The Lungs

The Lungs

Main function
1. Allow gaseous exchange between air in the lungs and blood in the capillaries
Glands
1. Secretes mucus that traps dust and pathogens
Cilia
1. Removes mucus containing particles of dust that might be inhaled, this stops these getting into the lungs
Cartilage
1. Supports the trachea- prevents it from collapsing. Allows breathing to occur and prevents suffocation
Oesophagus
1. Behind the trachea. Allows us to swallow and breathe at the same time
Gaseous Exchange
1. Occurs in the alveoli
  1. Alveoli surrounded by blood capillaries
2. Carbon dioxide diffuses from the blood and oxygen diffuses from the alveoli
3. Alveoli have large surface areas + short diffusion pathway- 1 cell thick walls
Inspiration
1. 1. Intercostal muscles contract
2. 2. Ribs move up and out
3. 3. Diaphragm contracts, moves down and flattens
4. 4. Thorax increases in size
5. 5. Vacuum created in the lungs, air rushes down the trachea into the lungs
Expiration
1. 1. Intercostal muscles relax
2. 2. Ribs move in and down
3. 3. Diaphragm relaxes, moves up and becomes arched
4. 4. Thorax decreases in size
5. 5. Air is forced out of the lungs
Increased Breathing Rate
1. 1. During exercise the muscles respire more rapidly
2. 2. This leads to increased concentration of carbon dioxide in the blood
3. 3. Increased concentration detected by chemoreceptors in the carotid artery
4. 4. Impulses sent to the medulla in the brain
5. 5. Increased frequency of impulses from the medulla to the intercostal muscles and the diaphragm
6. 6. Intercostal muscles and diaphragm contract more frequently
7. 7. The rate and depth of breathing increases

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	Created by s30992 almost 12 years ago