IGCSE Chapter 03 Breathing & Gas Exchange

Define ventilation.

The movement of air into and out of the lungs.

Describe how air is taken into the lungs.

Intercostal muscles contract.

Diaphragm contracts.

Ribs move up and out.

Thorax volume increases.

Thorax pressure decreases.

Air moves in down a pressure gradient.

Explain the effect of emphysema on gas exchange in the lungs.

Reduced surface area of alveoli.

Therefore rate of diffusion of oxygen is reduced.

Therefore less oxygen absorbed.

Explain why breathing rate increases during exercise.

To increase the intake of air.

To allow more oxygen to diffuse across the alveoli into the blood.

For more aerobic respiration.

To release more energy for muscle contraction.

Gas exchange in the lungs occurs by what process?

Diffusion.

How do cells in the trachea protect the lungs?

Goblet cells secrete mucus.

The mucus traps bacteria and dust.

Ciliated cells waft the mucus and particles up to the throat (where swallowed).

How does carbon monoxide affect humans?

Binds with haemoglobin.

To form carboxyhaemoglobin.

Less oxyhaemoglobin formed.

State three adaptations of alveoli.

Large surface area because many of them.

Wall of the alveoli is thin for rapid diffusion.

Dense network of capillaries to take oxygen away/bring CO₂.

State three lung diseases that can result from smoking.

Bronchitis.

Emphysema.

Lung cancer.

What effect does tar have on the lining of the trachea?

Cilia are paralysed and do not waft mucus to back of throat.

Goblet cells produce more mucus.

What factors affect the rate of diffusion of a gas such as oxygen or carbon dioxide.

Surface area.

Concentration gradient.

Diffusion distance.

What forms when carbon monoxide binds to haemoglobin?

Carboxyhaemoglobin.

What is smoker's cough?

Tar in cigarettes causes goblet cells to produce more mucus and the cilia are paralysed.

So mucus accumulates.

Coughing therefore moves the mucus to the back of the throat.

What is the function of cartilage in the trachea?

To keep the trachea open during inspiration.

What is the function of the pleural fluid?

To lubricate the movement of the lungs against the chest wall during breathing.

Which muscles contract when breathing in?

Intercostal muscles and diaphragm.