Anatomy of chest wall and mechanics of breathing Flashcards
Boyle’s Law
The pressure exerted by a gas is inversely proportional to the volume
Do gases move from low to high or high to low pressure?
High to low
What 3 structures bind the lower respiratory tract?
Ribs, Spine and diaphragm
What lines the lungs and interior thorax?
Pleural membranes
What kind of fluid fills the pleural sac?
Intra pleural fluid
What are the 2 types of pleural membranes (pleura)?
Parietal and visceral
What causes the lungs to “stick” to the rib cage?
The pleural membranes
Pleurisy
Inflammation of pleura
Pneumothorax
The abnormal collection of air in the pleural space that causes an uncoupling of the lung from the chest wall
Is intra pleural pressure positive or negative in comparison to atmospheric pressure?
Negative
Sub atmospheric
Due to elastic recoil state what direction the ribs and lungs want to go
Ribs - want to pull chest outwards
Lungs - want to pull inwards
What is the name of the force which sticks the ribs and lungs together
Cohesive force
Muscles used for inspiration (4)
External intercostals
diaphragm
sternocleidomastoids
Scalenes
What muscles does expiration use 1- at rest and 2 - during severe respiratory load?
1 - None
2 - Internal intercostals and abdominal muscles
State of diaphragm at rest
Relaxed after expiration and before inspiration
State of diaphragm during inspiration
Contracted as thoracic volume increases as the diaphragm collapses
State of diaphragm during expiration
Relaxed as the diaphragm rises and thoracic volume decreases
Intercostals - pump handle explanation
Anterior-posterior dimension
Vertebrae->rib->sternum
Rub moves up to increases protrusion from anterior
Intercostals - Bucket handle explanation
Lateral dimension to make the chest wider
What is asthma?
Over reactive constriction of bronchial smooth muscle which therefore increases the resistance making expiration difficult
What forces are airways pulled open by?
Physical forces of inspiration
What forces are airways compressed by?
Physical forces of expiration
What happens to the lung in pneumothorax? Why?
The sealed pleural cavity is opened causing air to flow in from high atmospheric pressure to the lower intrapleural pressure and do the lung collapses to the un stretched size as it uncouples from the chest wall
Alveolar pressure (PA)
Pressure in the lungs which may be positive or negative
