Lecture 8- Cell Junctions/Epithelial Tissue

Question 1

What do gap junctions do?

Answer 1

Mediate cell to cell communication

Question 2

What is the purpose of the intercellular channel?

Answer 2

Permits direct cell-cell transfer of ions and small molecules

Question 3

Connexin make up connexon which form ______ _______

Answer 3

Connexin make connexon which form intracellular channels

Question 4

Gap junctions connect the _____ in adjacent ____

Answer 4

Cytoplasm
Cells

Question 5

Gap junctions can couple cells

Electrically
Metabolically
Electrically and metabolically
None of the above

Answer 5

Electrically and metabolically

Question 6

What permits tissue specific gap junctions?

Answer 6

Isoforms

Question 7

Different combinations of connexins create channels that differ in _______ and ______

Answer 7

Permeability and regulation

Question 8

pH, calcium levels, or signals (neurotransmitters) help mediate what in channels?

Answer 8

Regulation

Question 9

Turnover of connexons is rapid and occurs through what process?

Answer 9

Exocytosis

Question 10

What do tight junctions form?

Answer 10

Leak proof intercellular seal by the fusion of adjacent cell membranes

Question 11

What surface do tight junctions form near?

Answer 11

Apical surface

Question 12

What substances are permeable in tight junctions?

What allows permeability to vary?

Answer 12

Ions and small molecules

Type of tissue. Some molecules/ions are more permeable in certain tissues

Question 13

What is the major protein in tight junctions?

Answer 13

Claudin

Question 14

True or false: Claudin has many different isoforms

Answer 14

True

Question 15

What is the permeability of the seal in Claudin?

No permeability
Permeable
Selectively permeable
None of the above

Answer 15

Selectively permeable

Question 16

Dysregulation of claudin proteins can lead to _____ and _____ ____ _____

Answer 16

Cancers
Inflammatory bowel diseases

Question 17

Increased inflammation on a cell has what effect on claudin?

Answer 17

Claudin dysfunction and impaired barrier function

Question 18

When tight junctions are impaired, what happens with epidermal growth factors?

Answer 18

They go where they shouldn’t go and the influx contributes to tumorigenesis

Question 19

What substance helps recover epithelial claudin expression?

Answer 19

Probiotics

Question 20

What type of junction adhere cells to other cells or the extracellular matrix?

Answer 20

Anchoring junctions

Question 21

Adherens junction and desmosomes are formed ______

Answer 21

Laterally

Question 22

Hemidesmosomes and focal adhesion are formed ____

Answer 22

Basally (basal surface)

Question 23

Adherens junction, desmosomes, hemidesmosomes and focal adhesion are what types of junctions?

Answer 23

Anchoring junctions

Question 24

What is the main transmembrane protein for adherens junction and desmosomes?

Answer 24

Cadherins

Question 25

What is the main transmembrane protein for hemidesmosomes and focal adhesion?

Answer 25

Integrins

Question 26

What filaments do adherens junction and focal adhesions link with?

Answer 26

Actin

Question 27

What filaments do demosomes and hemidesmosomes link with?

Answer 27

Intermediate filaments

Question 28

Where are adherens junctions located in regards to tight junctions?

Answer 28

Below tight junctions

Question 29

What must need to form before a tight junction can assemble?

Answer 29

Adherens junctions

Question 30

What element does cadherin structures depend on?

Answer 30

Ca2+ ions

Question 31

Mutations that disrupt the production of E-cadherin are often found in what type of cells?

Answer 31

Cancer cells

Question 32

What happens when E-cadherin function is gone?

Answer 32

Loss of structure/anchoring proteins which leads to spreading/invasive transformation of cancer

Question 33

Since desmosomes play a critical role in tissues subjected to mechanical stress, what tissues may they come in contact with?

Answer 33

Myocaridum, bladder, and skin

Question 34

True or false: hemidesmosomes and focal adhesion aid in the interaction of a cell- extracellular matrix

Answer 34

True

Question 35

What is the main transmembrane protein for gap junctions?

Answer 35

Connexins

Question 36

What is the main transmembrane protein for tight junctions?

Answer 36

Claudins

Question 37

What are the four main functions of cell junctions? *Hint: think ASCC*

Answer 37

1. Attachment 2. Separation 3. Communication 4. Cell Polarity

Question 38

What is epithelial tissue?

Answer 38

Sheets of cells covering all surfaces of the body which are exposed to outside world Also lines the outside of organs

Question 39

What is the endothelium?

Answer 39

Lines the surface of the circulatory system but does not connect to the exterior of body

Question 40

What does the first name of the tissue type denote?

Answer 40

Number of layers Simple=one Stratified=more than one

Question 41

What does the second name of the tissue type denote?

Answer 41

Shape of the cells Squamous Cuboidal Columnar

Question 42

What is the function of simple squamous tissue?

Answer 42

-Regulates the passage of substances into tissue -Typically lines blood vessels and body cavities *Very thin layer*

Question 43

What is the function of simple cuboidal tissue?

Answer 43

-Secretion and absorption -Typically found in glandular (secreting) tissue

Question 44

What is the function of simple columnar tissue?

Answer 44

-Transportation and absorption -Contains apical cilia and microvilli -Usually lines stomach and intestines

Question 45

What is the function of stratified squamous tissue?

Answer 45

-Protection -Example: outer layer of skin

Question 46

What is the function of stratified cuboidal?

Answer 46

-Secretion -Found in excretory ducts of salivary and sweat glands

Question 47

What is the function of stratified columnar?

Answer 47

-Secretion -Found in the mucous membranes *Rare*

Question 48

Where is pseudo-stratified columnar tissue located?

Answer 48

Lines the upper respiratory tract and usually has a lot of cilia

Question 49

What type of structure does transitional epithelium tissue take on? Where is it located usually?

Answer 49

-Flattened structure when several layers are stretched -Lines most of urinary tract and allows bladder to expand

Question 50

Cardiac arrhythmia would be most likely associated with the malfunction of Desmosomes Adherens junctions Tight junctions Hemidesmosomes None of the above

Answer 50

None of the above

Question 51

Mutations in claudins will most likely disrupt the structure of Desmosomes Adherens junctions Tight junctions Hemidesmosomes Both a and b

Answer 51

Tight junctions

Question 52

Which of the following tissues has a protective function? Stratified Cuboidal Stratified squamous Simple squamous Stratified columnar Simple cuboidal Simple columnar

Answer 52

Stratified squamous