5.2 - Gas Laws and Ventilation Flashcards
What is the total pressure of a mixture of gases?
sum of partial pressure of individual gases
What factors determine the amount of gas dissolved in a liquid?
- partial pressure of the gas
- solubility of the gas in the liquid
How is partial pressure of an atmospheric gas calculated?
P X % of gas in atmosphere
atm
What does Boyle’s law explain?
The rs b/w volume and pressure
p1v1 = p2v2
What are the driving forces of air flow during ventilation?
alveolar pressure changes which are caused by changes of the thoracic cavity during inspiration and expiration
TRUE OR FALSE:
The lungs have their own muscles by which they can change volume
FALSE:
Lungs depend on muscles located in the chest wall
What is the structure of lungs?
passive elastic structures like balloons
What factors contribute to the volume of the lungs?
transpulmonary pressure
- difference between alveolar pressure intrapleural pressure
degree of elasticity of the lungs
What is the pressure inside and outside of the lungs?
inside: alveolar pressure
outside: pressure in the intrapleural fluid
What is the function of the airways?
- warm up air to 37 degrees celcius to maintain core body temp and protect alveoli
- add water vapour to air to prevent drying of epithelia
- filter out foreign material
What is the cellular process of filtering out foreign material?
- airways are lined with ciliated epithelia that secrete watery saline solution
- cells move Cl- from ECF into cell via NKCC
- Cl- transported to lumen of airway via apical anion channel
- Na+ moves between cells from ECF to lumen
- [] gradient of NaCl draws water towards the lumen creating the watery saline solution
What are cilia covered with?
covered with mucus
What secretes mucus and how is it secreted to the digestive tract?
goblet cells secrete muscus
mucus contains immune cells that kill invaders
mucus moved up to pharynx (mucus escalator)
transfered to disgestive tract where additional bacteria are destroyed
What are medical conditions that complicate ventilation?
cigarette smoking
- paralyzes cilia
- infections lead to smoker’s cough
cystic fibrosis
- inherited condition
- mutations in Cl- channel, not transported in lumen
- prevents appropriate secretion of water into the mucus
- thick and sticky in airways
- blocks airways
- prevents removal of bacteries = repeated infections
- over active immune cells start destroying lung
What are the steps of inspiration?
- somatic motor neuron trigger contraction of diaphragm and inspiratory muscles
- thorax expands, thoracic volume increases
- alveolar and intrapleural pressure decreases
- lungs expand resulting in air flowing into lungs
What are the steps of expiration?
- somatic motor neurons stop firing
- diaphragm and thoracic muscles relax, returning thorax to original position = decreased volume
- alveolar and intrapleural pressure increases
- lung volume decreases due to air flowing out of lungs due to elastic recoil of the lung
During quiet breathing, expiration is a ____ process. What does it depend on?
passive
depends on elastic recoil of lungs and thoracic muscles
During heavy breathing, expiration is a ____ process? What does it depend on?
active process, depends on contraction of internal intercostals and abdominal muscles
TRUE OR FALSE:
intrapleural pressure is sub-atmospheric and decreases during foetal development
FALSE:
sub-atmospheric and INCREASES during foetal development
How does the lungs stay expanded and open?
when outside pressure in the pleural fluid is low, pressure inside the lungs stay high, thus expanded and open
What is pneumothorax?
When the lungs collapse due to absence of pressure difference
- air gets into the pleural cavity and intrapleural pressure increases
What is the treatment for pneumothorax?
Apply suction and remove the air and seal the hole
List and define the factors of breathing
compliance of the lungs: stretchability
resistance to airflow in airways
