Pulmonary ventilation Flashcards
What do lung volumes and capacities depend on
lung volumes and capacities depend on factors like:
-age
-sex
-height
-long properties (compliance)
What is pulmonary ventilation definition
Pulmonary ventilation-movement of air from the atmosphere to gas exchange surfaces within the lungs. This is required to maintain O2 and CO2 gradients between alveolar air and arterial blood
What does adequate transport of O2 from atmosphere to respiring tissues depend on
Adequate transport of O2 from atmosphere to respiring tissues depend on healthy levels of alveolar ventilation, gas exchange, and cardiac output
Explain concentration of CO2 and O2 in inhalation
-Alveolar air= very high O2 and very low CO2
-movement of gas via breathing
-alveolar air= high O2 and low CO2
-capillary blood has low O2 and high CO2 after diffusion
What happens if there is increased ventilation
increased ventilation= increased partial pressure gradient (between alveoli and blood)
Increased gas exchange
What is minute volume
minute volume= the total volume of air inhaled in all breaths over one minute
What is the equation for minute volume
minute volume= Tidal volume (mL) x frequency (min-1)
What is tidal volume and frequency
Tidal volume= the volume of air inhaled in each breath
Frequency= frequency, the number of breaths per minute
Explain how the lungs contain a mixture of ‘fresh’ and ‘stale’ air
Gas exchange only takes place in the alveoli, the air must first pass through the airways.
The respiratory system is a two way system; air enters and leaves via the same path. The residual volume of air remains in the airway and lungs at the end of expiration.
‘Fresh’ and ‘stale’ refers to air that has just entered the respiratory system from the atmosphere vs the air that has entered the lungs during a previous breath
Explain the equation for alveolar minute volume
Alveolar minute volume= tidal volume - dead space volume x frequency
What is the definition of alveolar minute volume and dead space volume
alveolar minute volume= the total volume of fresh air entering the alveoli across all breaths over one minute
Dead space volume= the volume of air remaining in the respiratory system at the end of expiration
Explain how gases move through a pressure gradient
gases naturally move from areas of higher pressure to lower pressure until equilibrium is reached
Give the ideal gas law equation
pV= nRT
P= pressure
V=volume
N=moles
R= gas constant
T= temperature
Explain boyle’s law
Boyle’s law- the relationship between volume and pressure is inversely proportional. When volume increases, pressure decreases
What do changes in lung volume cause
-Changes in lung volume induce changes in alveolar pressure, which generates pressure gradients between the alveoli and atmosphere causing air to flow.
Explain the process of inhalation and exhalation
inhalation:
1) diaphragm contracts
2) thoracic cavity expands
3) alveolar pressure decreases
Exhalation:
1) diaphragm relaxes and lung recoils
2) thoracic cavity volume decreases
3) alveolar pressure increases
Explain what the pleural cavity is
pleural cavity- the fluid filled space between the membranes (pleural) that line the chest wall and each lung
-its presence reduces friction between lungs and chest during breathing
What are the properties of the pleural cavity
properties of the pleural cavity:
-sealed, fluid filled
-resists changes in volume
-changes in the volume of thoracic cavity result in changes in lung volume
What does the opposing elastic recoil of the chest wall and lungs result in
the opposing elastic recoil of the chest wall and lungs result in the pressure within the pleural cavity being sub atmospheric
What is negative and positive pressure
negative pressure= lower number of molecules per volume —> generates collapsing force
Positive pressure= increased number of molecules per volume —> generates expanding force
Explain in depth the process of inspiration
Inspiration:
1) respiratory muscles (diaphragm) contracts)
2) volume of thoracic cavity increases
3) intrapleural pressure becomes more negative
4) lungs expand, increasing volume
5) PAlv (alveolar pressure) decreases below PAtm
6) Air moves down pressure gradient, through airways into alveoli, expanding the lungs
Explain in depth the process of expiration
Expiration:
1) respiratory muscles (diaphragm) relax, lungs recoil due to elastic fibres
2) volume of thoracic cavity decreases
3) intrapleural pressure increases
4) lungs compressed, volume decreases
5) PAlv increases above PAtm
6) Air moves down pressure gradient into atmosphere, deflating lungs
Explain what happens in pneumothorax
Pneumothorax involves entry of air into pleural cavity, loss of negative intrapleural pressure and collapse of lung tissue.
What happens if either pleural membrane is ruptured
if either pleural membrane is ruptured, the pressure gradient between the pleural cavity and surrounding environment will cause area to leave until intrapleural pressure is the same as atmospheric pressure
