1. RESPIRATORY system Learning Objectives
To be able to describe how we breath.
To be able to explain how breathing changes during exercise.
Content
1.2.6
Composition of inhaled and exhaled air and the impact of physical activity and sport on this composition
1.2.7
Vital capacity and tidal volume, and change in tidal volume due to physical activity and sport, and the reasons that make the change in tidal volume necessary
1.2.8
Location of the main components of the respiratory system (lungs, bronchi, bronchioles, alveoli, diaphragm) and the role in movement of oxygen and carbon dioxide into and out of the body
1.2.9
Structure of alveoli to enable gas exchange and the process of gas exchange to meet the demands of varying intensities of exercise (aerobic and anaerobic)

2. Composition of Inhaled Air
Water vapour is also a component of the air we inhale and this can be affected by the weather. On rainy days, there will obviously be more water vapour in the air.

3. Composition of Respiratory System
You need to know the passage air takes when entering the body, up to the point it enters the circulatory system.
Air first enters our body by passing through the mouth or nasal passage. It is better to breathe in through the nose because:
The nose has a filter to remove dust particles.
It warms the air to match body temperature.
It moistens the air so that it arrives in the lungs saturated with water.
After initially entering our body the air then passes through the larynx, trachea, bronchi, bronchioles, and finally the alveoli.

4. Composition of Respiratory System
The alveoli are very important as it is here gaseous exchange takes place.
Gaseous exchange is when oxygen and carbon dioxide are swapped due to the pressure gradients at the site.
Pressure gradient is when two areas have contrasting amounts of either CO2 or O2 (high and low). When this occurs, the gas moves from the area of high pressure to the area of low pressure.
Regular endurance training will result in an increase in the number of alveoli present in the lungs and an increase in the number of capillaries available to exchange gases with them.
Having more alveoli and capillaries available for gaseous exchange will lead to greater oxygen uptake during exercise, which can be used to release energy.

5. Inspiration and Expiration
…or breathing in and breathing out as we would normally refer to them.

6. Inspiration and Expiration
Inspiration – Breathing In The intercostal muscles contract, pulling the rib cage up and out. The diaphragm contracts, pulling down and flattening in shape. The space in the chest cavity increases, allowing air to flow into the lungs.
Expiration – Breathing Out
The intercostal muscles relax, lowering the rib cage.
The diaphragm relaxes, pushing upwards and returning to a dome shape.
The space in the chest cavity decreases, forcing air out of the lungs.

7. Lung Volumes
The average adult human can hold about 6 litres of air in the lungs. Tidal Volume is the movement of air into or out of the lungs in one normal breath. Vital Capacity is the maximum amount of air that can be expired after a maximal inspiration.

8. Questions
Explain why we need gaseous exchange to take place at the lungs and working muscles. (2 marks) Define the term vital capacity. (1 mark) List in order the areas of the respiratory system air flows through before entering the blood stream. (1 mark)