Transport of Oxygen and Carbon Dioxide in Body Fluids

Created by cbryce823 

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Folder C #9 11-17-2010

review: how do temp, pressure, and salt affect gas solubility?

increase solubility by:
decreasing temp
increasing pressure
decreasing salt

Partial pressure of oxygen (sea level, full humidity)

atmospheric: 152 mmHg
alveolar: 104mmHg (lower b/c mix of old and new air)
Venous: 40mmHg (on way back to lungs, nice [ ] gradient: 104:40

oxygen levels in plasma

0.3 ml O2/100 ml plasma

oxygen levels in blood (whole blood)

20 ml O2/100 ml plasma...

difference from 0.3 due to hemoglobin! 60x as much! can have larger metabolism with hemoglobin

anemia...

low levels of Red Blood Cells (RBCs)
reduced ability to transport oxygen

hemoglobin

similar across species
heme group...in the middle sits IRON...which can bind oxygen
2 Beta globins, 2 alpha globins

hemoglobin: fetal forms

slightly different protein
fetal heme group has a HIGHER affinity to oxygen than adult
we want oxygen from mom's blood to diffuse to baby's blood... preferentially moving O2 from mom to baby

expect to see this in chickens?

nope! no placenta...develop in egg instead.
over time, affinity decreases

why is the affinity between hemoglobin and O2 so important?

pick up and drop off

oxygen equilibrium curve axis

partial pressure of oxygen in the blood (x axis)
hemoglobin percent saturation (y axis)

what's the shape of the graph?

SIGMOID!...get the curves right...

oxygen binding to heme groups...

once one binds, the subsequent oxygens have an easier time binding due to the conformational change in the heme group...makes the curve rise faster with each subsequent oxygen added

RAPID loading and unloading of oxygen due to...

conformational shape induced by binding of oxygen to heme...

steep part of the curve

small change in [O2] has an enormous effect on % saturation
see the steep part in the lungs and tissues...
QUICK pickup and dropoff of O2

plateau of curve

can't saturate anymore...
almost all of hemes are occupied
even a huge change of partial pressure of O2, we barely affect % saturation
safety margin of error...see next notecard

safety margin of error:

we can still maintain oxygen delivery to tissue
ex: altitude (pressure goes down...concentration the same but particles more spread out...larger volume), mild altitude, blood doesn't notice

hookah (oxygen) bar...

gimmick!
can't add anymore O2 to lungs/body but will deplete CO2 concentrations...very dangerous for regulation (CO2 triggers breathing cycle and important for buffer system)

pneumonia

inflammation in lungs due to infection/fluid in lungs...
slower diffusion rates because molecules have larger distance to cross

emphysema

damage to lungs due to alveolar collapse...more CO2 means less room for O2

general roles of plateau and steep part of curve

plateau: protective...
steep part: allows for quick diffusion...essential

myoglobin

in muscle...one subunit of hemoglobin
allows some muscle fibers to store O2
myoglobin curve NOT sigmoid...
at low partial pressures of O2, myoglobin has higher affinity for O2 than hemoglobin...muscle GREAT at grabbing oxygen

Bohr Effect

changing the oxygen equilibrium curve
a DECREASE in the oxygen affinity of a respiratory pigment
has right and left shifts

RIGHT SHIFT

decreased affinity
hard to pick up, easy to drop off
-decreased oxygen loading in lungs
-increased oxygen unloading in tissue
Hb + O2 <------- HbO2

LEFT SHIFT

Increased affinity
easy to pick up, hard to drop off
-increased oxygen loading in lungs
-decreased oxygen unloading in tissue
Hb + O2 -------> HbO2

curve shifts RIGHT if...

pH goes down
CO2 goes up
temp goes up
HIGHER METABOLISM

curve shifts LEFT if...

pH goes up
CO2 goes down
temp goes down
LOWER METABOLISM

raising right arm rapidly...

right shift for the right arm (the one that's raised...)
-CO2 increases, H+ decreases, temp increases...right shift
left shift for the left arm (the one that's NOT raised)
-CO2 decreases, H+ increases, temp decreases...left shift

body does what with oxygen when one arm is raised?

drop off oxygen accordingly...

even with Bohr effect, saturation stays about the same...

hemoglobin about the same saturation...mess around with the steep part of the curve

why is too much O2 harmful?

slightly poisonous
free radicals
aging

oxygen equilibrium curve: ROOT effect (fish)

a decrease in the amount of O2 a respiratory pigment can bind at saturation
can shift saturation DOWN
advantage for fish: rapid unloading of gases into the swim bladder (altering pH can alter % saturation)

CARBON DIOXIDE

more than just waste!
partial pressures at sea level (full humidity)
-atmospheric: 30mmHg
-alveolar: 40mmHg
-venous: 45mmHg
note: old air not completely expelled...not as big of a [ ] gradient as O2...we tend to favor keeping CO2 around

carbon dioxide levels in plasma

3ml CO2/100 ml plasma (10x levels of O2 in plasma)
some also converted to carbonate
some carbon dioxide binds to hemoglobin
-affects O2 affinity to hemoglobin

Carbon Dioxide: Chloride Shift

the exchange of a chloride ion for bicarbonate across the red blood cell membrane
allows rxn to be driven in one direction or the other
enables the RBC to pick up and drop off high levels of CO2

the chloride shift has to do with...

CHARGE!
we only want current for neurons and muscle cells
without exchange, we generate current...bad!
bicarbonate out, chloride in!
bookkeeping of charge...

Chloride shift IN TISSUE

PREVENTS accumulation of bicarbonate in the cell...get it out!
Bring In Cl-
Increases CO2 PICKUP at tissues

Chloride shift IN LUNGS

brings bicarbonate BACK into cell to increase CO2 levels...kick out Cl-
increases CO2 DROPOFF...get it out of body through expiration

Carbon Monoxide

produced by incomplete combustion
competes with O2, binding to the heme group
nearly IRREVERSIBLE binding to hemoglobin

CO and O2 are approximately the same...

size

skin tone & carbon monoxide...extra credit!

low levels of O2: blue appearance...hemoglobin w/o much oxygen...dark red color refracted by skin = blue
when O2 binds to heme group...causes same bright red coloration since it's bound to hemoglobin...when refracted looks NORMAL...extremely dangerous!

won't let go like O2 does...so...

blood transfusions given because CO won't release from hemoglobin

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