epithelial tissues

Question 1

where are epithelial tissues found?

Answer 1

lining all body surfaces (epidermis) and all internal tubes and cavities

Question 2

what are the functions of epithelial tissue?

Answer 2

• protective barrier (skin) to prevent substances entering/leaving the body (protects against microbial invasion)
• acts as a continuous boundary between different environments
• provides opportunity to regulate movement of substances
• diffusion in lungs and capillaries
• absorption in the GIT
• secretion in glands/ ducts

Question 3

what is the general arrangement of epithelia?

Answer 3

continuous sheet of tightly bound cells with lateral surfaces adhered to each other

• epithelial cells are polarised along the apical/basal axis

Question 4

what is a tight junction?

Answer 4

• epithelial cells create an impermeable seal between adjacent cells to prevent liquid escaping
• this prevents water passage and allows a layer of cells to act as an impermeable barrier

Question 5

what is an example of a tight junction location?

Answer 5

epithelium lining the bladder to prevent urine leaking into the extracellular space

Question 6

what are desmosomes?

Answer 6

strong adhering junctions between membranes of adjacent cells, anchoring them together
- they ensure epithelial tissues can stretch while remaining in contact

Question 7

what are the three ways in which epithelial tissue structure can differ?

Answer 7

• shape
• number of cell layers
• apical specialisations

Question 8

what are the different shapes of epithelial cells?

Answer 8

• squamous
• cuboidal
• columnar

Question 9

what are the names for the different number of cell layers in epithelium?

Answer 9

• simple- single layer of cells- selective diffusion/secretion/absorption
• stratified- 2 or more layers of cells

Question 10

what are the apical specialisations of epithelial cells?

Answer 10

• microvilli
• cilia
• keratin

Question 11

what do microvilli do to epithelial cells?

Answer 11

increase the apical surface layer

Question 12

what do cilia do to epithelial cells?

Answer 12

assist the movement of particular matter

Question 13

what does keratin do to epithelial cells?

Answer 13

adds a strong protective apical layer

Question 14

what is the function of simple squamous epithelia

Answer 14

lines the surfaces involved in passive diffusion

Question 15

where is simple squamous epithelia located?

Answer 15

in the lungs (alveoli) and capillaries (where its called endothelium)

Question 16

what is the function of simple columnar epithelium?

Answer 16

lines small ducts and tubules involved in absorption and secretion

Question 17

where is simple cuboidal epithelium found?

Answer 17

renal tubes and small ducts of salivary glands

Question 18

what is the function of simple columnar epithelium?

Answer 18

lines absorptive surfaces

Question 19

where is simple columnar epithelium located?

Answer 19

small intestine

Question 20

what is the function of ciliated simple columnar epithelium?

Answer 20

transports ovum from ovary to uterus

Question 21

where is ciliated simple columnar epithelium located?

Answer 21

the female reproductive tract

Question 22

where is the apical surface?

Answer 23

faces the external surface

Question 24

what is the function of simple ciliated pseudostratified columnar epithelium?

Answer 24

propels the surface layer of mucus containing trapped particles towards the pharynx

Question 25

where is ciliated simple pseudo stratified columnar epithelium located?

Answer 25

airways of the respiratory system

Question 26

what does pseudo stratified mean?

Answer 26

the nuclei of the cells are at random locations within the cell giving the false impression that there is multiple layers

Question 27

what are goblet cells?

Answer 27

modified columnar epithelial cells which synthesis and secrete mucus

Question 28

where are goblet cells found?

Answer 28

scattered throughout simple columnar epithelium- repertory/gastrointestinal

Question 29

what is the function of stratified cuboidal epithelium?

Answer 29

secretory

Question 30

where is stratified cuboidal epithelium located?

Answer 30

it is rare- located in some secretory ducts

Question 31

what is the function of stratified columnar epithelium?

Answer 31

secretory and protective

Question 32

where is stratified columnar epithelium located?

Answer 32

it is rare- in the male urethra and lining and in some glands

Question 33

describe stratified squamous epithelia

Answer 33

- gives protection from mechanical abrasion - cells mature from basal layer from dividing stem cells - cells migrate to the apical surface layer - the cells appear cuboidal at the basal layer but are just really active, they are squashed into their known squamous shape as they migrate

Question 34

where is stratified squamous epithelium located?

Answer 34

the epidermis and oral cavity

Question 35

what are the two specialisations that stratified squamous epithelium can be?

Answer 35

keratinised or non-keratinised

Question 36

where does keratin form on epithelium?

Answer 36

the apical surface

Question 37

what is the function of keratin

Answer 37

enhances resistance to physical stress - keratin is non living (no nuclei)

Question 38

where are keratinised epithelium found?

Answer 38

protected surfaces eg epidermis

Question 39

what is transitional epithelium?

Answer 39

- epithelium which allows for expansion and stretch - found ONLY in the bladder

Question 40

how does ulceration occur?

Answer 40

when there is a break in continuity of epithelium

Question 41

what causes oral squamous cell carcinoma?

Answer 41

dysplastic epithelial cells proliferating in an uncontrollable manner, which destroy and invade adjacent tissues