8 Cell Surface Specialisation

Question 1

Goblet cells

Answer 1

Mucus secretions—> moistens and lubricates

They lack cilia on apical surface but have microvilli instead

Release mucins via exocytosis

H2O release increased by release of ions

Question 2

Cystic Fibrosis

Answer 2

Mutation in CTFR so chloride ion release deficiency
Affects tissues that have mucins and cilia.

For example:

Airways clogging up and getting infected as have thick sticky mucus. This obstructs breathing and damages lungs.
In the liver the small bile. Duct becomes blocked.
In the pancreas zymogen secretions not releases.
In small intestine they have thick non motile stools (requires surgery in infants, high mortality rate)
Reproductive tracts: normally infertile in males as thick mucus prevents semen transit.
In the skin: salty sweat, can sometimes see crystals on the skin.

Question 3

Clara cells (club-like cells)

Answer 3

Job is to protect epithelium
Don’t have basal bodies or cilia.
Found on the bronchioles.

Secrete uteroglobin.

Responsible for detoxifying harmful substances inhaled into lungs with cytochrome P450 enzymes on their SER.

Can also act as stem cells. Especially when tissue is damaged, can differentiate into ciliated cells.

Question 4

Microfold cells

THIS IS THE EPITHELIAL CELL THAT ISN’T ATTACHED TOTHE BASLA MEMBRANE

Answer 4

Only found in small intestine, close to lymphatic nodules.
Role is to trap pathogens and other molecules and present them to dendritic cells.
It has a folded extension that ‘samples’ the lumen by endocytosis.
Many pathogens exploit the as their portal of entry into the system.

Question 5

Stereocilia

Answer 5

In the inner ear. They are the mechanosensing organelle of hair cells which respond to fluid motion for hearing and balance.
Contain actin and myosin filaments.

Question 6

Smoking and the airway

Early stages

Answer 6

Normal mucus layer thickens
Cilia dies off
Ciliagenesis

Question 7

Smoking and airways

Chronic stage

Answer 7

Goblet and basal cells proliferate
Clara cells die
Carcinogens induce mutations and malignancy
Pneumocytes in the alveoli die

Question 8

Cell renewal rates

Answer 8

Trachea: 1-2 months
Alveoli: 8 days
Goblet cells: 10 days
Clara cells: never

Question 9

Common condition related to smoking:

Answer 9

Acute bronchitis: cough and mucus production < 3 months
Chronic bronchitis: for longer period ‘smokers cough’. Irreplaceable damage done.
Emphysema: permanent shortness of breath, damaged air sacs.
COPD: includes both emphysema and chronic bronchitis.
Asthma: wheezing, shortness of breath, chest tight and cough.