How cystic fibrosis affects the lungs

Symptoms: • Severe coughing - to remove excess mucus.• Breathlessness - shortage of oxygen increases tiredness and lack of

energy• Infections - as bacteria are trapped in mucus

Sticky mucus builds up in the airways, reducing flow of air into alveoli. Lungs gradually fill up with mucus, making them less effective for gas exchange.

How does cystic fibrosis affect the reproductive systems?

Men Women

Sperm duct is blocked and prevents movement of sperm

During the menstrual cycle the levels of mucus vary.

Can lack the sperm ducts

Women with CF have thick levels of mucus which can block the cervix so sperm cannot reach them.

How cystic fibrosis affects the digestive system:

Thick, sticky mucus blocks the pancreatic duct preventing enzymes from reaching the duodenum.

Food is not digested and absorbed sufferers fail to put on body mass and suffer malnutrition.

Trapped digestive enzymes damage the pancreatic cells affecting cells producing insulin resulting in diabetes.

What does the CFTR protein do?It helps control the viscosity (or stickiness) of mucus that lines the epithelial cells of the airways, digestive and reproductive systems

too runny: the mucus can flood the airways

mucus

cilia

epithelial cell

If the mucus in airways is…

too sticky: the cilia cannot beat and remove the mucus, which then clogs up airways

When there is excess water in the mucus

mucus

tissue fluid

CFTR channel closedNa+

channel open

pump

Na+

Na+

H2O

H2O

Cl-

apical membrane

basal membrane1

2

3

4

5

Water is drawn out of the mucus and it thickens

Cl-

H2O

When there is too little water in the mucus

mucus

tissue fluid

CFTR channel

open

Na+

channel closed

Na+Na+

H2O

H2O

Cl-

apical membrane

basal membrane

Cl-1

23

4

5

Water is drawn out of the mucus and it becomes less sticky

Na+

H2O

The CFTR somehow blocks the sodium channels

pump

With cystic fibrosis

mucus

tissue fluid

CFTRnon-

functionalNa+

channel open

Na+

H2O

H2O

Cl-

apical membrane

basal membrane

X

Water drawn out by osmosis

1

2 3

The mucus becomes very thick and sticky

Cl-

H2O

The CFTR protein cannot block the sodium channels so they are always open

Check your answers!

1. Na+ is actively pumped across the basal membrane (bottom part).

2. Na+ diffuses through sodium channels in apical membrane (top part).

3. Cl- diffuses down electrical gradient (basal end of cell becomes more positively charged due to Na+).

4. Water is drawn out of cells by osmosis due to high salt concentration in tissue fluid (basal end).

5. Water is drawn out of mucus by osmosis.

1. Cl- is pumped into the cell.

2. The CFTR channel is open so Cl- ions diffuse through to the mucus.

3. Na+ then diffuses down the electrical gradient (area of negative charge) into the mucus.

4. There is a high concentration of salt in the mucus so water leaves the cell and enters the mucus by osmosis.

5. Water from the basal end of the cell is drawn into the cell by osmosis.

Use your knowledge of functioning CFTR proteins to explain why CF patients cannot control their

mucus fluidity

mucus

tissue fluid

CFTRnon-

functionalNa+

channel open

Na+

H2O

H2O

Cl-

apical membrane

basal membrane

X

Water drawn out by osmosis

1

2 3

Cl-

H2O

The CFTR protein cannot block the sodium channels so they are always open