Physio Review Flashcards
How can we calculate the O2 in the alveoli?
PAO2= PiO2-(PaCO2/R)
What is PiO2
the amount of inspired O2
How do we calculate PiO2
[Patm-47]*O2 capacity Ex (167mmHg-47)*.21
Oncre we have the PAO2, what do we do.
Take the A-aO2 gradient, to tell us if there is a diffusion problm. Subtract the alveolar O2 we solved from the arterial O2. If the answer is <12, there is not a diffusion problem.
Respiratory alkalosis in acute and chronic
acute expected[HCO3]=24-2((40-PaCO2)/10)) Chronic use 5 instead of 2
What stimulates our peripheral chemoreceptors
decrease in O2 Increase in CO2 Increase in H Hypoxia and hypercapnia
What do peripheral CR do?
Increase frequency if breathing (f) Increase tidal volume
What structures will be affected by an activation of perhpheral CR
frequency- Pre-botzinger Tidal volume- DRG
If we increase f and tidal volume, what we are doing?
Increasing minute ventillation Thus, WE ARE HYPERVENTILLATING. =increase in PaO2 and decrease in PaCO2;
What is the flat line of the Hb-02 curve?
Safety margin. Given a large change in partial pressure of O2, we have a small change in our O2 saturation
What will happen when moving from a seated position to supine in a normal person?
Decrease in TLC
Decrease in ERV
Increase in IRV
RV does not change
What will happen when moving from a seated position to supine in a obsese person?
Decrease in TLC
Decrease in IRV
No change in ERV
What changes in response to body positioning?
TLC
What changes will you see in obstructive diseases?
Increase in TLC and RV
Decrease in FEV1
Decrease in FEV1/FVC
Restrictive DZ
- FVC
- FEV1
- FEV1/FVC ratio
- TLC
- FVC- decreased
- FEV1- decreased
- FEV1/FVC ratio- normal or high (80% or more)
- TLC- decreased
In an obstructive lung disease, how would compliance and elasticity be affected?
increase compliance
decrease elasticity
COPD is obstructive. Why would there be less O2 diffusion?
decrease in SA
Fibrosis is restrictive. Why would there be less O2 diffusion?
Increase in thickness of traveling diameter
In restrictive diseases, what happens to compliance and elasticity
Decrease in compliance
Increase in elasticity
what happens during a pneumothorax
- Blood will shunt to the lung that is not collapsed (via NO)
- Blood will stop going to collapsed lung (vasoconstriction via thromboxane 2 and endothelin 1)
Oxygen in the alveoli
PAO2= PiO2- PaCO2/R
PiO2
(Patm- 47) * oxygen capacity (ex.21)
RQ for infusion with glucose
1
RQ for infusion with fats
0.7
RQ during fasting
0.7
RQ furing a hard run
increases
Always assume RQ is
.8
What happens to the resistance to blood flow when we get closes to FRC?
Resistance is lowest.
As you move to TLC or RV, resistance INCREASES
Zone 1
Alveolar ventilation- higher or lower
V/Q- higher or lower
PaO2- high or lower
PaCO2- higher or lower
Alveolar ventilation- higher or lower
V/Q- higher or lower
PaO2- high or lower
PaCO2- higher or lower
which receptors help us maintain a sleeping/resting state
CENTRAL CHEMORECEPTORS
-pH of the CSF-
What happens during a pulmonary thromboembolism?
results in areas of the lung that are ventilated, but not perfused, causing VQ ratio to go to infinity and increase alveolar dead space.
PaO2 of the affected alveoli will be the same as the inspired air via ventilation cuz no gas exchange occurs.
What happens to areas fof the lung that are perfused, but not ventilated?
Constitute areas of shunting (venous admixture)
Characterized as a V/Q ratio equal to 0 and having a PAO2 value that equillibriutes with mixed venous blood
