CF PROBLEMS:
• CF is caused by a faulty transport protein in the surface membranes of epithelial cells
• CF creates a sticky mucus layer that lines the tubes and ducts in the gas exchange, digestive and reproductive systems.
• The sticky mucus increases the chances of lung infection and makes gas exchange less efficient.
• microorganisms become trapped in the sticky mucus causing illness
• cilia cannot move the mucus because it is too sticky
• low levels of oxygen in the mucus so harmful bacteria can live in these conditions
• gasses such as oxygen cross the walls of the alveoli into the blood system by diffusion, the sticky mucus makes it harder for diffusion to take place The mucus on the surface of the epithelial cells is sticky because it contains less water than normal.
CF AND LUNGS
WITH EXCESS WATER:
• Na+ is actively pumped across the basal membrane
• Na+ diffuses through sodium channels in the apical membrane
• Cl- diffuses down electrical gradient
• water is drawn out of cells by osmosis due to the high salt concentration in the tissue fluid
• water is drawn out of the mucus by osmosis
WITH TOO LITTLE WATER:
• Cl- s pumped into the cell across the basal membrane
• Cl- diffuses through the open CFTR channels
• Na+ diffuses down the electrical gradient into the mucus
• elevated salt concentration in the mucus draws water out of the cell by osmosis
• water is drawn out of the cell by osmosis
CF AND THE DIGESTIVE SYSTEM
With CF: CTFR channel is absent or not functioning, and the Na+ channel is permanently open, water is continually
removed from the mucus by osmosis
• In a person with CF the pancreatic duct becomes blocked by sticky mucus, impairing the release of digestive enzymes.
• The lower concentration of enzymes within the small intestine reduces the rate of digestion.
• Because of this the food is not fully digested and not all the nutrients can be absorbed
• The pancreatic enzymes can also become trapped behind the mucus blocking the pancreatic duct.
• The enzymes damage the pancreas.
• Damage to the cell walls in the pancreas that produce insulin, insulin is involved in the control of blood sugar levels, a form of diabetes can be the result.
CF AND THE REPRODUCTIVE SYSTEM
FEMALES WITH CF:
• have a reduced chance of becoming pregnant because a mucus plug develops in the cervix this stops sperm from reaching the egg.
MALES WITH CF:
• commonly lack the vas deferens (sperm duct) on both sides which means sperm cannot leave the testes.
• When the vas deferens is present it can become blocked by a thick sticky mucus layer, which means fewer sperm are present in each ejaculate
TREATMENT’S
MEDICATION:
• Bronchodilators – inhaled using a nebulizer. the drugs relax the muscles in the airways opening them up.
• Antibiotics – used to kill or prevent growth of bacteria in the lungs
• DNAase enzymes – DNAase enzymes can be inhaled using a nebulizer. They break down the DNA, so the mucus is easier to clear from the lungs.
• Steroids – used to reduce inflammation of the lungs.
DIET:
eat high energy foods and double the quantity of protein compared to people without CF, and salt supplements.
DIGESTIVE ENZYME SUPPLEMENTS:
Taking these with food helps to complete the process of digestion.
PHYSIOTHERAPY:
Rhythmical tapping of the walls of the chest cavity can help loosen the mucus and improve the air flow into and out of the lungs.
HEART AND LUNG TRANSPLANT:
if the lungs become badly damaged the only option may be to replace the damaged lungs.
GENETIC TESTING:
The DNA is tested to see whether it contains the known base sequences for the most common mutations that cause cystic fibrosis.
How can genetic screening be used?
• to confirm a diagnosis
• to identify carriers
• for testing embryos – amniocentesis involves inserting a needle into the amniotic fluid to collect cells that have fallen of the placenta and fetus
• chorionic villus sampling – a small sample of placental tissue is removed, either through the wall of the abdomen or through the vagina.
• testing before implantation – when carrying out in vitro fertilization it is possible to test an embryo before it has implanted in the uterus. a cell can be removed from an embryo, the cells can then be analyzed and used to decide whether to place the embryo into the womb.
POSSIBLE CF TREATMENTS FOR THE FUTURE
In gene therapy the genotype and hence the phenotype of target cells is altered.
This is done by:
• inserting normal alleles of the gene into the target cells (by using either genetically modified virus to infect the target or using liposomes
• the normal form of the gene is transcribed and translated
• a functioning protein is produced in the target cells
HOW GENES ARE INSERTED USING VIRUSES:
• the DNA sequence that allows it to replicate is removed
• this is replaced with a normal allele of the desired gene
• when the virus infects the desired target, the viral DNA becomes incorporated into the patient’s own DNA
HOW GENES ARE INSERTED USING LIPOSOMES:
• copy of the normal allele is inserted into a loop of DNA (plasmid)
• the plasmid is then combining with liposomes
• the positively charged head groups of the phospholipids combine with the DNA
• the liposomes fuse with the epithelial cell membranes and carry the DNA to cells