Airways (Air Pathway):
- Trachea: Main airway, reinforced with cartilage rings
- Bronchi: Branch from trachea into each lung
- Bronchioles: Smaller branches within lungs
- Alveoli: Microscopic air sacs for gas exchange
Breathing Muscles:
- Diaphragm: Main breathing muscle (dome-shaped)
- Intercostal muscles: Between ribs, help expand chest
- External intercostals: Contract during inspiration
- Internal intercostals: Contract during forced expiration
Gas Exchange Statistics:
- ~300 million alveoli per lung
- Total surface area: ~70 square meters
- Alveolar wall thickness: 0.5 micrometers
- Breathing rate at rest: 12-20 breaths/minute
Blood Gas Transport (overview):
- Oxygen carried mainly by haemoglobin in red blood cells
- Carbon dioxide transported in plasma and red blood cells
- Oxygen saturation in healthy lungs: 97-99%
This key facts covers Key Facts: Respiratory System Structure within Gas Exchange in Humans for GCSE Biology. Lung structure, alveoli adaptations, breathing mechanism, gas transport in blood, and effects of smoking It is section 10 of 19 in this topic. Use this key facts to connect the idea to the wider topic before moving on to questions and flashcards.
Practice questions for Gas Exchange in Humans
Which is the correct order of structures air passes through to reach the lungs?
Explain how the structure of alveoli is adapted for efficient gas exchange.
Quick recall flashcards
What is the trachea?
The main airway (windpipe) that carries air from the throat to the lungs, reinforced with cartilage rings
What are alveoli?
Tiny air sacs in the lungs where gas exchange takes place - oxygen enters the blood and carbon dioxide leaves