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 2 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 2 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%