Test 1 - Lecture 4 (epithelium)

Question 1

What are the 6 functions of epithelial tissue?

Answer 1

1. secrete
2. excrete
3. absorb
4. transport
5. protect
6. receptor

Question 2

What is epithelioid tissue? What makes it different from epithelium, histologically?

Answer 2

Have same function as epithelium and look like them, but there is no true lumen or apical domain (common in endocrine and male reproductive tracts)

Question 3

Mucosa

Answer 3

lines cavities that connect with outside of body

Question 4

Serosa

Answer 4

lines closed cavities (touches body wall and other organs)

Question 5

Describe simple squamous epithelium.

Answer 5

1. single layer
2. width of cell > height of cell (flat)
3. Fx: transport, barrier

Question 6

What is mesothelium?

Answer 6

outer covering of organ

Question 7

What is endothelium?

Answer 7

epithelium that lines blood vessel

Question 8

Describe simple cuboidal epithelium.

Answer 8

1. single layer
2. width x depth x height equal (cube)
3. nucleus is generally in center of cell

Question 9

From what you can gather, what is the purpose of having a tissue with simple squamous vs. simple cuboidal/columnar?

Answer 9

Simple squamous just forms a barrier so it doesn’t need a lot of extra room for extra organelles. Simple cuboidal/columnar secret and absorb as well as provide a barrier, so need extra space for organelles and specialized structures

Question 10

Describe stratified squamous epithelium.

Answer 10

1. many layers
2. surface looks like true squamous
3. many mitotic cells shed at apical domain

Question 11

Why would a region have stratified squamous epithelium as opposed to another epithelium type?

Answer 11

Areas that go through high cell turnover & shed cells, but also provide protection (epidermis, oral cavity, esophagus, vagina during childbirth)

Question 12

Describe stratified cuboidal epithelium.

Answer 12

1. multiple layers (2-3)
2. Surface is true cuboidal layer

Question 13

Where are the only places you will find stratified cuboidal epithelium?

Answer 13

1. sweat gland ducts
2. large exocrine gland ducts
3. anorectal junction

Question 14

Describe stratified columnar epithelium.

Answer 14

multiple layers (apical tends to be true columnar & lower cuboidal)

Question 15

Where are the only places you with find stratified columnar epithelium?

Answer 15

1. large exocrine gland ducts
2. anorectal junction
3. eye

Question 16

Describe pseudostratified columnar epithelium.

Answer 16

1. appears stratified
2. all cells on basement membrane
3. not all cells reach apex

Question 17

How does pseudostratified columnar epithelium differ from stratified columnar epithelium?

Answer 17

all cells are on the basement membrane and is still technically a simple epithelium

Question 18

Describe transitional epithelium

Answer 18

1. multiple layer
2. top layer cuboidal if distended and squamous if collapsed
3. only in transition areas such as bladder (full/empty)

Question 19

Apical domain.

Answer 19

at free surface/lumen - apical modifications

Question 20

Lateral domain

Answer 20

communication with adjacent cells - cell-junctions

Question 21

Basal domain

Answer 21

anchors cells to connective tissue - basement membrane

Question 22

What are the 3 apical modifications?

Answer 22

1. microvilli
2. stereocilia
3. cilia

Question 23

Microvilli

Answer 23

actin filament core (also has myosin & villin) - aka brush border (kidneys) or striated border (small intestine)

Question 24

Sterocilia

Answer 24

long microvilli; also made of actin

Question 25

Cilia

Answer 25

made of microtubule bundles generally in 9+0 and 9+2 arrangement

Question 26

What are the 3 main categories of junctions between cells?

Answer 26

1. occluding junctions
2. anchoring junctions
3. communicating junctions

Question 27

Occluding junctions

Answer 27

impermeable tight junctions made of occluden and claudin

Question 28

Anchoring junctions

Answer 28

stabilizing junctions
zonula: interacts with actin
macula: interacts with intermediate filaments

Question 29

Communicating junctions

Answer 29

aka gap junctions
small molecules pass between cells through diffusion
made up of connexin proteins

Question 30

What is the basement membrane?

Answer 30

It is the place where the epithelium attaches to and connects and with the connective tissue

Question 31

What substance mostly comprises the basement membrane?

Answer 31

carbohydrates

Question 32

What are the two parts of the basement membrane?

Answer 32

1. lamina dense
2. lamina lucida

Question 33

Are the two parts of the basement the same in non-epithelial cells?

Answer 33

no epitheloid cells the external lamina is the basal lamina

Question 34

Describe the cell to extracellular matrix junctions of the basal domain

Answer 34

1. focal adhesions: anchor actin to basement membrane important for mechanosensitivity
2. hemidesmosomes: anchor intermediate filaments to basement membrane located in epithelium that encounter abrasive and shearing force (cornea, skin, oral cavity, esophagus)

Question 35

Compare the 3 types of exocrine gland secretion.

Answer 35

1. merocrine (small molecules)
2. apocrine (large molecules)
3. holocrine (cell ruptures & spills contents with vesicles out)

• all 3 secrete products onto a surface - through epithelial ducts/tubes connected to surface

Question 36

What is the difference between exocrine and endocrine glands?

Answer 36

Exocrine have duct system and endocrine do not (secrete into connective tissue where things such as hormones can enter bloodstream)

Question 37

How do the paracrine and autocrine signals differ from exocrine and endocrine?

Answer 37

Both paracrine & autocrine give localized effects while the others do not
- paracrine: diffuse through CT (don’t go into bloodstream)
- autocrine: cell secretes and then secretion binds to itself & changes function of cell