The structure and functions of the five main types of cell junctions

Question 1

list the all cell junctions

Answer 1

• tight junctions
• adhesion junctions
• desmosomes
• hemidesmosomes
• Gap junctions

Question 2

breifly describe the funtion of tight,adhering and gap junction.

Answer 2

• Tight junctions prevent movement of substances
• Adhering junctions maintain cellular position
• Gap junctions allow movement of substances

Question 3

what are tight junctions?

Answer 3

formed by the fusion of integral proteins of adjacent cells and prevent anything passing through the extra cellular space between them.

Question 4

give an example of where tight junctions are found

Answer 4

cells lining the digestive tract.

Question 5

what are adherent junctions?

Answer 5

• Plaque which attaches to membrane proteins and the microfilaments of the cytoskeleton
• Often form adhesion belts.

Question 6

why is adherent junctions important in peristalsis?

Answer 6

Resist separation in contractile activities such as peristalsis
holds the cells together

Question 7

what are Desmosomes and Hemidesmosomes

Answer 7

These are anchoring junctions held together by linker protein filaments called cadherins or integrins extending from button like thickenings called plaques.
Distributes tension and prevents tearing.

Question 8

give examples of where Desmosomes and Hemidesmosomes are most abundence in.

Answer 8

skin and heart muscle

Question 9

what are gap junctions ?

Answer 9

The adjacent cells are connected by hollow cylinders called connexons made of trans membrane proteins

Question 10

where are gap junctions found?

Answer 10

Found in electrically excitable tissues for synchronization

e.g. heart and smooth muscle