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Digestive system

The organ system in the body which breaks down large insoluble food molecules into small soluble molecules which can be used by the body

Cystic fibrosis

A genetic disease caused by a defective, recessive gene. It is characterised by the production of thick, sticky mucous in the lungs and pancreas which cause respiratory and digestive problems.

Tuberculosis

A communicable disease caused by bacteria. It affects millions of people around the world and can be cured by antibiotics, but increasingly the pathogenic bacteria are becoming resistant to the most widely used antibiotics.

 

Spinal cord

Part of the central nervous system made up of the main nerves which run up and down the body and the relay nerves involved in reflex actions, encased in the vertebrae for protection.

Antibiotic

Medicine that acts against bacterial infections. Penicillin is an example of an antibiotic.

Influenza

A viral infection of the breathing system which attacks the lungs and can be fatal

Virus

The smallest of living organisms. Viruses are made up of a ball of protein that contains a small amount of the virus DNA. They can only reproduce after they have infected a host cell

Polio

Viral disease causing paralysis which has been eradicated from most countries in the world by a vaccination programme

Conditions affecting the lungs

Common problems affecting the breathing system include asthma and smoking related diseases. These are not the only problems which affect various parts of the breathing system. Some of the others include:

  • Cystic fibrosis (CF) is a genetic condition which affects the lungs as well as other parts of the body such as the digestive system and the reproductive system. In CF the body makes very thick, sticky mucus. The cilia of the breathing system cannot move this mucus away from the lungs and so the lungs become very congested. People affected by CF are also likely to get infections in their airways and lungs.

    At the moment CF cannot be cured. However people who are affected use a combination of physiotherapy to get rid of the mucus from their lungs, exercise to keep them fit and make their lungs as big and effective as possible and medicines to keep them as fit and well as possible. The medicines used to treat the symptoms of CF include bronchodilators to open the airways and antibiotics to treat infections. It takes many different drugs to help people with cystic fibrosis live active lives.
  • If viruses get past the cilia and the mucus of the airways, they can infect the breathing system and cause diseases eg the common cold and influenza. Colds are not usually serious unless the person infected is already very unwell. However influenza ('flu) affects the nose, throat and lungs and can be very serious or even fatal. It causes damage to the lungs and makes them more vulnerable to further infections by bacteria. There are some antiviral medicines which reduce the length of the illness but generally there is little treatment for viral lung diseases.

Flu vaccines protect people against the most common flu viruses. (Photo credit: Douglas Jordan, M.A.)

Flu vaccines protect people against the most common flu viruses. (Photo credit: Douglas Jordan, M.A.)

  • There are a number of different bacterial diseases which affect the breathing system. These include bronchitis, pneumonia and tuberculosis (TB). In the past bacterial diseases of the breathing system were often fatal. Now most of them can be cured using antibiotics, medicines which kill bacteria or stop them growing in the body.

Supporting breathing

Sometimes people struggle to breathe. There are a number of different reasons for this. They include:

  • narrowing of the tubes leading to the lungs eg in asthma and bronchitis
  • the breakdown of the structure of the alveoli eg emphysema
  • paralysis of the muscles which move the ribs and the diaphragm – usually as a result of an accident or a disease

Scientists have developed some artificial aids to help people who have problems breathing.

There are two basic methods:

  • External negative pressure ventilators lower the pressure in a sealed unit around the chest. Air is pumped out of the unit, forming a vacuum, so the chest wall of the patient moves up, increasing the volume of the chest and decreasing the pressure inside the lungs. As a result air is forced into the lungs by atmospheric pressure, just like normal breathing. The pump switches off and air moves back into the chamber. This increases the pressure on the chest, so air is forced out of the lungs. The original external negative- pressure ventilators were commonly known as 'iron lungs'. They encased the whole patient apart from their head. They were used to keep people alive when they were paralysed as a result of diseases such as polio or from accidents which damaged the spinal cord.

    The modern version is a 'shell' which fits just around the chest so it is much easier for the patient to use.
An iron lung in use on a patient with polio in the 1960s

An iron lung in use on a patient with polio in the 1960s

However negative pressure ventilator systems have largely been overtaken now by positive pressure systems.

  • External positive pressure ventilation systems range from simple bags held over the face and squeezed by doctors and nurses in an emergency, to machines which can keep people who are paralysed alive for years. A positive pressure system forces a measured unit of air into the lungs under pressure, rather like blowing up a balloon. Once the lungs are inflated, the pressure stops and the ribs move down, forcing the air out of the lungs again. Patients can use the equipment in a normal home and even move about. The systems can be linked to a computer which makes even easier for patients to control their own breathing. Positive pressure ventilation systems save lives in emergency situations every day.