L12-13 Mechanics of Breathing and Gas Exchange Flashcards
define compliance
Ease with which lungs can be inflated
compliance formular
change in vol/change in press
what is compliance dependant on
- lung volume + size (high vol= low com)
- elastic recoil of lungs + chest
- surface tension
compliance in restrictive and obstructive diseases
r= low com o= high comp
what does surfactant do
• Larger alveolar
o gas flows down pressure gradient down path of least resistance // would naturally flow to bigger alveoli
o // surfactant (secreted by alveolar type ii cell)
• Lines + reduces pressures
o = even gas flow
which two forces keep alveolar open
transmural pressure grad + pulmonary surfactant
which two forces keep alveolar closed
pulmonary elasticity + alveolar surface tension
other than compliance, what also effects air flow
resistance
chief site of resistance in airway
bronchi
name 2 bronchodilators + receptors
• Albuterol, Epinephrine → ß2 adrenergic receptors)
name 2 bronchoconstri
• Environmental insults
Ach
explain lungs being ‘half full’
o RV prevent lungs from collapsing → less work to inflate lung
o RV ensures continuous gas exchange
spirometry diff in normal vs ob + res
ob= (dec ERC + sloped ex res= dec IRC
fractional gas of O + CO2
O= 0.21 CO2= 0.0004
PIO2 formula
(Pb- PH20 (47)) x 0.21
= 150ml
alveolar air o2 mmHg
104
alveolar air CO2 mmHg
40
what does alveolar Po2 depend on
o Alveolar ventilation- how much air you get into lungs
o Metabolism- oxygen consumption
factors affecting diffusion capacity (DL)
- Surface Area
- Respiratory Membrane Thickness
- O.6um - PP Difference of O2 & CO2
• CO2 lower gradient as more soluble than oxygen // don’t need as large - Diffusion Coefficient (D) of Gas
- CO2 more sol
VGas formula
= A/T xD(p1- p2)
when does full Hb saturation occur
1/3 cap length
diffusion amount diff b/w o2 and co2
o= 40 >104 c02 = 40 >45
what is the
Hb-O2 Dissociation Curve
effects on the Hb-O2 Dissociation Curve
- exercies= (uses o2 so po2 dec= offloading
- temperate
- pco2 + ph
what is the bohr effect
ow pH lowers affinity off combination
haldance effect
deoxygenated blood carries more CO2
chloride shift
when negative bicarbonate moves out of cell, to maintain electrical = Cl moves into cell
alveolar gas equation
PaO2= Pio2 - (paco2(40)/rq)
RQ=
0.8
