Epithelial Tissue

Question 1

What is epithelial tissue and where is it found?

Answer 1

Continuous sheets of cells that cover external and internal surfaces of the body

Question 2

Describe the structure of epithelial tissue (5)

Answer 2

1. Apical surface
2. Tightly packed cells
3. Basal surface
4. Attached to basement membrane, which is connected to loose connective tissue called the lamina propia
5. Avascular (no blood vessels). Nutrients must diffuse in

Question 3

Simple squamous epithelia

• Structure
• Function
• Location

Answer 3

Simple = one layer of cells
Squamous = width is much greater than height, SQUASHED appearance
Absorption, secretion, line surfaces
e.g. Bowman’s capsule, serosa of lungs
NOT found on surfaces subject to abrasion

Question 4

Simple cuboidal epithelia

• Structure
• Function
• Location

Answer 4

Simple = one layer of cells
Cuboidal = approximately square shaped
Absorption, secretion, line surfaces
e.g. Pancreatic duct, kidney tubules

Question 5

Simple columnar epithelia

• Structure
• Function
• Location

Answer 5

Simple = one layer of cells
Columnar = height is greater than width
Secretion, absorption
e.g. Line the crypts of Lieberkuhn in the colon, line the GI tract

Question 6

Stratified squamous epithelia

• Structure
• Function
• Location

Answer 6

Stratified = two or more layers of cells
Multiple layers of cells, and the outermost are squamous
Can be keratinised
Protect against abrasion, prevent water loss but remain moist
e.g. oral cavity, vagina, anal canal
“anywhere you can put a dick”

Question 7

Stratified cuboidal epithelia

• Structure
• Function
• Location

Answer 7

Stratified = two or more layers of cells
Multiple layers of cells, and the outermost are cuboidal
Secretion and absorption
e.g. Salivary glands, mammary glands, sweat glands

Question 8

Stratified columnar epithelia

• Structure
• Function
• Location

Answer 8

Stratified = two or more layers of cells
Multiple layers of cells, and the outermost are columnar
Secretion, protection
e.g. Conjunctiva of the eye (secrete tears), male urethra (protect from urine)

Question 9

Transitional epithelia

• Structure
• Function
• Location

Answer 9

Cells can stretch and change shape when needed. At rest appear cuboidal. When stretched appear squamous.
Allows distension of organs
e.g. lining of the urinary bladder and ureters
When bladder is full, the epithelia lining stretches so it can distend

Question 10

Psuedostratified columnar epithelia

• Structure
• Function
• Location

Answer 10

One layer of cells but nuclei are at different heights along the columnar cells, giving the appearance of multiple cell layers. Usually contain goblet cells and often ciliated.
Line, secrete proteins
e.g. lining of nasal cavity, upper respiratory tract (both ciliated)

Question 11

Describe goblet cells (3)

Answer 11

Cells that are shaped like a goblet
Have microvilli on apical surface instead of cilia
Secrete mucus onto the apical surface of the epithelium
Usually in psuedostratified columnar epithelium