Integrating Cells Into Tissues

Question 1

In general terms, how are cells held together in a tissue?

Answer 1

Lateral domain and basal domain

Question 2

What is meant by lateral domain?

Answer 2

Cell attachment to each other, side to side

Question 3

What is meant by basal domain?

Answer 3

Cell attachment to the basement membrane

Question 4

In the lateral domain, what are the 3 types of cell junctions?

Answer 4

Tight junctions, desmosomes and gap junctions

Question 5

What is a tight junction?

Answer 5

In a tight junctions, adjacent cells are tightly connected due to fused plasmalemma which forms an impenetrable barrier. This forms a seal to prevent molecules passing between the cells.

Question 6

Where a tight junctions usually found?

Answer 6

Can be found in epithelium lining the intestine

Question 7

What are desmosomes?

Answer 7

Adjacent cells are firmly adhered to one another and the connections between them are strengthened by desmosomes. They are formed by proteins that interlock and connect cells

Question 8

Where are desmosomes usually found?

Answer 8

Desmosomes are found just under/next to tight junctions. They can be found in epithelial cells that need to withstand physical stress such as the skin

Question 9

What are gap junctions?

Answer 9

Gap junctions allow adjacent cells to communicate effectively. Proteins called connexons form channels between cells that allow ions and small molecules to move back and forth.

Question 10

Where are gap junctions usually found?

Answer 10

They can be found in cardiac muscle where cell communication is important.

Question 11

In which two ways do cells attach to the basement membrane?

Answer 11

Hemidesmosomes and focal adhesions

Question 12

What are hemidesmosomes?

Answer 12

Integrin is found in the extracellular space and attaches the cell to the basement membrane

Question 13

Where are hemidesmosomes usually found?

Answer 13

These are found in tissues subject to abrasion such as the skin and epithelium of the oral cavity

Question 14

What are focal adhesions?

Answer 14

These anchor intracellular actin filaments to the basement membrane. They consist of proteins including integrin (a transmembrane protein) and play a prominent role in cell movement.

Question 15

What are integrins?

Answer 15

Integrins are transmembrane proteins that attach the cell cytoskeleton to the extracellular matrix. They also sense whether adhesion has occurred.

Question 16

What are the 3 apical domains?

Answer 16

Microvilli, stereovilli and cilia

Question 17

What are microvilli and where are they found?

Answer 17

These are cytoplasmic processes that extend from the cell surface. They are found in the intestine and kidney tubule.

Question 18

What are stereovilli and where are they found?

Answer 18

These are long microvilli limited to epididymis and sensory hair cells of the ear.

Question 19

What are cilia and where are they found?

Answer 19

Cilia are motile cytoplasmic processes that beat in synchrony with rapid forward movement. They are found in the tracheobronchial tree and oviducts.

Question 20

What proteins are used by desmosomes?

Answer 20

Desmogleins - family of cadherins

Question 21

Name a disease that is caused by the formation of antibodies against desmosomes

Answer 21

Pemphigus vulgaris