OrganisationKey Facts
Key Facts: Respiratory System Structure
Part of Gas Exchange in Humans — GCSE Biology
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.
Topic position
Section 10 of 19
Practice
19 questions
Recall
23 flashcards
Key Facts: Respiratory System Structure
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%