Lung function
- Created by: Rachh
- Created on: 07-01-13 13:13
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- The lungs
- Structure
- Air enters the trachea.
- The trachea splits into two bronchi.
- Each bronchus branches off into smaller tubes called bronchioles.
- The bronchioles end in small air sacs called alveoli, where gas exchange takes place.
- Each bronchus branches off into smaller tubes called bronchioles.
- The trachea splits into two bronchi.
- Air enters the trachea.
- Ventilation
- Inspiration
- The intercostal and diaphragm muscles contract.
- This causes the ribcage to move upwards and outwards and the diaphragm to flatten, increasing the volume of the thorax.
- As the volume of the thorax increases, the lung pressure decreases.
- This causes air to flow into the lungs.
- As the volume of the thorax increases, the lung pressure decreases.
- This causes the ribcage to move upwards and outwards and the diaphragm to flatten, increasing the volume of the thorax.
- It is an active process - it requires energy.
- The intercostal and diaphragm muscles contract.
- Expiration
- The intercostal and diaphragm muscles relax.
- The ribcage moves downwards and inwards and the diaphragm becomes curved again.
- The thorax volume decreases, causing the lung pressure to increase.
- Air is forced out of the lungs.
- The thorax volume decreases, causing the lung pressure to increase.
- The ribcage moves downwards and inwards and the diaphragm becomes curved again.
- It is a passive process - it doesn't require energy.
- The intercostal and diaphragm muscles relax.
- Inspiration
- Alveoli and gas exchange
- Factors affecting the rate of diffusion
- A thin exchange surface (short diffusion pathway)
- A large surface area - lots of very small alveoli means there's a large surface area for gas exchange.
- A steep concentration gradient of oxygen and Carbon dioxide.
- Alveoli structure
- Each alveolus is made from a single layer of thin, flat cells called the alveolar epithelium.
- The walls of the capillaries are made from capillary endothelium.
- The walls of the alveoli contain a protein called elastin.
- Elastin is elastic - it helps the alveoli return to their normal snap after inhaling and exhaling air.
- Gas exchange in the alveoli
- Oxygen diffuses out of the alveoli and into the haemoglobin in the blood.
- Carbon dioxide diffuses into the alveoli from the blood and is breathed out.
- Factors affecting the rate of diffusion
- Structure
- Air is forced out of the lungs.
- It is a passive process - it doesn't require energy.
- A steep concentration gradient of oxygen and Carbon dioxide.
- Alveoli and gas exchange
- Factors affecting the rate of diffusion
- A thin exchange surface (short diffusion pathway)
- A large surface area - lots of very small alveoli means there's a large surface area for gas exchange.
- Alveoli structure
- Each alveolus is made from a single layer of thin, flat cells called the alveolar epithelium.
- The walls of the capillaries are made from capillary endothelium.
- The walls of the alveoli contain a protein called elastin.
- Elastin is elastic - it helps the alveoli return to their normal snap after inhaling and exhaling air.
- Gas exchange in the alveoli
- Oxygen diffuses out of the alveoli and into the haemoglobin in the blood.
- Carbon dioxide diffuses into the alveoli from the blood and is breathed out.
- Factors affecting the rate of diffusion
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