RESP- Pulmonary Ventilation Flashcards
what factors are lung volume and capacities dependent on
Age, sex, height
compliance, obstruction / damage
what is pulmonary ventilation
movement of air from the atmosphere to the gas exchange surface of within the lung
what is pulmonary ventilation used for
maintaining oxygen and carbon dioxide concentration gradients between alveolar air and arterial blood
what factors are needed for adequate transport of oxygen from the atmosphere to respiring tissues
alveolar ventilation, gas exchange, cardiac output
how are pressure gradients between alveoli and blood maintained
adequate ventilation
what is the relationship between partial pressure, ventilation and gas exchange
increase in ventilation = increase in partial pressure gradient between alveoli and the blood = increase in gas exchange
what is the relationship between partial pressure of carbon dioxide in the alveoli and an increase in ventilation
as ventilation increases partial pressure of carbon dioxide decreases
what is the equation for ventilation
V (minute volume) = Vt (tidal volume, amount of air inhaled in each breath) x f (frequency, number of breaths per minute)
where does gas exchange take place
the alveoli
how much air remains in the lungs and airways at the end of expiration (residual volume)
150 ml
what is the equation for alveolar ventilation
Va = (Vt - Vd) x f
what is the ideal gas law
PV=nRT
what is boyles law
P= proportional to n/V
pressure, number of moles, volume
what causes air to flow into the lungs
the diaphragm contracts and the thoracic cavity expands - this increases lung volume and decreases alveolar pressure
this creates a large pressure gradient between the alveoli and the atmosphere meaning air flows into the lungs
what causes air to flow out of the lungs
the diaphragm relaxes, so the lung volume is reduced - thoracic cavity volume decreases
this causes an increase in pressure in the alveoli
meaning pressure in the alveoli is greater than in the atmosphere so air flows out of the lungs
what is the pleural cavity
fluid filled space between the membranes (Pleura) that line the chest wall and each lung
what is the function of the pleural cavity
helps to reduce the friction between the lungs and the chest
what properties does the pleural cavity have and what do these achieve
sealed, fluid filled
means it resists changes in volume
outline the process of inspiration
respiratory muscles (diaphragm) contracts
volume of thoracic cavity increases
intrapleural pressure becomes more negative
lungs expand, increasing volume
alveolar pressure decreases below atmospheric pressure
air moves down the pressure gradient through airways into the alveoli equalising pressure difference
outline the process of expiration
respiratory muscles (diaphragm) relax, lungs recoil due to elastic fibres
volume of thoracic cavity decreases
intrapleural pressure increases
lungs are compressed
pressure in alveoli increases above atmospheric pressure
air moves down the concentration gradient into the atmosphere, deflating the lungs and equalising the pressure difference
what is a pneumothorax
entry of air into the pleural cavity resulting in a loss of intrapleural pressure and collapse of lung tissue
what happens to the pressure gradient if either pleural membrane is ruptured
pressure gradient between the pleural cavity and surrounding environment will cause air to enter until intrapleural pressure = atmospheric pressure
entry of air into the pleural cavity increases pleural cavity volume
elastic recoil of lung tissue and the expansion of the chest during inspiration can potentially draw further air into the pleural space