AQA AS Biology Unit 1 3.1.4 Lungs and Lung Disease

I made these revision notes using my class notes, the AQA AS Biology textbook and the specification.

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Revision: Unit 1 Biology and Disease 3.1.4 Lungs and Lung Disease
Lung Function
As you breathe in, air enters the trachea.
The trachea splits into two bronchi.
o One bronchus leading to each lung.
Each bronchus then branches off into smaller tubes called bronchioles.
The bronchioles end in small `air sacs' called alveoli.
The ribcage, intercostals muscles and diaphragm all work together to move air in and out.

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O2 diffuses out of the alveoli, across the alveolar epithelium and the capillary endothelium.
CO2 diffuses into the alveoli the blood, and is breathed out.
Diffusion of gases between the alveoli and the blood will be very rapid because:
o Red blood cells are slowed as they pass through pulmonary capillaries, allowing more time for diffusion.
o The distance between the alveolar air and the red blood cells is reduced as the red blood cells are flattened against
the capillary walls.…read more

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Pulmonary ventilation the volume of air taken into the lungs in one minute.
Tidal volume the volume of air in each breath.
Ventilation rate the number of breaths per minute.
Lung Disease
Pulmonary Tuberculosis (TB)
Causes and Symptoms
o TB is caused by the bacteria Mycobacterium tuberculosis or Mycobacterium bovis.
o Symptoms usually include;
Persistent cough, fatigue, weight loss due to loss of appetite, coughing up blood and mucus,
o Transmitted by droplet infection.…read more

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Airways become inflamed and irritated
o Usually due to an allergic reaction e.g. pollen and dust.
During an asthma attack, the smooth muscle lining the bronchioles contracts and a large amount of mucus is
Causes constriction of the airways, makes it difficult for the sufferer to breathe properly. Air flow in and out of
lungs is severely reduced, so less O2 enters the alveoli and therefore the blood.
o Wheezing, tight chest, shortness of breath.…read more



thank you ever so much! These are so useful

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