respiration 3 Flashcards
what percent of oxygen is dissolved in the blood
2%(3ml/L;2mmol; 40mg)
what O2 in the blood is capable of diffusing
DIssolved O2
what is the resting O2 consumption
250ml/min
can dissolved O2 alone support basal metabolism
No(only can do 10%)
how much O2 is carried by hemoglobin
98% of O2
how much hemoglobin is found in the erythrocyte
250-280 million Hb for cell
how is hemoglobin designed
as a tettrameric molecule
what is hemoglobin made of
4 protein subunits
each with heme goup
+1 iron atom per heme
how much O2 can bind to one hemoglobin
4 O2’s
what is total O2 in blood a function of
PO2
Hb in blood
when is carrying capacity of the blood reached
when maximum HbO2% saturation = % of Hb in HbO2
what kind of binding does Hb exhibit to O2
cooperative binding
what else can bind to Hb to change its affinity to O2
binding of 2,3 DPG reduced Hb binding to O2
what is the plateua region of the Oxygen hemoglobin dissociation cuves
Loading phase
what is the steep region of the oxygen hb disociation curve
Unloading phase
what is O2 binding to Hb a function of
PO2
what is P50 on the oxygen-Hb dissociation curve
when half the Hb is saturated
does the amount of dissolved O2 change a lot as Po2 increases
No
why is it important to keep a high pool of dissolved O2 in the blood
Supply mitochondrial demand
does Po2 increase or decrease as it goes from ambient air to the mitochondira
decreases
can O2 bound to Hb diffuse
No, but is relasesd from Hb into the dissolved pool as PO2 falls
what does Hb do to help get O2 into blood
maintains Po2 gradient until Hb is saturated
what does an increase in Hb affinity for O2 do to the HB-OX binding curve
shifts it to the left
what does a decrease in Hb affinity for O2 do to the Hb-ox binding curve
shift curve to the right
what factors at the tissue tend to decrease Hb affinity for O2
metabolic activity
- increased temp (to right)
- increase CO2 (to the right)
- increased acidity (to the right)
- increase 2,3 diphosphoglycerate
what is the Bohr effect
increase in CO2 decreases Hb affinity for O2 when CO2 binds tot he Globin part of Hb (allosteric)
where does H bind to in Hb
binds to the globin part of Hb with allosteric affect
what does 2,3 Diphosphoglycerate come from
Glycolysis in erythrocytes
how does 2,3 DPG work
allosteric modulation
does the fetus or adult bind Hb better
fetus
why does fetal Hb bind O2 better than adult Hb
because a lower PO2 in the fetus
what makes fetal Hb different than adult Hb
subunits of fetal Hb are from different genes than postnatal/adult Hb
what are the amounts of Hb and O2 in the blood`
15g Hb and 20ml O2/100ml blood
what is anemia
fewer erythrocytes due to blood loss, reduced erythropoiesis, volume overload
how does the hematocrit change as Hb get lower per ml
Low hematocrit
does less Hb per ml of blood affect PO2, Hb saturation, or total O2 content
does no affect PO2 or Hb saturation
total O2 content though is reduced
how much greater does Hb have affinity for Co than O2`
200 times
how does .1% CO in air affect arterial PO2 and total O2
no change in PO2
50% drop of O2 in blood
what does CO do to the HB-O2 dissociation curve
moves it to the left (greater affinity for O2)
what are the ways CO2 is transported
dissolved (7%)
Bound to Hb (about 23%)
as HCO3 (70%)
does CO2 or O2 dissolve in plasma more
CO2 more
what is CO2 bound to hemoglobin
Carbaminohemoglobin
does CO2 compete with O2 binding
No, because CO2 binds to globin and O2 binds to heme
how does an increase in PCO2 change Hb affinity for CO2
increases affinity
what is the haldane effect
decreaseing PO2 increases Hb affinity (why CO2 binds in veins and not in arteries
what turns CO2 and H2O into HCO3 (carbonic acid)
carbonic anhydrase
where is carbonic anhydrase found
in the erythrocytes (not plasma)
how does HCO3 leave the Erythrocyte into the plasma
there is a HCO3/CL transporter in the erythrocyte
what does the transformation of CO2-> HCO3 do to the pH of the plasma
acifies the plasma
where do H+ bind in the hemeoglobin
binds to histine restidine
what does the affinity of H+ to hemoglobin depend on
PO2
oxygenated Hb affinity for H+ is high or low and why
high, because need to minimize the effect of HCO3 on pH
what buffers the H+ produced by the CA reaction
Hb
is there a large difference in pH of arteries and veins
No
what happens to H+ in the lungs
released from Hb and the CA reaction is reversed to create CO2
what does Hypoventilation do to blood pH
acidosis( increased PCO2-> increased H+)
what does hyperventilation do to blood pH
alkalosis ( decreased PCO2-> decreased H+)
