epithelia II A

Question 1

Apical surface modifications

Answer 1

1. microvilli

2. cilia

Question 2

Microvilli: These are extremely long, actin-filled microvilli, and are not related to cilia. In the ear, stereocilia function in the reception of sound

Answer 2

Cell surface extensions (protrusions) that contain actin bundles connected to cytoskeletal elements in the cell interior.

Question 3

Microvilli function:

Answer 3

to increase surface area, which greatly increases the rate/efficiency of membrane transport and secretion.

Question 4

Microvilli size

Answer 4

size and abundance of microvilli varies with cell type

Question 5

stereocillia are

Answer 5

These are extremely long, actin-filled microvilli, and are not related to cilia.

Question 6

Stereocilia are found

Answer 6

in the epididymis and in the sensory cells in the ear

Question 7

In the ear, stereocilia function in the

Answer 7

reception of sound.

Question 8

cilia are

Answer 8

Microtubule-containing extensions (protrusions)

Question 9

three kinds of cilia:

Answer 9

1. primary cilia
2. motile cilia
3. sensory cilia

Question 10

A primary cilium is a

Answer 10

single (one/cell) non-motile microtubule-based extension found on many different epithelial cell types.

Question 11

primary cilia function

Answer 11

organize and promote signal transduction systems (receptors and effectors) that control epithelial cell division, fate (differentiated state), and function

Question 12

motile cilia are

Answer 12

related microtubule extensions that move, and are found only on specific epithelial cell types;

Question 13

motile cilia function

Answer 13

these cilia wave like a boat oar to move mucous and other materials along passageways.

Question 14

motile cilia are found:

Answer 14

in epithelia of the respiratory tract (to move junk and mucous out of the airways), and in the oviduct (to assist in moving ova towards the uterus).

Question 15

sensory cilia function in

Answer 15

sensory reception (e.g. in vestibular hair cells of the ear).

Question 16

sensory cilia are

Answer 16

specific variations of primary cilia, specialized to house sensory (touch, taste) systems that are connected to the central nervous system.

high specialized, non-motile

Question 17

sensory cilia mutation result in

Answer 17

Mutations in proteins common to cilia or their support structures result in a large set of diseases called ciliopathies.

Question 18

ciliopathies are mutations in

Answer 18

sensory cilia mutation

Question 19

Basolateral surface modifications:

Answer 19

infolds and outfolds of the basolateral membrane are also found in many epithelial cells, though they seem to lack the structural organization of the apical microvilli and cilia.
These folds increase surface area and are likely to be seen in cells that transport heavily to or from their basolateral surface

Question 20

A basal lamina is a

Answer 20

1. thin sheet of extracellular material that underlies the basal surface of each epithelial tissue.
2. surround many other cell and tissue types as well; including the endothelium of blood vessels, muscle and nerve tissue.

Question 21

Basal laminae are formed by a ______.

Answer 21

special type of network-forming collagen, a fibrous protein.

This type of collagen forms sheets of thin fibers that are interwoven with a variety of other extracellular glycoproteins.

Question 22

What is the most common collagen to basal lamina?

Answer 22

Network-forming collagen (especially “type IV”) and some other glycoproteins including laminins and entactin

Question 23

It is thought that most of the basal lamina components are synthesized and secreted by ______

Answer 23

epithelial cells.

Question 24

Some extracellular components of the connective tissue (made by fibroblasts) function to:

Answer 24

bind to and possibly organize elements in the basal lamina.

Question 25

Basal laminae have several important functions:

Answer 25

1. They mediate attachment of epithelia to the underlying connective tissue. 2. Basal laminae often contribute to selective filtration of substances diffusing to or from the epithelia. 3. They are necessary for the establishment and maintenance of epithelial cell polarity. 4. They can serve as specific “highways” for the migration of cells through connective tissue. 5. They provide a barrier to movement of invading microbes or cancerous cell into other tissues. 6. They control the gene expression of cells to affect their proliferation or development. 7. They control the development, morphogenesis, and organization of epithelial cells, providing a sort of “tissue scaffolding” function. Thus, they are critical to the repair of epithelial tissue following damage by injury or disease.

Question 26

Basal laminae both separate ________, and attach ______.

Answer 26

epithelial cells from the underlying connective tissue, epithelial cells to the extracellular matrix of the connective tissue

Question 27

Epithelial cells directly connect to basal laminae by attachment of _____

Answer 27

hemidesmosomes and focal adhesions on the basal surface of the epithelial cell to components of the basal lamina.

Question 28

The key class of proteins that form these hemidesmosomes and focal adhesions are the ____

Answer 28

integrins (distinct proteins from the cadherins that mediate cell-cell linkage).

Question 29

Specific integrins of hemidesmosomes connect to _____

Answer 29

intermediate filaments in the epithelial cell and provide strength to the epithelial-connective tissue attachment.

Question 30

Different integrins of focal adhesions connect to _____

Answer 30

actin filaments inside the epithelial cell.

Question 31

Focal adhesions regulate

Answer 31

1. epithelial polarity

Question 32

Focal adhesions function through ____

Answer 32

signaling mechanisms and are particularly important during re-establishment of an epithelium following injury or disease, or during the normal process of cell replacement (turn-over)