Lungs
1kg average sized adult
- 4-6L volume (basketball)
Nouse, mouth, trachea and primary bronchi function
- Warm, humidify and filters air
- Converting it from ambient temperature, pressure and saturation (ATPS) to body temperature, pressure and saturation (BTPS) ambient to body temperature
Dalton’s Law
partial pressure = % concentration x total pressure of gas mixture
How TF do lungs expand
- Adhere to chest wall following movement of chest
Any change in thoracic cavity volume = change in lung volume
Diaphragm
- Large dome shaped sheet of striated Musculo-fibrous tissue
- Airtight separation between abdominal and thoracic cavities
Contracts and flattens/moves down into abdominal cavity (moves 10cm)
- Airtight separation between abdominal and thoracic cavities
Inspiration
Diaphragm contracts, flattens and moves down (10cm)
- Increased volume, decreased intrapulmonic pressure
Expiration
Diaphragm compression - ribs down
- Decreased volume = increased pressure
Inspiration During Exercise
- increased thorax
- decreased thoracic pressure
- lifted ribs
Muscles used during inspiration in exercise
- diaphragm and external intercostals
- accessory muscles such as pec minor, serratus anterior, scaleni muscles and sternocleidomastoid
Expiration During Exercise
- diaphragm moves up
- ribs lower down
Muscles used during expiration in exercise
- abdominal muscles (contract and increase intra-abdominal pressure forcing diaphragm up)
- internal intercostals (lower ribs and reduces thoracic dimensions)
Anatomical Dead Space %
fills up 30% of tidal volume at rest
Why is PO2 in trachea different than in alveoli
Due to alveolar air where
- CO2 enters alveoli from venous blood
- O2 continualy enters alveoli from breath
