Lecture 38: Gas Transport: Oxygen and Carbon Dioxide Transport Flashcards
A woman has low hemoglobin because she has a heavy period, what is expected to decrease? A.Arterial PaO2 B: Arterial Hb saturation C. Dissolved O2 D. Total O2 content
D= that is the only thing that changes with anemia
what are the two states in which oxygen is transported ?
1- In a dissolved state in plasma:
solubility of oxygen is 0.003 ml O2 per dl/plasma
Dissolved O2=PO2* solubility
100X.003= 0.3 ml/dl
O2 consumption is over 250 ml and pumping 83 L of blood per min is not realistic.
2- Bound form in plasma to hemoglobin in RBCs.
binding reversibly to oxygen
Calculate the max amount of oxygen that can be bound to hemoglobin.
1 gm of hemoglobin can bind 1.36 ml O2
if blood has 15g
1.36*15= 20.4ml O2 is they carrying
Calculate the max amount of oxygen that can be bound to hemoglobin, carrying capacity…
1 gm of hemoglobin can bind 1.36 ml O2
if blood has 15g
1.36*15= 20.4ml O2 is they carrying capacity
What is the equation for saturation of oxygen?
SO2= HbO2 content/ HbO2 capacity *100
content= actual capacity= what it can
hemoglobin needs to be in ____ state to bind to oxygen
relaxed
what is the shape of the saturation curve ?
sigmoidal
slide 13
As you increase the PO2 of oxygen Hb saturation _____ and O2 content _____
increases, increases
the graph then plateaus at 100ml… Once all Hb are filled the hb cannot bind oxygens
What occurs at the plateu phase of the curve? where does it occur? what phase?
at Alveolar PO2 you can get over 90% saturation… this occurs at the loading phase in the lungs…
( same graphs) What occurs at the steep portion of the curve ( box)? where does it occur? what phase is it?
small changes of partial pressure O2 cause large changes in HB saturation and content. this usually occurs in the tissues….
this phase is considered the unloading phase
what does P50 tell you?
when 50% of hemoglobin binding sites are full
look at pic
ex look at y axis get half then track down to x axis
what occurs if you have an increase in P50?
O2 dissociation curve shifts right. it means that hemoglobin has a lower binding affinity for oxygen.. theres a lot more oxygen
If you have decreased P50 what occurs?
Shift left….you have smaller P50, the hemoglobin has a higher affinity
what 4 things increase P50?
aka shifts right/ easier unloading lower affinity
- increase in temperature
- decrease PH
- increase CO2
- high 2,3 bisphosphoglycerate
what is the Bohr effect?
when there is an increase in PCO2 increase in acid then it shifts right, less affinity for oxygen
what is the affect of alkalinity in the blood?
then the graph shifts left causing more affinity to oxygen
also low temperature and low CO2 will do this
what occurs in the O2 saturation curve if you have anemia? what causes the symptoms
Saturation will not fall because all of the available O2 binding sites are full, (SaO2 is normal)
PaO2 is normal
Saturation is normal.
less binding sites exist in total so the O2 content is decreased, hypoxia causes their symptoms…
Its like having less hemoglobin molecules available to bind the oxygens.
if me and someone else have 100% oxygen saturation all the sites are filled even if I have 2 hemoglobin and them 1
What occurs if you have polycythemia? what happens to viscosity ?
- you have increased RBCs, and carrying capacity but you have no change in affinity, only more binding sites for O2.
- increased blood viscosity
- bleed them is better
what occurs in CO poisoning? to affinity? graph shift where? P50 increases or decreases? oxygen content? phenotype of blood? what are the physical symptoms?
- Increased affinity for CO
- shifts left from normal Oxygen binding
- decreases P50 and oxygen has a hard time unbinding to get released to the tissues
arterial pressure and dissolved oxygen the same
oxygen content decreases
CHERRY RED
brain affected first, slow rxn time, blurred vision, coma..
how do you treat a carbon monoxide poisoning?
remove person from the source, add 100% oxyge, mix with 5% CO2 to improve alveolar ventilation.
Review: what is bulk flow?
Conducting system: many gas molecules moves from trachea to alveoli…
driving pressure is the pressure gradient
Review: what is diffusion?
that’s how gas moves from alveoli to blood or from blood to tissues
what does diffusion depend on?
pressure gradient, decreased thickness of membrane, increased surface area, diffusion coefficient
what are the barriers that the Oxygen and CO2 have to pass in the respiratory membrane to go from the alveolus to the RBC?
alveolar epithelium> Fused basement membranes of endothelial cells> capillary endothelium
( squamous epithelial cell nucleus)
AFC
