Epithelia

Question 1

What are epithelia

Answer 1

They form a continuous sheet of cells. They are specialised for distinct functions

Question 2

What is the function of epithelia

Answer 2

They act as barriers between the body and the external world and between fluid compartments within the body. They also transport molecules via absorptive processes

Question 3

What is simple cuboidal epithelium

Answer 3

A single layer of cube cells. Have a central nuclei

Question 4

What is the function of simple cuboidal epithelium

Answer 4

Secretion and absorption

Question 5

What is the localisation of simple cuboidal epithelium

Answer 5

Kidney tubules, ducts, secretory portions of small glands and ovary surface

Question 6

What is simple columnar epithelium

Answer 6

Basal nuclei and ciliated/non ciliated with microvilli

Question 7

What is the function of simple columnar epithelium

Answer 7

Absorption and secretion of mucus and enzymes

Question 8

What is the localisation of simple columnar epithelium

Answer 8

Non ciliated: digestive tract, gallbladder and excretory ducts. Ciliated: small bronchi and uterine tubes

Question 9

What is simple squamous epithelium

Answer 9

Flat cells with disc-shaped nuclei

Question 10

What is the function of simple squamous epithelium

Answer 10

Passage of materials by diffusion and filtration. Secretion of lubricating substances

Question 11

What is the localisation of simple squamous epithelium

Answer 11

Kidney glomeruli, alveoli of lungs and blood vessels

Question 12

What is simple pseudostratified epithelium

Answer 12

They look like there are multiple layers but all cells are in contact with the extracellular matrix. Several layers of nuclei. It is ciliated and non-ciliated

Question 13

What is the function of simple pseudostratified epithelium

Answer 13

Secretion of mucus

Question 14

What is the localisation of simple pseudostratified epithelium

Answer 14

Non ciliated: vas deferens and large glands
Ciliated: trachea and upper respiratory tract

Question 15

What is stratified cuboidal epithelium

Answer 15

Generally 2 layers of cuboidal cells

Question 16

What is the function of stratified cuboidal epithelium

Answer 16

Protects underlying tissue

Question 17

What is the localisation of stratified cuboidal epithelium

Answer 17

Largest ducts of sweat glands and mammary glands

Question 18

What is stratified columnar epithelium

Answer 18

Several cell layers. Basal cells usually cuboidal. Superficial cells are elongated and columnar

Question 19

What is the function of stratified columnar epithelium

Answer 19

Protection and secretion

Question 20

What is the localisation of stratified columnar epithelium

Answer 20

Urethra and conjunctiva of eyes

Question 21

What is transitional epithelium

Answer 21

Several cell layers. Resembles stratified squamous and stratified cuboidal epithelium. Basal cells are cuboidal/columnar. Superficial cells are dome-shaped or squamous-like depending on stretch

Question 22

What is the function of transitional epithelium

Answer 22

Stretches readily permitting distension of urinary organ

Question 23

What is the localisation of transitional epithelium

Answer 23

Ureter, bladder, parts of urethra

Question 24

What is the function of junctional proteins

Answer 24

They connect cells to each other and to basement membrane. Some allow intercellular communication eg. transport of ions. Also, enable polarisation

Question 25

What are tight junctions

Answer 25

They are the most apical junction. They are a branching network of protein strands

Question 26

What is the function of tight junctions

Answer 26

"Zipper" together neighbouring epithelial cells. Defines apical/basolateral boundary. Prevent passage of molecules and ions

Question 27

What are adhering junctions

Answer 27

More basal than tight junctions. A "belt" that encircles epithelial cell directly beneath the tight junction

Question 28

What is the function of adhering junctions

Answer 28

They allow cell-cell adhesion via interaction between extracellular domain

Question 29

What are desmosomes

Answer 29

They are spot like adhesions arranged on the lateral surface of cells

Question 30

What is the function of desmosomes

Answer 30

They allow cell-cell adhesion via interaction between extracellular domains

Question 31

What are gap junctions

Answer 31

Lateral edges of epithelial cells

Question 32

What is the function of gap junctions

Answer 32

Allow intercellular communication

Question 33

What are hemidesmosomes

Answer 33

They are localised to the basal surface

Question 34

What is the function of hemidesmosomes

Answer 34

They attach epithelial cells to the basement membrane

Question 35

What are microvilli

Answer 35

The apical surface area can be increased by presence of a "brush border membrane"

Question 36

What is the function of microvilli

Answer 36

They enable absorption

Question 37

What can increase the basolateral surface area

Answer 37

Lateral interdigitations and basal foldings

Question 38

What is important about the basolateral surface

Answer 38

It is important for transport across the epithelial layer

Question 39

What are cilia

Answer 39

They are found on the apical surface of some epithelia. They are larger than microvilli

Question 40

What is the function of cilia

Answer 40

They move back and forth to move particles

Question 41

What is stratified squamous epithelium

Answer 41

Thick membrane composed of multiple cell layers. Superficial portion of cells are squamous “flattened”. Basal cells are cuboidal/columnar and metabolically active

Question 42

What is the function of stratified squamous epithelium

Answer 42

Protects underlying tissue