1) Simple (i.e. just one layer of cells);
2) Stratified (i.e. cells stacked on one another); or
3) Pseudostratified (i.e. unique shaped cells that look like they are multilayered)

Question 7

Depending on the shape and number of layers of cells, epithelial tissues can either be…

Answer 7

1) Simple squamous
2) Simple cuboidal
3) Simple columnar
4) Stratified squamous
5) Stratified cuboidal
6) Stratified columnar
7) Pseudostratified columnar

Question 8

Simple squamous epithelial tissue

Answer 8

• Single layer of flat cells
• Nuclei is at the centre of the cells
• Lines blood vessels, air sacs of the lungs, portions of the kidney
• Endothelium = in heart and blood vessels
• Mesothelium = in abdominal cavities

Question 9

Simple cuboidal epithelial tissue

Answer 9

• Single layer of cube-shaped cells
• Nuclei is at the centre of the cells
• Found in kidney tubules, excretory ducts of the glands
• Secretes various substances
• Used for protection

Question 10

Simple columnar epithelial tissue

Answer 10

• Single layer of tall, cylindrical cells
• Nuclei is at the base of the cells
• Found in gastrointestinal tract (from stomach to anus), ducts of many glands.

Question 11

Pseudostratified columnar epithelial tissue

Answer 11

• All cells have contact with the basement membrane
• Layers (i.e. stratification) does not truly occur, but resemble stratification
• Has cilia at it’s surfaces
• Found in nasal cavities, windpipe, bronchi

Question 12

Stratified squamous epithelial tissue

Answer 12

• Multiple layers of flat cells
• Found where stress is severe (i.e. lining of the stomach, oesophagus, terminal surface of the tongue)
• Main function = protection

Question 13

Stratified columnar epithelial tissue

Answer 13

• Multiple layers of tall, cylindrical cells
• Found in portions of the pharynx, some excretory ducts
• Rare
• Main function = protection

Question 14

Stratified cuboidal epithelial tissue

Answer 14

• Multiple layers of cube-shaped cells
• Rare
• Found along ducts of sweat glands in skin, certain ducts of mammary glands
• Function = protect underlying cells and tissues

Question 15

Transitional epithelial tissue

Answer 15

• Contains a variety of cells, ranging from squamous, cuboidal and columnar cells.
• Found in the urinary bladder
• Stretches to allow distension of the urinary bladder when it fills with urine
• After urine is discharged, the transitional epithelium contracts and assumes a compacted appearance.