BRAINCAKERole of Alveoli in Gas Exchange
The rate of diffusion is proportional to the surface area and the diffusion gradient and inversely proportional to the diffusion distance.
Ventilation (inspiration) refreshes the lungs and brings in more oxygen into the lungs. Blood flow removes the oxygen that has diffused from the lungs into the capillary. This maintains the steep concentration gradient.
The walls of the capillaries and the walls of the alveoli are very thin. This ensures a short diffusion distance.
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Key terms in this lesson
- diffusion
- The net movement of molecules or ions from a region of higher concentration to a region of lower concentration, down a concentration gradient.
- ventilation
- The movement of air into and out of the lungs, which maintains a diffusion gradient across the gas exchange surface.
More in Exchange Surfaces and Breathing
- Mechanism of Breathing
- Inspiration
- Expiration
- Alveoli
- Asthma
- The First Breath
- Measuring Lung Capacity
- Lung Volume
All 24 lessons in Exchange Surfaces and Breathing · All OCR AS-level Biology topics