Epithelial Tissue

Question 1

What are the features of the apical surface of an epithelial cell?

Answer 1

Exposed

Specialised with: microvilli, cilia

Question 2

What are the features of the basal surface of an epithelial cell?

Answer 2

Attaches to the basement membrane via:

Integrins

Question 3

What is the basement membrane?

Answer 3

Thin layer of basal lamina (and reticular fibres) secreted by epithelial cells between them and connective tissue

Question 4

How do epithelial cells attach to the basement membrane?

Answer 4

Hemidesmosomes and focal adhesions use integrins as transmembrane proteins between the cell and the basement membrane

Question 5

What are integrins?

Answer 5

Transmembrane proteins that attach cells to the basement membrane and through to the Extracellular Matrix.
Also, facilitate cell migration (immune patrolling) and cell signalling.

Question 6

How do hemidesmosomes attach to the basement membrane

Answer 6

Hemidesmosomes produce transmembrane proteins (integrins) that interlock and connect cells with the basement membrane

Question 7

How do focal adhesions attach to the basement membrane?

Answer 7

Focal adhesions anchor Intracellular actin filaments (microfilaments) to transmembrane proteins (integrins) which connect the cell to the basement membrane

Question 8

What are the features of the lateral surface of an epithelial cell?

Answer 8

Attaches to adjacent cells via:
Tight junctions
Desmosomes
Gap junctions

Question 9

How do tight junctions attach to adjacent cells?

What purpose does this serve?

Answer 9

Protein complexes fuse the membranes together forming a seal.
Molecules have to pass through cells

Question 10

How do desmosomes attach to adjacent cells?

What purpose does this serve?

Answer 10

Produces transmembrane proteins (cadherins) that interlock and connect cells (also contain intermediate filaments intracellularly)
Helps strengthen the connections at other junctions and prevent stretching/twisting of cells under stress

Question 11

How do gap junctions attach to adjacent cells?

What purpose does this serve?

Answer 11

Connexons (lined up transmembrane proteins) form channels between cells
Allows the movement of molecules for cell-to-cell communication

Question 12

What are the 4 types of simple (single-level) epithelial cells?

Answer 12

Squamous
Cuboidal
Columnar
Psuedostratified

Question 13

What are the 4 types of stratified (multi-level) epithelial cells?

Answer 13

Squamous
Cuboidal
Columnar
Transitional

Question 14

Where is simple squamous epithelium found and what is it’s specific function?

Answer 14

Acts as a barrier: endothelium of vascular vessels, Bowman capsule
Secretes lubricating fluid: mesothelium
Active transport/gas exchange: type I pnuemocytes

Question 15

Where is simple cuboidal epithelium found and what is it’s specific function?

Answer 15

Diffusion and secretion for hormones: thyroid (thyroxine), type II pnuemocytes (surfactant)
Line ducts/follicles for exocrine glands

Question 16

Where is simple columnar epithelium found and what is it’s specific function?

Answer 16

Contain microvilli for absorption (simple columnar —> villi): alimentary/GI tract

Question 17

Where is psuedostratified epithelium found and what is it’s specific function?

Answer 17

Traps particle; secretes mucous (goblet cells), wafts cilia (ciliated epithelial cells): respiratory tract

Question 18

Where is non-keratinised stratified squamous epithelium found and what is it’s specific function?

Answer 18

Reduces water loss (remains hydrated) and protects against abrasion: openings of the skin (mouth, nostrils, anus)

Question 19

Where is keratinised stratified squamous epithelium found and what is it’s specific function?

Answer 19

Greatly reduces water loss and toxic ingress
Protects against abrasion and microbial colonisation
Found on the outer layers of skin (stratum corneum) - cornified layer of keratin

Question 20

Where is stratified transitional epithelium found and what is it’s specific function?

Answer 20

Stretches and distends: relaxed (columnar) contracted (squamous)
Protects from toxic chemicals
Found in the urinary tract

Question 21

What surfaces is epithelium tissue found?

Answer 21

Exterior (skin)
Interior open to the exterior (mucous membranes)
Interior closed to the exterior (serous membranes)

Question 22

Where are mucous membranes found?

Answer 22

Mucosa of:

Digestive tract
Respiratory tract
Urinary tract

Question 23

Where are serous membranes found?

Answer 23

Viscera of:

Peritoneum
Pleural sacs
Peritoneum

Question 24

Describe features of mucous membranes

Answer 24

Single-layered
Inner epithelium lines lumen
Surrounded by lamina propria (connective tissue) and muscularis mucosae

Question 25

Describe features of a serous membrane?

Answer 25

Double-layered (mesothelium)
Inner epithelium secretes lubricating fluid (for viscera)
Surrounded by lamina propria (connective tissue)