INCOMPLETE !3.1 lung ventilation Flashcards
To meet the demands of gas exchange what is needed ?
- very large surface area
- very large number of very small compartments
- proximity to blood supply
Conducting airways continue of what ?
- trachea branches to primary bronchi
- further division to lobar (secondary) & segmental (tertiary) bronchi
- divisions continue until become bronchiole and terminal bronchioles
where does gas exchange occur ?
respiratory airways
what do respiratory airways comprise of ?
- respiratory bronchioles
- alveolar ducts
- alveoli
Each alveolus surrounded by a .1…
Branching blood vessels in the pulmonary circulation, forming a ..2.. like the airways
- capillary
- tree
What 2 features of the pulmonary circulation mean that no fluid should not form in the lungs ?
- low resistance
- low pressure
difference between pulmonary circulation and systemic system
It receives entire cardiac output so it’s supply driven
AND NOT deman led like systemic system
Typical pulmonary arterial pressure ?
14 - 18 mmHg (mean)
Typical systolic and diastolic pulmonary arterial pressure ?
systolic: 20-25
diastolic: 4-12
What’s the difference between what the hydrostatic and oncotic pressure gradient drive ?
hydrostatic pressure gradient -> drives fluid from the pulmonary microcirculation into the interstitium
oncotic (colloidal osmotic) pressure -> gradient favours movement of fluid in the opposite direction
What 3 factors does gas exchange which occurs via diffusion depend on ?
- area
- gradients
- diffusion resistance (nature of barrier & gas)
What are gradients in gas exchange created by ?
- alveolar air composition
- gases in blood returning to the lung
slide 11 area…
Values of pO2 & pCO2 of alveolar air which has a different composition to the atmosphere ?
pO2 normally 13.3 kPa
pCO2 normally 5.3 kPa
Typical values of pO2 and pCO2 in mixed venous blood, but varies with metabolism
pO2 = 6.0 kPa
pCO2 = 6.5 kPa
Why will oxygen diffuse into blood and carbon dioxide out ?
pO2 in alveolar gas(13.3) > pO2 in returning blood (6.0) (<—)
pCO2 in alveolar gas (5.3)< pCO2 in returning blood (6.5) (–>)
What makes up the 5 cell membranes, 3 layers of cytoplasm and 2 layers of tissue fluid for the nature of barrier with diffusion resistance ?
- diffusion through gas to alveolus
- epithelial cell of alveolus
- tissue fluid
- endothelial cell of capillary
- plasma
- red cell membrane
What are the 2 factors of nature of gases regarding diffusion resistance ?
- gases diffuse through gases at rate inversely proportional to molecular weight (big molecules diffuse slower, carbon dioxide slower than oxygen)
- gases diffuse through liquids at rate proportional to solubility (more soluble, faster diffusion & CO2 much more soluble than O2 so diffuses 21 times faster)
Compare speed of diffusion of CO2 and O2
CO2 diffuses much faster than O2 overall
approximately 21 times faster
What diseases will affect oxygen diffusion more ? (re-word Q!!)
Diseases that increase the amount of fluid