Automatic Control Centre
The medulla oblongata in the brain stem automatically controls breathing rate:
- Primary trigger: COโ concentration in blood (not oxygen!)
- Chemoreceptors detect changes in blood pH (caused by COโ levels)
- High COโ โ more acidic blood โ increased breathing rate
- Low COโ โ less acidic blood โ decreased breathing rate
Factors Affecting Breathing Rate
Exercise: Increases COโ production โ faster breathing
Emotions: Stress, fear โ adrenaline โ faster breathing
Temperature: High fever โ increased metabolic rate โ faster breathing
Altitude: Low oxygen โ breathing rate increases (but slowly adapts)
This key facts covers Breathing Rate Control 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 7 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 are alveoli?
Tiny air sacs in the lungs where gas exchange takes place - oxygen enters the blood and carbon dioxide leaves
What is the trachea?
The main airway (windpipe) that carries air from the throat to the lungs, reinforced with cartilage rings