PINAR OZBILGEHAN

BIOLOGY 2ND SEMESTER 1ST ASSIGNMENT

To the attention of Richard Llopis Garcia

City of Bath College

The most common major genetic disease in Britain

• Symptoms• Treatments

• PINAR OZBILGEHAN

CYSTIC FIBROSIS

What is cystic fibrosis?Cystic fibrosis is a defect in a plasma membrane protein called CFTR (cystic fibrosis transmembrane conductance regulator) that normally regulates passage of Cl– ions into and out of the body’s cells.

CFTR does not function properly in cystic fibrosis patients

It causes severe respiratory and digestive problems as well as salty sweat and often infertility.

The chlorine transport systems of exocrine glands , including the mucus-secreting glands of the airways of the lungs,the gut and the reproductive system and sweat glands, do not function properly .

As a result thick sticky mucus and very salty sweat are formed.

It is the thick mucus which causes most of the symptoms.

Cystic fibrosis a recessive autosomal genetic disease

which affects about 1 in 2500 babies born to white Europeans and 70,000 children and young adults worldwide.

Question: What is the chance of two carriers of cystic fibrosis having a child with cystic fibrosis?

Punnett square shows that two carriers have 1 in 4 chance of having a baby with cystic fibrosis.

Identifying carriers A sample of blood or some cells from the

inside of the mouth, can be used to carry out a simple test which identifies the allele.

All newborn babies are tested for several genetic diseases. In most cases, early treatment can avoid serious problems later on.

Why is CFTR protein important?

This complex process keeps the mucus produced by the epithelium lining your airways very runny. This helps your body prevent infection and also keeps the airways from getting blocked.

Chloride ions in tissue fluid are pumped into epithelial cells lining the airways by active transport by chloride pumps

Concentration of chloride ions inside the epithelial cells increases

Concentration gradient between the cell contents and the mucus on surface of cells increases.

The chloride ions move out of cells by simple diffusion through CFTR channel proteins which are open in the presence of ATP

CFTR channel proteins inhibits the passage of Na ions into the cell. Chloride ions have a negative charge , higher concentration of chloride in mucus attract positive sodium ions into the mucus

Therefore the concentration of Na ⁺and Cl ions in the fluid ⁻lining airways is higher.

Water diffuses out of epithelial cells by osmosis mixes with mucus and keeps it runny

Why is it important to keep mucus runny?

1. Runny mucus keeps the narrow ducts and tubes open.

Enzymes can pass from the pancreas into your gut. Sex cells can move in the reproductive system. The blockage of airways, pancreatic duct and

fallopian tube is prevented.

2. It helps your body prevent infection. The air you breathe in carries lots of tiny particles

which could block the alveoli . It also carries pathogens and so the respiratory

system provides a potential route inside the body where they can cause infection.

If the mucus is runny, it is easily moved up the airways by cilia that sweep upwards to the back of your throat.

Here the majority of mucus is swallowed without you even noticing it.

The acid in your stomach and your digestive enzymes digest mucus and everything carried with it.

In this way infection is prevented.

Your respiratory system produces lots of mucus which lines your airways and traps these tiny particles and pathogens.

Airway epithelium affected by cystic fibrosis

Symptoms of Cystic Fibrosis

Cystic fibrosis causes:

1. Respiratory problems

2. Digestive problems

3. Salty sweat

4. Infertility

The respiratory systemThe thick sticky mucus builds up in the tiny airways of the lungs and cannot be moved along and out of the system by the cilia.

1. Flow of air into the alveoli is reduced.

2. Without treatment the lungs gradually fill up with mucus, making them less effective for gaseous exchange.

Pathogens trapped in the mucus cannot be moved out of the respiratory system.

This provides the bacteria with ideal conditions in which to grow.

How does this affect a person with CF?

1. Affected individuals often have severe coughing fits as their body attempts to get rid of mucus.

2. They feel breathless and are often short of oxygen, making them feel tired and lacking in energy.

Scan of human lungs

These lungs are clear and healthy.

These lungs belong to a patient with cystic fibrosis.

Thin mucus is produced by the cells lining this tube. Also in the gut mucus is secreted in order to protect the delicate lining from damage by digestive enzymes and to act as a lubricant.

The enzymes pass from the pancreas into your duodenum along a tube known as the pancreatic duct.

Digestive enzymes made by glands in the lining of your gut and by pancreas are important for digestion of food..

Digested molecules are absorbed into your blood through the lining of duodenum which is covered in finger-like projections called villi that provide a large surface area for absorption.

The mucus of a person affected by CF is thick and sticky.

a)This often blocks the pancreatic duct.

Enzymes do not reach duodenum.

b) A barrier is formed between the contents of the gut and the lining of the intestine and clogs up the villi .

Surface area for absorption is reduced.

How does this affect a patient?1. Food cannot be digested properly and even if the

food is digested it can not be absorbed.Therefore the person does not get enough nutrients from the food and struggles to maintain their body mass.

2. The digestive enzymes trapped in the pancreas may start to digest and damage the cells of pancreas. If they are the cells which make the hormone insulin. The person may end up with diabetes.

The Reproductive System

uterus

ovaryendometrium

myometrium

cervix

Fallopian tube

The Female Reproductive System

The thick mucus can block the cervix so sperms cannot reach eggs.

It can also block fallopian tubes making fertilisation even less likely.

In women mucus in the reproductive system normally changes through the menstrual cycle. Mucus is thinner when a woman is fertile.

Women with cystic fibrosis usually produce fertile eggs.

epididymis

testis

Carries the sperm out from the testis into semen

may be absent if present may be partially or completely blocked by thick mucus so reduced number of sperm can leave the testis

A sample of normal semen contains vast numbers of sperm

A man affected by cystic fibrosis may produce only few or none if the tubes connecting the testes to the rest of the reproductive system is absent

The Sweat Glands Sweat is mainly salty water produced in sweat glands.

In sweat glands chloride pump works in the opposite direction to that in the mucus-producing glands.

Normally as sweat passes along the duct of a sweat gland salt(sodium chloride) is reabsorbed as a result of CFTR protein moving chloride ions into the cell.

Sodium ions follow along a concentraion gradient.

This reabsorption prevents you losing too much salt in sweat. Without CFTR proteins, chloride ions remain in the sweat and so the sodium ions.

People with cystic fibrosis have sweat that is more concentrated and salty than normal.

How does this affect the patient?

The loss of sodium and chloride ions causes health problems linked to the balance of ions in the body.

Levels of sodium and chloride ions are important for the proper functioning of many body systems,including :

nervous system and the heart.

If too much salt is lost in the sweat,the concentration of the body fluids changes which can affect the heart.

Life expectancy for CF was 10 years in 1962

And it was raised to 37 years in 2006

The aim is to make CF a controlled disease like asthma.. Now there is no cure.

The treatments available have improved enormously in recent years

The average life expectancy for affected people is increasing all the time.

Treatments Current treatments aim to reduce symptoms and allow

body systems to work as effectively as possible.

In the UK most people with CF will be looked after by a team of health professionals including doctors,nurses,physiotherapist,dieticians and others.

There is a range of treatments that tackle different symptoms.

Treatments to improve health and life expectancy

1. Physiotheraphy

2. Diet and enzymes

3. Drug theraphies

4. Transplant surgery

5. Infertility Treatments

1.PhysiotherapyVery important for removing as much of the thick sticky mucus from the lungs as possible.

Removing mucus through physiotherapy improves breathing and reduces the risk of lung infections taking hold.

This is usually done a couple of times a day but it varies according to patient and patent’s health any particular time.

There are devices which change the pressure in the airways and help people to clear their mucus without using more vigorous physiotheraphy.

1. Flutter

2. The positive expiratory pressure (PEP) valve

3. ThAIRapy bronchial drainage system

What people with cystic fibrosis need to do in order to overcome this problem of digestion and absorption of food?

1. They need to take enzymes when they have a meal to replace the missing pancreatic enzymes, so more of the food can be digested.

2. They need to eat a carefully balanced diet, and also to eat more than other people to make up for what they cannot digest. They need more high-energy foods.

2. Diet and Enzymes

3.Drug Theraphies Most people in the UK who have cystic fibrosis take a

cocktail of medicines to improve their health and protect them against the symptoms of the disease

These drugs include: a. Antibiotics b.Vaccines c. Mucolytics d. Asthma drugs e. DNAase enzymes f. Insulin

a. Antibiotics destroy many of the bacteria that could potentially cause life-threatening lung infections.

It can be difficult getting antibiotics to the tissue where they are needed, so AEROSOLS(inhalers) are used to breathe them deep into your lungs

b. Vaccines : CF patients also need a ‘flu vaccine every year to protect them against the most common forms of flu virus.

A vaccine against pneumonia is important too,since prevention is better than cure.

c. Mucolytics: These are drugs to make the mucus more runny and so easier to move.

d. Asthma drugs eg salbutamol and steroids- these are used to open the airways and to reduce the inflammation in the lungs.

e. DNAase enzymes make the mucus thinner and easier to cough up

f. Insulin- If problems with the pancreas lead to diabetes, insulin will need to be given regularly to control the blood sugar concentration.

4. Transplant Surgery In some cases the damage that cystic fibrosis causes to

lungs is so severe that the lungs cannot function properly. The heart may also be affected.

The ONLY SOLUTION: A lung, or heart and lung,transplant.

The rest of the body will still have the other problems associated with the disease.

What is the problem with a transplant surgery?

The patient’s body may react against the new tissue and reject it

After a transplant the person has to take IMMUNOSUPPRESSANT drugs for the rest of their life, to prevent their body reacting against the new tissue and rejecting it.

This suppresses the immune system,making it harder to fight infections

However, people with CF who have lung transplants usually do very well.

5.Infertility TreatmentsThe main steps in the process of in vitro fertilisation

There is no cure Aim is to remove all he symptoms by gene therapy . Hope for gene therapy:

1.The hope for gene therapy is that people will not need treatment after the initial medication.

2. Their quality of life and life expectancy will be much improved with no respiratory complications.

3. There would be a big financial saving without lifelong treatment.

The Journey of the Cystic Fibrosis Gene: An Educational Video

You can watch on youtube

REFERENCES1. Fullick, A. ,2008, Edexcel AS Biology Student’s

Book, Edinburgh Gate Harlow, Essex:Pearson Education

2. www.biol.sc.edu

3. www.patient.co.uk

4. http://www.amicusvisualsolutions.com/cgi-bin/reference.cgi?topic=0711112_FemaleReproductiveSystem

5. The Journey of the Cystic Fibrosis Gene: An Educational Video on youtube

Thanks for listening