Respiratory Physiology 1 Flashcards
In the lateral position, which lung has greater perfusion?
The dependent lung
In the lateral position, which lung has less ventilation?
The uppermost lung
In the lateral position, where is V/Q higher?
Ventilation and perfusion are higher in the lower (dependent) lung although perfusion is slightly better than ventilation so V/Q <1
In the lateral position, which lung has the lower PO2?
The dependent lung.
V/Q < 1 (degree of shunt)
In areas of shunt the alvelolar mixed gas tends toward mixed venous so PO2 is low and PCO2 slightly raised.
In the lateral position, which lung has the higher PCO2?
Dependent lung.
In the non-dependent lung V/Q >1 (ie degree of dead space)
Alveolar gas now tends towards inspired gas and so PO2 is raised but PCO2 is also low.
What lung volumes can spirometry NOT measure?
All except
- FRC
- residual volume
- TLC
What methods can measure FRC?
- body plethysmography
- nitrogen wash out
- helium wash in
Where on deoxyHb does 2,3 DPG bind?
The beta chains
What is 2,3, DPG formed from?
Product of glycolysis from phosphoglyceraldehyde in RBCs
How does 2,3 DPG affect oxygen utilisation by cells?
2,3 DPG shifts the O2 dissociation curve to the right.
Reduces O2 binding to Hb and therefore increasing O2 availibility for tissue utilization.
How do thyroid hormones affect 2,3 DPG?
They increase 2,3 DPG concentration in red cells
(as does growth hormone and androgens)
Can 2,3 DPG bind to fetal Hb?
No because fetal Hb doesn’t have beta chains
Where are peripheral chemoreceptors found?
Carotid and aortic BODIES
NOT carotid sinus
What do central chemoreceptors in the medulla respond to?
A rise in PaCO2 and CSF pH
**predominant ventilation control is central chemoreceptors in medulla**
Are peripheral chemoreceptors downregulated in the presence of chronic lung disease?
No
