Anatomy of Chest Wall and Mechanics of Breathing Flashcards
Gas Laws
Boyle’s
Dalton’s
Charles’s
Henry’s
Boyle’s Law
States that the pressure exerted by a gas is inversely proportional to its volume
Dalton’s Law
States that the total pressure of a gas mixture is the sum of the pressures of the individual gases
Charles’s Law
Sates that the volume occupied by a gas is directly related to the absolute temperature (v a T)
Henry’s Law
States that the amount of gas dissolved in a liquid is determined by the pressure of the gas and its solubility in the liquid
Importance of relationship between pleural membranes (2)
- Elastic recoil of lungs creates an inward pull
2. If pleural cavity is opened, air flows in and lung collapses to unstretched size
Parietal Sac
coats inner surface of the ribcage (can sense pain)
Visceral Sac
outer surface of lungs
What does the relationship between the parietal and visceral do
Lungs are effectively stuck to rib cage through this relationship
Pleurisy
Inflammation of the pleura
Increase in volume
Decrease in pressure
Decrease in volume
Increase in pressure
Gases move from
High pressure to low pressure
What muscles do inspiration use
External intercostal muscles
Diaphragm
Scalene
Sternocleiomastoids
What muscles do expiration use
Internal intercostal muscles
Abdominal muscles
Intra-thoracic (Alveolar) Pressure (PA)
Pressure inside the thoracic cavity (essentially pressure inside the lungs). May be negative or positive compared to atmospheric pressure
Intra-pleural Pressure (Pip)
Pressure inside the pleural cavity always negative
Describe the pump handle movement of Ribs
Anterior parts of the ribs move anteriorly
This action moves the sternum up and down
Describe the bucket handle movement of the ribs
This motion increases the lateral dimension of the rib cage and increases the transverse diameter of the thorax
Explain why intrapleural pressure is always less than alveolar pressure (intra-thoracic)
Pressure within the pleural cavity is negative
Pressure within the lungs is normally positive
The negative pressure creates a suction force and helps keep the lungs inflated
What is a Pneumothorax
Pressure within the pleural cavity becomes 0 as it is exposed to the atmosphere when the chest wall is punctures and lungs collapse
What is Asthma
Over-reactive constriction of bronchial smooth muscle. Expiration is difficult because airways are compressed by physical force as well as bronchial constriction
