Topic 2- Genes And Health

Question 1

What do goblet cells do?

Answer 1

They line the tissue of the lungs and produce mucus which traps mucus and bacteria

Question 2

How is the regulation of mucus achieved by?

Answer 2

By the transport of Na+ and Cl- across the epithelial cells.

Question 3

What happens when there’s too much water in the mucus?

Answer 3

1. Carrier proteins in basal membranes pump Na+ out of the cells and into the tissue fluid. Na+ concentration in cells decrease -> creating concentration gradient.
2. Na+ diffuses by facilitated diffusion into cells from mucus through ENaCs in apical membranes.
3. Cl- diffuses down the electrical gradient into the tissue fluid. Solute concentration in tissue fluid increases.
4. Water leaves cells by osmosis, enters tissue fluid. Solute concentration in cells increase, water enters from mucus by osmosis.

Question 4

What happens when there is too little water in the mucus?

Answer 4

1. Cl- ions are actively transported from the tissue fluid to the cell through the basal membrane. Cl- ion concentration increases creating a concentration gradient which causes the CFTR protein Chanel to open in the apical membrane.
2. Cl- diffuses out of the cell into the mucus through the CFTR channel. The open CFTR channel blocks the ENaCs.
3. Cl - builds up in the mucus, creating an electrical gradient between the mucus and the tissue fluid. Na+ diffuses from tissue fluid into mucus down conc gradient.
4. Solute conc in mucus increases and so water leaves cell by osmosis into mucus which increases solute concentration in cell.
5. Water enters cell by osmosis from tissue fluid.

Question 5

What makes people with cystic fibrosis different?

Answer 5

The CFTR protein channel may be missing or not functioning properly which meant that there is too little water in the mucus.

Question 6

Explain the process in people with cystic fibrosis

Answer 6

1. The missing CFTR means that Cl- can’t be secreted across the apical membrane and also the ENacs can’t be closed.
2. Since the ENaCs are always open, Na+ is continuously moving into the cell by facilitated diffusion. This increases solute concentration in the cell and so water moves from the mucus into the cell.
3. Carrier proteins in the basal membranes continue pumping Na+ out of the cell and into the tissue fluid. Na+ concentration decreases in the cell which creates a gradient.
4. Cl- diffuses down the electrical gradient into the tissue fluid so the solute concentration in the tissue fluid increases.
5. Water leaves the cell and enters the tissue fluid. Solute conc in cell increases so water leaves mucus into the cell.

— mucus becomes more sticky.