B5 - The Respiratory System and its Diseases Flashcards
The diagram of the Lung
Look at a picture and memorise
What is the difference between gaseous exchange and ventilation? ( humans )
Your lungs are your gaseous exchange surface. The many millions of air sacs (alveoli) in the lungs give a large surface area for oxygen to diffuse into your blood and for carbon dioxide to leave your blood and be breathed out. Breathing, or ventilation, is how you get the air in and out of your lungs.
Describe everything that happens during inspiration ( breathing in)
• Your intercostal muscles contract and raise your rib cage up and out.
• Your diaphragm flattens.
• These two things increase the volume inside your chest and lungs.
• The air pressure in your lungs is lower than outside.
• So air enters the lungs from outside. It passes along the trachea, bronchi, and bronchioles to the alveoli.
Describe everything that happens during expiration ( breathing out)
• Your intercostal muscles relax and your rib cage lowers.
• Your diaphragm domes upwards.
• These two things reduce the volume in your chest.
• The air pressure in your lungs is greater than outside. Your elastic alveoli also recoil (snap back) to normal size.
• So air is pushed out from your lungs to outside. However, some air stays – this is residual air. If it didn’t stay, your alveoli would close up.
What can spirometers measure?
• tidal volume – the volume of air you breathe in, in one breath
• vital capacity – the maximum volume of air you can breathe in, plus your tidal volume, plus the maximum volume of air you can breathe out after taking a big breath in
• lung capacity – your vital capacity plus your residual air.
What happens at the alveoli?
The alveoli form your gaseous exchange surface. They link your blood to the air. At the alveoli:
• Oxygen diffuses from the alveoli into the bloodstream.
• Carbon dioxide that has entered your blood at your body
tissues diffuses from your blood into the alveoli, to be breathed out.
Describe the structure of alveoli and how they are adapted to their purpose.
The alveoli are surrounded by blood capillaries. The walls of your alveoli are just one single layer of cells. The walls of your capillaries are also just one single layer of cells. So the oxygen and carbon dioxide do not have far to diffuse. Alveoli are adapted for efficient gaseous exchange because they
• are permeable • have thin walls
• have a large surface area • have a good blood supply.
How does the respiratory system protect itself?
There is a layer of cells lining the trachea and bronchi. Some of these cells have cilia and some secrete mucus.
• The mucus traps small particles and pathogens such as bacteria, viruses, and fungal spores.
• The cilia beat and waft the mucus up to the back of the throat.
• Once there it can be swallowed, and the stomach acid kills
the trapped pathogens. Or it can be removed by coughing or blowing your nose.
You also have special white blood cells, called macrophages, that squeeze out of capillaries and patrol the lung tissues. They ingest foreign particles and some pathogens.
What happens if the sweeping system doesn’t work?
The airways end in the lungs and go no further – they are a dead end. Any pathogens entering the lungs will cause infection unless they are trapped and wafted back up the airways, out of the lungs. If the cilia are not working properly, small particles and pathogens remain in the lungs and can cause disease.
What is the cause and symptoms of bronchitis?
Cause - Virus or bacteria, can also be triggered by breathing in smoke
Symptoms - Cough (often bringing up a yellow-grey mucus), sore throat, wheezing, blocked nose.
What is the cause and symptoms of asbestosis?
Cause - Asbestos bres trapped in the alveoli. This is an occupational disease. Some people have been exposed to the bres during their work.
Symptoms - In ammation and scarring of the alveoli, leading to dif culty breathing and reduced gaseous exchange. May lead to cancer.
What is the cause and symptoms of cystic fibrosis?
Cause - Genetic and inherited
Symptoms - Cells lining the airways are affected. Thick mucus is secreted. Cilia are not hydrated enough and cannot waft. Mucus with trapped pathogens builds up, and this leads to chest infections and reduces gaseous exchange. Lungs eventually become damaged.
What is the cause and symptoms of lung cancer?
Cause - Most commonly tar in tobacco smoke
Symptoms - Cells lining the bronchioles keep on dividing, forming a tumour. This reduces the surface area for gaseous exchange, and causes chest pain and a prolonged cough, with blood.
What is the cause and symptoms of asthma?
Cause - Inhaling pollen or other allergens, infection, cold air, hard exercise, or stress
Symptoms - Dif culty breathing, wheezing, tight chest. Can be treated with bronchodilator drugs taken via an inhaler.
(A*) Lining of the airways becomes inflamed, causing a build up of uid. The muscles in the bronchi contract. This makes the bronchi constrict (become narrower), restricting the airways.
