Epithelial Tissue

Question 1

What is the general structure of epithelial tissues?

Answer 1

• 1 layer or more of tightly packed cells, with exposed apical surface and cells attached to the basal membrane (like a carpet)

Question 2

What is the general function of epithelial cells?

Answer 2

• lines surfaces to protect

- forms glands to secrete

Question 3

What are the 4 characteristics of E tissue?

Answer 3

1) cells have polarity
2) layers of tightly packed cells bound together by cell junctions
3) avascular
4) high rate of cell division to replace lost/damaged cells

Question 4

What are the characteristics of E cells?

Answer 4

• apical surface is exposed
• unequal distribution of organelles
• basal surface anchored to underlying connective tissues

Question 5

Why can skin shed off?

Answer 5

• the apical skin has older dead cells which can be rubbed off

Question 6

Why doesn’t skin come off when pulled?

Answer 6

-basal surface of skin Is connected to underlying tissue

Question 7

What is underneath the basal surface?

Answer 7

-protein filaments made by epithelial tissue and underlying connective tissue

Question 8

What are tight junctions?

Answer 8

• interlocking membrane proteins fuse adjacent cell membranes
• prevents molecules moving between cells
  eg. need acidity from eating away at stomach and other tissues

Question 9

What are desmosomes?

Answer 9

• transmembrane proteins reinforced by cytoskeleton
• strong connections resists stretching, twisting
  eg. when you burn the top of your mouth –> skin comes off in “sheets”

Question 10

What are gap junctions?

Answer 10

• channel proteins (connexions) connect cells
• allows for exchange of small molecules, ions
  eg. to coordinate cilia beating upward trachea to keep things out of lungs

Question 11

What does avascular mean?

Answer 11

• no blood vessels present –> never any capillaries or. veins in tissue itself
• exchange of nutrients, waste by diffusion

Question 12

Why is it important for E tissue to have high rates of cell division? Why is this a downfall?

Answer 12

eg. why your skin cells can rejuvenate
- bad because chemotherapy targets cancerous cells that are dividing quickly but will also kills healthy E cells also travelling quickly

Question 13

What is the structure of simple squamous epithelial tissue?

Answer 13

-one layer of flat cells = thin and fragile

Question 14

What is the function of simple squamous E tissue?

Answer 14

-lines protected areas that are not exposed to the outside world

Question 15

Where are simple squamous E tissue found?

Answer 15

• mesothelium lines body cavities
• endothelium lines heart, blood vessels
• walls of alveoli and capillary for gas exchange

Question 16

Why don’t you want bigger cells lining the blood vessels?

Answer 16

-they would take up too much space in the vessel and blood would not be able to get through well

Question 17

What is the structure of simple cuboidal E tissue?

Answer 17

• one layer of cube-shaped cells

- a bit more cytoplasm with spherical nucleus inside the cell

Question 18

What is the function of simple cuboidal E tissue?

Answer 18

-limited protection with more cytoplasm for secretion and absorption

Question 19

Where are simple cuboidal E tissue located?

Answer 19

-lines kidney tubules, pancreatic ducts, salivary glands, forms glands

Question 20

What is the structure of simple columnar E tissue?

Answer 20

• one layer of tall rectangular cells

- lots of cytoplasm with elongated nuclei neat basal surface

Question 21

What is the function of simple columnar E tissue?

Answer 21

• limited protection

- lots of cytoplasm for lots of secretion, absorption

Question 22

Where is simple columnar tissue found?

Answer 22

-forms glands, lines stomach, and intestines

Question 23

What is the structure of stratified squamous tissue?

Answer 23

-many layers of cells, apical layer appears flat

Question 24

What is the function of stratified squamous tissue?

Answer 24

-protects against abrasion, chemicals, pathogens

Question 25

What is the structure, function, and location of keratinized stratified squamous epithelium?

Answer 25

(killed) Struc: apical layers of cells are packed with keratin protein Func: prevents water loss Loc: skin

Question 26

What is the structure, function, and location of non-keratinized stratified squamous epithelium?

Answer 26

(not killed) Struc: no keratin protein so they will dry out, must keep moist Loc: lines oral cavities, vagina, anus, pharynx, esophagus

Question 27

What is the structure of stratified cuboidal E tissue?

Answer 27

-several layers (usually two), apical layer appears cuboidal)

Question 28

What is the function of stratified cuboidal?

Answer 28

-protection and secretion

Question 29

Where are stratified cuboidal tissues found?

Answer 29

-they are rare; forms ducts of sweat, mammary glands

Question 30

What is the structure of stratified columnar?

Answer 30

-several layers of cells, apical layer appears columnar

Question 31

What is the function of stratified columnar?

Answer 31

-protection and secretion

Question 32

Where are stratified columnar E tissues found?

Answer 32

-rare; lines pharynx, vas defends, urethra

Question 33

What is the structure of pseudo stratified ciliated columnar?

Answer 33

- cells vary in size - position of nucleus varies therefore cells look layered - but all cells contact basement membrane

Question 34

What is the function of pseudo stratified ciliated columnar?

Answer 34

-protects, secretes, moves material along passageway

Question 35

Where are pseudo-stratified ciliated columnar tissues found?

Answer 35

-lines nasal cavity, trachea, bronchi, ovarian tubes

Question 36

What is the structure of transitional epithelium?

Answer 36

- cells may be crowded into many layers --> looks stratified cuboidal - cells mat be stretched flat --> looks like simple squamous

Question 37

What is the function of transitional E?

Answer 37

-tolerates stretching, recoil

Question 38

What is the location of E?

Answer 38

-empty vs. full bladder