B4-035 O2 and CO2 Transport Flashcards
CO2 diffuses [….] than O2
more readily
perfusion or diffusion limited?
gas equilibrates early along the length of the capillary
perfusion limited
perfusion or diffusion limited?
exchange can only be increased if blood flood increases
perfusion limited
perfusion or diffusion limited?
O2 (normal health), CO2, N2O
perfusion limited
perfusion or diffusion limited?
gas does not equilibriate by the time blood reaches the end of the capillary
diffusion limited
perfusion or diffusion limited?
O2 (empysema, fibrosis) CO
diffusion limited
O2 diffuses […] across the alveolar membrane
slowly
CO2 diffuses […] across the cell membrane
rapidly
dissolved oxygen contributes to the […] of oxygen in blood
partial pressure
[…] dictates hemoglobin/O2 characteristics
partial pressure of oxygen in blood
very little O2 is carried in the […]form
dissolved
- partial pressure of O2 in blood
- determined by molecules of O2 contained in the liquid phase
blood PO2
right shift of curve results in
more oxygen being unloaded where needed
left shift of curve indicates
more O2 saturation to carry oxygen where its needed
downward shift of curve indcates
change in Hemoglobin amount
upward shift of curve indicates
increase in dissolved PO2
a-v O2 difference reflects
oxygen consumption by the body
three forms of CO2 in blood
HCO3-
HbCO2
dissolved
as CO2 enters the blood […] leaves O2
hemoglobin
in lungs, oxygenation of Hb promotes dissociation of
H+
shifts equilibrium toward CO2 formation
in lungs, oxygenation of Hb promotes H+ dissociation, CO2 is
released from RBCs
causes decreased transit time through capillaries
exercise
pressure gradient of […] is much higher
O2
pressure gradient of […] is lower
CO2
10x less than O2
a thicker capillary membrane will have a greater effect on […] diffusion
O2
oxygen has a more difficult time diffusing across the membrane due to the
high pressure gradient
a severe reduction in PaO2 will trigger compensatory
hyperventilation
factors that effect DLO2
- surface area available for diffusion
- distance from alveolus to RBC
an increase in the capillary membrane thickness can be detected by
testing the diffusing capacity of CO
PO2 of 45mm Hg is a Hb saturation of
75%
PO2 of 100 mmHg is a Hb saturation of
95%
normal O2 content in blood
20 ml/dl
higher than normal hemoglobin is a compensatory mechanism for
long term hypoxia
will still have normal O2 content, even though Hb saturation is low
PPL at end of expiration at FRC is
-5 cm H2O
a less negative PPL indicates
reduced elastic recoil
high compliance
increased compliance means easy to
inflate
less elastic recoil
hypoxia causes pulmonary arterial
vasocontriction
increasing arterial blood PO2 only affects
dissolved O2, minimal change in graph
arterio-venous O2 difference is affected by
O2 consumption in the tissues
a decreased in PCO2 would signal
hyperventilation
breathing 100% O2 causes a several fold increase in
PaO2
if cardiac ouput and O2 consumption remain unchanged, the arterio-venous O2 difference
remains unchanged
Fick Principle
VO2=Q x (CaO2-CvO2)
how would anemia alter the PO2 and the total O2 content?
PO2 remains normal
Total O2 content is low
Hb is well oxygenated, just not enough Hb
will mild/moderate anemia increase ventilation?
no, PO2 is normal so chemoreceptors do not fire
if lung function is normal, the difference between alveolar and arterial PO2 is
5-10 mmHg
O2 carrying capacity is determined by
2
- Hb concentration
- O2 affinity
PCO2 at normal alveolar ventilation
40 mmHg
PCO2 of >40 mmHg indicates
hypoventilation
