Biology - 4 Organising Animals and Plants - 4.5 Breathing and Gas Exchange

Ventilation

movement of air in and out of the lungs

Where are your lungs found?

thorax

What protects the lungs?

ribcage and intercostal muscles

Intercostal muscles

muscles between the ribs

Adaptations of alveoli [5]:

- thin walls (short diffusion distance)
- moist surfaces for dissolving gases
- good blood supply (capillaries)
- steep gradient maintained by ventilation and movement of blood
- lots for large surface area

How does the pressure in the lungs change during inhalation? [6]

1. intercostal muscles contract
2. ribs move upwards and outwards
3. diaphtagm contracts and flattens
4. volume of chest increases
5. pressure inside chest decreases
6. air is drawn into the lungs

How does the pressure in the lungs change during exhalation? [6]

1. intercostal muscles relax
2. ribs move downwards and inwards
3. diaphragm relaxes and moves upwards
4. volume of chest decreases
5. pressure inside chest increases
6. air is forced out of the lungs

Journey of inhalation: [5]

- enters nose/mouth
- down trachea
- enters bronchi
- enters bronchioles
- enters alveoli