Anatomy of Chest Wall and Mechanics of breathing Flashcards
How much pleural fluid is between the pleural membranes and what does it do?
3ml - lubricates them and keeps them stuck together.
Where do the pleural membranes become continuous?
the hilux of the lung - where all the stuff goes in
whats the membrane on the surface of the lungs called?
visceral
whats the membrane on the inside of the ribs called?
pariental
why is the relationship between the visceral and parietal pleura important for the inflation of the lung?
They are held together due to the pleural fluid, and attach the lungs to the inside of the rib cage. So when the ribcage expands, they expand too (although they want to recoil)
Which muscles are involved in inspiration?
Diaphragm and external intercostals (aided by scalene and sternocleidomastoid)
What muscles can be used for forced expiration?
internal intercostals and abdominal muscles.
What does forced expiration do?
It reduces thoracic dimensions and reduces the duration of breathing cycle and allows more breaths per min..
What type of motion increases the anterior - posterior dimensions of the rib cage?
‘Pump handle’
What type of motion increases the lateral dimensions of the rib cage?
‘Bucket handle’
What is Boyle’s law?
‘The pressure exerted by a gas is inversely proportional to its volume’ P a 1/V).
In terms of boyles law, why would air go into the lungs during inspiration?
Increase in thoracic volume > decrease in pressure > gas goes from high pressure to low > gas goes into the lungs
What is respiratory minute volume?
The volume of gas inhaled or exhaled per minute
What creates a sub atmospheric pressure in the intrapleura, that leads to a transpulmonary pressure that opposes the force of elastic recoil?
The opposite forces of the lungs and the chest wall
inspiration causes intrapleural pressure to become more negative. Explain?
Breath in, increase space, pulls pleural down, increases volume and decreases pressure.
What does the amount of air flow during ventilation depend on ?
the difference between the atmospheric pressure and then alveolar pressure. It is inversely proportional to air way resistance.
What is inter thoracic pressure?
alveolar pressure - pressure inside the thoracic cavity.
Can be negative or positive compared to atmospheric pressure.
What is intra-pleural pressure?
pressure inside the pleural cavity. Always negative, suction to keep lungs inflated.
What is transpulmonary pressure?
difference between alveolar pressure and inter pleural pressure. Always positive cos pip is always negative.
PT = Palv - Pip
What is pleurisy?
Inflammation of the pleural membranes - so they do not slide across each other smoothly
Does asthma make inspiration of expiration difficult? Why?
Expiration - as its passive. Since asthma is over- reactive constriction of bronchioles, the air cannot get back out well
explain pneumothorax.
the pleural cavity is sitting at a lower pressure than the atmosphere. If the sealed pleural cavity is opened to the atmosphere, air rushes in until the intraplureal pressure and atmospheric pressure are equal. Lungs collapse to unstretched size.
