Oxygen Transport
- Majority bound to haemoglobin in red blood cells as oxyhaemoglobin (HbOโ)
- Small amount dissolved directly in blood plasma
- Each haemoglobin molecule can carry 4 oxygen molecules
- Oxygen binding is reversible: picks up Oโ in lungs, releases in tissues
- Oxygen saturation: percentage of haemoglobin carrying oxygen (normally 97-99%)
Carbon Dioxide Transport
- Most COโ is transported dissolved in plasma or as hydrogen carbonate ions
- A smaller amount is bound to haemoglobin
- COโ reacts with water inside red blood cells to form carbonic acid, which dissociates to release hydrogen carbonate ions into plasma
- Process is reversed in the lungs to release COโ for exhalation
This deep dive covers Gas Transport in Blood 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 6 of 19 in this topic. Use this deep dive 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