Anatomy of chest wall and the mechanics of breathing Flashcards
What is Boyle’s law
Boyle’s Law states that the pressure exerted by a gas is inversely proportional to to its volume (P a 1/V).
State Dalton’s law
Dalton’s Law states that the total pressure of a gas mixture is the sum of the pressures of the individual gases.
Describe Charle’s law
Charles Law states that the volume occupied by a gas is directly related to the absolute temperature (v a T)
What is Henry’s law?
Henry’s Law states that the amount of gas dissolved in a liquid is determined by the pressure of the gas and it’s solubility in the liquid
What encloses the lower respiratory system?
Thoracic cage
What attaches the lungs to the inner surface of the rib-cage?
Nothing
They are stuck together (or at least the pleura are held together) by the intrapleural fluid
What is Pleurisy?
Inflammation of the pleura
What is it called when the two pleural membranes separate from each other?
Pneumothorax
What muscles are used for normal inspiration?
Diaphragm and external intercostals
What accessory muscles can be used for inspiration if needed?
Scalene and sternocleidomastoid muscles in your neck
Pec major & minor
Latissimus dorsi
Serratus anterior, posterior superior
What muscles are used for expiration at rest?
None
Expiration is normally passive
What muscles can be used for forced expiration?
Internal intercostals & abdominal muscles
Describe how inspiration works
Diaphragm and Ext intercostals contract causing the volume of the lungs to increase
Greater volume = lower pressure (Boyle’s law)
Lower pressure inside the lungs compared to outside pressure causes air to move into the lungs
In what two ways do individual ribs move during inspiration, that causes an increase in the volume of the thoracic cage?
‘Pump handle motion’ increases anterior-posterior dimensions of the rib cage
‘Bucket handle motion’ increases lateral dimensions of the rib cage
What is the normal intrapleural pressure?
-3 mmHg
What creates the intrapleural pressure?
Elastic recoil of the chest (outward) acting against the elastic recoil of the lungs (inward)
If intrapleural pressure is the same as atmospheric pressure, whats happened?
Pneumothorax
What is the Transpulmonary pressure?
difference between alveolar pressure and intra-pleural pressure. ALWAYS positive (in health) because intrapleural pressure is always negative. PT = PA – Pip.
When is alveolar pressure most positive?
Expiration
When is intrapleural pressure greatest and why?
After expiration (but before inspiration)
This is when the volume of air in your lungs is lowest, so the force of elastic recoil of the lungs is highest
