Integrating Cells Into Tissues:

Question 1

What is the function of a tight junction?

Answer 1

Seals neighbouring cells together in an epithelial sheet to prevent leakage of molecules between them.

Question 2

What is the function of desmosomes?

Answer 2

Joins the intermediate filaments in one cell to those in a neighbour. This allows resistance to stretching and twisting due to interlocking proteins.

Question 3

What are gap junctions?

Answer 3

Connexon proteins that run between cells and form a channel between them. Allows substances to pass between cells e.g. ions.

Question 4

What is the basement membrane?

Answer 4

Thick protein - polysaccharide membrane which separates the epithelium from the underlying connective tissue and acts as an anchor for the epithelial cells.

Question 5

What do adherens junctions do?

Answer 5

Join an actin bundle in one cell to a similar bundle in a neighbouring cell.

Question 6

What do hemidesmosomes do?

Answer 6

Anchor intermedite filments in a cell to the basal lamina.

Question 7

What do focal adhesions do?

Answer 7

Anchor actin filaments in a cell to the basal lamina.

Question 8

What is the mucosal membrane?

Answer 8

A structure that lines all the moist hollow internal organs of the body, which secretes mucus.

Question 9

What is the function of the mucosal membrane?

Answer 9

• Stop pathogens and dirt from entering the body.
• Prevent bodily tissues from becoming dehydrated.
• Lubricate the surface.

Question 10

What does mucus contain?

Answer 10

Mucins (protein), electrolytes, immunoglobulins and water.

Question 11

Give 3 examples of where you would find the mucosal membrane:

Answer 11

• GI tract
• Urinary tract
• Respiratory tract

Question 12

What are the layers of the GI tract?

Answer 12

• mucosa
• submucosa ( smooth muscle layer)
• muscularis externa (smooth muscle layer)
• serosa (connective tissue layer)

Question 13

What is the function of the mucosa in the GI tract?

Answer 13

• To absorb substances from the lumen.
• Prevent ingress of pathogens.
• Move contents and expel waste.

Question 14

What is the special name given to epithelium found in the urinary tract?

Answer 14

Urothelium

Question 15

What is the function of the mucosal membrane in the urinary tract?

Answer 15

• Absorption of essential nutrients in the kidney.
• Prevention of pathogen entry.
• Removal of waste products.

Question 16

What do the conducting portions and respiratory portions of the respiratory tract consist of?

Answer 16

• Conducting portions = nasal cavity to bronchioles.

- Respiratory portions = respiratory bronchioles to alveoli.

Question 17

Describe the structure of the trachea and primary bronchi:

Answer 17

• mucosa (several cells deep + surface is covered in cilia)
• submucosa (connective tissue layer)
• C - shaped hyaline cartilage

Question 18

Describe the structure of the secondary and tertiary bronchi:

Answer 18

• similar to primary bronchi expect cartilage is no longer present as full circle of rings.

Question 19

Compare connective tissue with epithelial tissue:

Answer 19

• CT has sparsely distributed cells, ET has tightly bound together cells.
• CT has a plentiful extracellular matrix, absent in ET apart from basal lamina.
• CT matrix bears most of the mechanical stress, in ET it is the cells that bear most of the mechanical stress.

Question 20

What is the structure of connective tissue?

Answer 20

3 components:

• cells
• fibres
• ground substance

Question 21

What are the functions of connective tissue?

Answer 21

• binding and support (holding skin together)
• protecting (e.g. bone protecting vital organs)
• insulating (fat)
• transporting substances within the body (blood and interstitium)
• storing reserve fuel and cells ( bone marrow and fat tissue).