Anatomy of Chest Wall and Mechanics of Breathing Flashcards
What does Boyle’s law state
The pressure exerted by a gas is inversely proportional to its volume (P^a 1/V).
What does Dalton’s law state
The total pressure of a gas mixture is the sum of the pressures of the individual gases
What does Charles law state
The volume occupied by a gas is directly related to the absolute temperature (v^a T)
What does Henry’s law state
The amount of gas dissolved in a liquid is determined by the pressure of the gas and its solubility in the liquid
In which direction do gases (singly or in mixtures) move
From areas of high pressure to areas of low pressure
How many lobes is the right lung divided into
3
How many lobes is the left lung divided into
2
Name the right lung lobes
Superior lobe
Middle lobe
Inferiorlobe
Name the left lung lobes
Superior lobe
Inferiorlobe
What are both lungs enclosed in
Two pleural membranes for each lung
What passes through the thorax
Esophagus and aorta between the pleural sacs
What is between the surfaces of pleural membranes
An extremely thin layer of intrapleural fluid
What is the interior of the thorax covered by
Pleural membranes
What does the visceral pleural membrane coat
Outer surface of the lung
What does the parietal pleural membrane coat
Inner surface of rib
What is found between the visceral and parietal pleural membrane
Pleural fluid
How are the lungs bound (‘stuck’) to the rib cage
Through the relationship of the pleural membranes
What is pleurisy
Inflammation of the pleura
What can the intrapleural pressure be described as in a normal lung at rest
Subatmospheric
What does elastic recoil do to the normal lung at rest
Elastic recoil of the chest wall will try to pull the chest wall outward
Elastic recoil of the lung creates an inward pull
What is a pneumothorax
Air in the chest wall
What occurs in a pneumothorax
Sealed pleural cavity is opened to the atmosphere
Air will flow in
Ribcage will expand slightly
Lung will collapse to an un-stretched size
Why does breathing occur
Because the thoracic cavity changes volume based on Boyles law
Simplify Boyles law
Increase volume = decrease pressure
Decrease volume = increase pressure
What does inspiration use
External intercostal muscles
Diaphragm
Sternocleidomastoids
Scalenes
What does expiration use
Passive at rest
Uses internal intercostal and abdominal muscles during severe respiratory load
In what state is the diaphragm after relaxed expiration and before inspiration
At rest
What does the pump handle motion do
Increase the anterior-posterior dimension of the ribcage
What does the bucket handle motion do
Increase the lateral dimension of the rib cage
What is asthma
An over-reactive constriction of bronchial smooth muscle
It increases resistance making expiration difficult
What occurs during inspiration
The diaphragm contracts to increase thoracic volume and the airways are pulled open by the physical forces of inspiration
What occurs during expiration
The diaphragm relaxes to decrease thoracic volume and the airways are compressed by the physical forces of expiration
What are the three relevant pressures
Intra-thoracic (Alveolar) Pressure (P A)
Intra-pleural Pressure (P ip)
Transpulmonary pressure (P T)
What is intra-thoracic (Alveolar) Pressure (PA)
The pressure inside the thoracic cavity (i.e. pressure inside the lungs)
It can be negative or positive when compared to the atmospheric pressure
What is intra-pleural Pressure (Pip)
The pressure inside the pleural cavity
This is always negative in healthy lungs
What is transpulmonary pressure (PT)
The difference between the alveolar pressure and intra-pleural pressure
This is always positive in healthy lungs because P ip is always negative (PT = PA – Pip)
What is the bulk flow of air between the atmosphere and alveoli proportional to
The difference between the atmospheric and alveolar pressures and inversely proportional to the airway resistance: F = (P atm- P A)/R
When does Patm= PA
At the end of an unforced expiration, between breaths
Why does P atm= PA
Because no air is flowing
The dimensions of the lungs and thoracic cage are stable as the result of opposing elastic forces
What does a transplumonary pressure create when there is a subatmospheric pressure
Pressure that opposes the forces of elastic recoil
How is the amount of air that flows into lungs determined
By airway resistance at any given pressure difference between atmosphere and alveoli
What is a major determinant of airway resistance
The radii of the airways
