the anatomy of ventilation Flashcards
define pulmonary circulation
the physical movement of air into and out of the respiratory tract
what’s the function of pulmonary ventilation? (2)
ensure continuous supply of oxygen
prevents build up of CO2
what 2 principles does pulmonary ventilation rely on?
- Boyles law
- air flows from an area of high to low pressure
what’s Boyle’s law?
the pressure of a given quantity of gas is inversely proportional to its volume
as volume increases, pressure
decreases— and vice versa
when will air enter lungs?
when atmospheric pressure is greater than the pressure inside the lungs
when will air leave the lungs?
when pressure inside the lungs is greater than atmospheric pressure
what is atmospheric pressure at sea level?
760mmHg
how do atmospheric and intrapulmonary pressure interact when at rest in respiratory cycle?
they are equal/ the same
what happens during ispiration?
lung volume increases, pressure inside decreases, lower than atmospheric pressure, air moves in
what happens during expiration?
lung volume decreases. pressure inside increases, air moves out as pressure is higher in lungs than atmospheric pressure
how can thoracic volume increase?
increasing vertical diameter
increasing anterior posterior diameter
increasing transverse diameter
how is vertical diameter increased?
contraction of diaphragm
what percentage increase in thoracic capacity is the diaphragm responsible for?
75%
how is anterior posterior and transverse diamaters increased?
elevation of the ribs
what percentage increase in thoracic capacity is the elevation of the ribs responsible for?
25%
what happens when the ribs elevate to increase anterior- posterior diameter?
they become more horizontal and the sternum is pushed forward- pump handle movement
what happens when the ribs elevate to increase transverse diameter?
the ribs are lowest near their middle and rise at each end- looking like a bucket handle
the middle of the rib rises moving away from the mid- line of the body, making the chest wider transversely
what’s the role of the pleura in ventilation?
a surface tension is created by the film of serous fluid between the parietal and visceral pleura ensuring that they can’t be pulled apart
what is intrapleural pressure in comparison to atmospheric and intrapulmonary pressures?
always lower
what creates this lower intrapleural pressure?
elastic recoil of the lungs
what’s pneumothorax?
a collapsed lung
what causes a pneumothorax?
accumulation of air or gas in the pleural cavitiy e.g. caused by a stab wound
pressure ends up similar to atmospheric so lungs can’t expand and contract as normal
lung collapses
how can pneumothorax be treated?
a chest drain put in the collapsed lung , removing the air in the pleural cavity and allows reinflation of the lung and a return to negative intrapleural pressure
