Anatomy of the chest and mechanics of breathing Flashcards Preview

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Flashcards in Anatomy of the chest and mechanics of breathing Deck (12):

mechanics of inspiration

-Diaphragm and external intercostal muscles contract which increases the volume of the thoracic cage
-pump handle and bucket handle movements of rib cage
-Pip becomes move negative
-Lungs expand
-Pa becomes sub atmospheric
-Air flows in


Mechanics of expiration

-Inspiration muscle cease contracting
-Elastic recoil of the chest and lungs causes the thoracic cage to return to its normal levels
-Pa increases so air flows out


Forced expiration

Internal intercostal muscles and the abdominal muscle contract to reduce the volume of the thoracic cage


What gas rule do expiration and inspiration follow?

Boyles Law: Pressure is inversely proportional to volume.
Gases tend to move from an area of high pressure to an area of low pressure.


What are the pleural membranes

1 bound to exterior lung surface- visceral
1 found to interior layer of ribs- parietal
Allow the lungs to stay bound to the rib cage
Pleural cavity contains pleural fluid


Different pressures

Alveolar or intra-thoracic pressure: Pa- pressure inside thoracic cavity
Intra-pleural Pip- always negative
Intra-thoracic : Pa-Pip -always positive


Changes in pressure during inspiration

In 2 seconds
Pa 0--(-1)--0 mmhg
Pip (-3)-- (-6) mmhg
Volume of air breathed in
500 ml


Changes in pressure during expiration

In 2 seconds
Pa: 0--1--0 mmgh
Pip : (-6)--( -3) mmhg
volume of gas exhaled
500 ml



Occurs when pleural cavity is pierced
The elastic recoil of the lung causes it to collapse
The elastic recoil of the rib cage pulls it out causing it to expand slightly
Pip goes from being negative to being close to Patm


Bulk flow

proportional to Patm-Pa
inversely proportional to resistance


pump movement and bucket handle movement

Pump movement: increases anterior-posterior rib cage
Bucket handle movement: increases lateral rib cage movement


Which are the accessory muscles in inspiration and expiration

Inspiration: sternocleidomastoid muscle and the scalene
Expiration: Internal intercostal and abdominal muscle