AS AQA Unit 1 Biology - Lungs

Alveoli- Contain collagen, elastic fibres and lined with epithelium. Elastic fibres allow them to stretch and fill with air and spring back to expel CO2.

Bronchi- Cartalidge gets reduced as it gets smaller. Produce musus and have cilia.

Trachea-  Supported by rings of cartalidge.

Rib Cage- Supports and protects the lungs.

Bronchioles- Branching sub-divisions of bronchi. Muscle controls the amount of air which goes into the alveoli.

Macrophages- Found in the alveoli and defend body by bacteria.

Blood Vessels- Warm incoming air.

Surfactant Cells- Cells of the alveoli that produce a phospholipid, release a rich secretion on the surface of the alveoli, minimizes friction.

Hairs- Trap and filter dust particles.

Ciliated Epithelial Cells- Have goblet cells which produce mucus to trap dust particles.

• Intercostal muscles relax.
• Ribs and Sternum move down and in.
• Diaphragm muscles relax.
• Diaphragm more up (domed shape).
• Thorax volume decreases.
• Gas pressure in the thorax increases.

• Intercostal muscles contract.
• Ribs and sturnum move up and out.
• Diaphragm muscles contract.
• Diaphragm move down (flattens)
• Thorax volume increases
• Gas pressure in the thorax decreases.

• Triggered by dust, smoke, pollution and cold air.
• Symptoms:- coughing, wheezing, shortness of breath.
• Smooth muscle contracts (spasms) which produces more mucus than normal, so airways become narrow, which in turn reduces ventilation and airflow is less efficient.

• Alveoli walls are damaged and replaced by connective tissue.
• Permanently stretches the elastin- does not force the air out of the alveoli. 
• Surface area of alveoli is reduced.
• Symptoms:- chronic cough, shortness of breath, blue colouration to skin due to lack of oxygen.
• Caused by smoking and pollution.