Exam 3 -- Lecture 2 Flashcards
Hemoglobin is an _______ carrier
O2
hemoglobin is a _____mer
tetramer
Each monomer of hemoglobin contains a ______ and ______
heme
globin
What part of hemoglobin binds O2?
heme
What part of the heme binds O2?
Fe+2 (ferrous iron)
Does Fe2+ or Fe3+ bind O2?
Fe+2 (ferrous iron)
Is hemoglobin bound to O2 in relaxed or tense state?
relaxed (planar)
Is dissolved O2 sufficient to support the body?
no
What enzyme reverses the oxidation of Fe2+ to Fe3+ (Fe3+ cannot bind O2)?
methemoglobin reductase
What makes fetal Hb different than adult Hb?
has a gamma subunit instead of beta
VERY high affinity for O2
HbA1 a-c are different ________ forms of HbA1
glycosylated
What is the most common abnormal sickling Hb?
HbS
Deoxygenated HbS has low ____________ which causes it to create crystal structures that cause sickling of RBC
solubility
As more O2 binds to Hb does the affinity for O2 increase or decrease?
increase (hence sigmoidal shape)
Why does Hb-O2 curve eventually level off?
hemoglobin becomes saturated and begin to load off O2 into tissues
Why does Hb-O2 curve have sigmoidal shape?
positive cooperativity
as move O2 binds there is increased affinity
At higher P O2, more Hb molecules have transitioned from tensed to relaxed state there for a higher/lower affinity for O2
higher affinity
On a Hb-O2 disassociation curve, oxygen deprivation causes the curve the shift left or right?
right
On a Hb-O2 disassociation curve, lots of oxygen present causes the curve the shift left or right?
left
What 3 things can affect the shape of the Hb-O2 curve?
temperature
pH
Co2
** metabolism effects
Does Hb have a higher or lower affinity for O2 at low temperatures?
higher
Does Hb have a higher or lower affinity for O2 at high temperatures?
lower
Does Hb have a higher or lower affinity for O2 at low pH?
lower pH decreases oxygen affinity and promotes oxygen release
Does Hb have a higher or lower affinity for O2 at high CO2 levels?
higher CO2 = lower pH
- decreases oxygen affinity and promotes oxygen release
Does high CO2 stimulate release or uptake of O2?
release
What is the Bohr effect?
low pH and high CO2 levels cause Hb to have a decreased affinity for O2
**shift O2 disassociation curve to right
At low pH and high CO2 does Hb release or hold on to O2?
release
Is pH or CO2 the dominant controller of Hb affinity for O2?
pH
What is the purpose of 2,3-bisphosphoglycerate?
stabilizes the tense (deoxygenated) form of Hb, which reduces Hb’s affinity for oxygen.
* This increases the amount of free oxygen available for metabolically active tissues to use.
Which way does 2,3-bisphosphoglycerate? shift the Hb-O2 curve?
right (decrease O2 affinity)
Why does 2,3-bisphosphoglycerate bind easily to Hb?
its very negative and Hb is very positive
In the presence of low O2, anareobic glycolysis INCREASES/DECREASES, which means there is MORE/LESS 2,3-bisphosphoglycerate causing the RELEASE/UPTAKE of O2 by Hb.
increase anaerobic glycolysis
more 2,3-bisphosphoglycerate
release of O2
Is 2,3-bisphosphoglycerate more or less active when O2 levels are low?
more
If 2,3-bisphosphoglycerate has low affinity, then Hb’s affinity for O2 is HIGHER/LOWER
higher
What Hb has a low affinity for 2,3-BPG which makes Hb have very very high affinity for O2?
fetal Hb
What is the goal when moving CO2 in the body?
needs to be moved from systemic capillaries to pulmonary capillaries and out of the lungs
What are the 5 forms CO2 is found in the body?
dissolved
carbonic acid
bicarbonate (most common)
carbonate
bound to Hb
Can Hb bind O2 and CO2 and why?
yes; needs to offload O2 and pick up CO2 to carry it out of body
When CO2 binds to Hb, there is a release of H+ which RAISES/LOWERS Hb’s affinity for O2?
lowers
Increased H+ promotes RELEASE/UPTAKE of O2 by Hb?
release (decreased affinity)
high levels of bicarbonate (HCO3-) cause increased or decreased activity of carbonic anhydrase?
decreased (bicarbonate is the product) don’t need anymore product
What does the hamburger shift allow?
movement of bicarbonate out of cell so carbonic anhydrase can continue to convert CO2 into bicarbonate
Why is there cell swelling when CO2 is converted into bicarbonate via bicarbonate anhydrase?
H2O comes into cell because OH- (from H2O) is needed for carbonate anhydrase to convert CO2 into bicarbonate
What is the Haldane effect?
oxygenation of blood in the lungs displaces CO2 from Hb, increasing the removal of CO2
Low O2 promotes MORE/LESS CO2 binding to Hb in tissues.
more (to rid tissue of CO2)
** opposite in lungs
Low O2 promotes MORE/LESS CO2 binding to Hb in lungs.
less (allow CO2 the be taken up by alveoli and out of lungs)
In lungs does Hb have a low or high affinity for CO2 when CO2 levels are high?
low
In tissue does Hb have a low or high affinity for CO2 when CO2 levels are high?
high
What is Fick’s law?
gas movement across the alveolar-capillary membrane occurs through the process of diffusion
Gas uptake in the pulmonary system depends on what 2 things?
- phase of respiration
- diffusion barriers
During inspiration…
surface area INCREASES/DECREASES
increases
During inspiration…
barrier thickness INCREASES/DECREASES
decreases
During inspiration…
Po2 in alveoli RISES/FALLS and PCO2 RISES?FALLS
PO2 rises
PCOS falls
During inspiration…
PO2 INCREASES/DECREASES deeper into the lungs
decreases
During inspiration…
PO2 gradient INCREASES/DECREASES along the capillary
decreases
How is DL calculated in ficks law?
D1+D2+D3+…..
addition of all barriers together that must be passed
What does it mean if a gas is diffusion limited?
gases capillary pressure cannot reach gases alveolar pressure
PP of gas DOESNT REACH DIFFUSION EQUILLIBRIUM
If a gas is diffusion limited capillary pressure of gas ___ alveolar pressure of gas
capillary P < alveolar P
If a gas is perfusion limited capillary pressure of gas ___ alveolar pressure of gas
capillary P = alveolar P
What does it mean if a gas is perfusion limited?
concentration of gases on the two sides of the alveolo-capillary membrane becomes the same
PP of gas REACH DIFFUSION EQUILLIBRIUM
In perfusion limited gases the overall uptake of gas INCREASES/DECREASES with increased blood flow
increase
What is an example of a diffusion limited gas?
CO
carbon monoxide
What is an example of perfusion limited gas?
N2O
nitrous oxide
What makes CO a diffusion limited gas?
Hb has a very high affinity for CO so the partial pressure never gets very high because Hb picks CO up
What makes N2O a perfusion limited gas?
has a high diffusion capacity and doesn’t bind to Hb well so N2O levels rise quickly and easily reach equilibrium
Why will increase in cardiac output actually decrease uptake of diffusion limited gases?
less time for Hb to interact since blood is moving faster = less chance to uptake
How does increasing cardiac output increase to uptake perfusion limited gases even though there is less time for interactions to uptake the gas?
amount of nitrous oxide taken up in the pulmonary capillaries depends entirely on the rate of pulmonary blood flow, not on the diffusion characteristics of the alveolar-capillary membrane
increased flow = increased uptake even though it might take a little longer than normal it will still reach equilibrium at end of capilalry
Is O2 a diffusion or perfusion limited gas?
perfusion limited
Is CO2 a diffusion or perfusion limited gas?
perfusion limited
What are 4 example of the way an organisms acid-base balance is challenged?
- metabolism (CAC)
- ingestion
- lifestyle (exercise)
- pathology (vomiting, diabetes)
The pH of body fluids is tightly regulated through 3 primary mechanisms. What are they?
- buffering system
- respiratory system
- kidney system
What is the role of proton buffers?
minimize changes in pH
What symbol are proton buffers represented?
HA
What is the proton buffer equation?
(more acidic) HA <–> H+ + A- (more basic)
When you have a single buffer, maximum buffering power is at the pH that equals _____
pK
When you have multiple buffers, maximum buffering power is equal to …
sum of all buffering powers
What is the most common proton buffer system in respiration?
CO2/HCO3-
What is the proton buffer system equation of respiration?
CO2 + H2O <-carbonic anh.–> H2CO3 <—> H+ + HCO3-
concentration of HCO3- is regulated by what organ?
kidneys
concentration of CO2 is regulated by what organ?
lungs
CO2/HCO3- buffering complex has a low pK but it still works very well. Why?
bicarbonate concentration is VERY high (it can build up) while CO2 concentration isn’t because it cant build up due to being blown off by lungs
** fixed [ ]
Since CO2/HCO3- is a very powerful buffering system, when you add acid to it…
the acid immediately is neutralized while keeping solutions pH stable
What is an open buffering system?
buffering power can increase exponentially with pH
What is a closed buffering system?
buffering power reaches max at pK
Is the bicarbonate buffering system open or closed?
What about CO2?
open
closed
In the absence of other buffers, are you able to change the pH by changing the amount of HCO3- and CO2?
yes
In respiratory acidosis, there is an increase in P CO2, What are the affects on…
pH:
[HCO3-]:
P CO2:
direction of equation:
pH: decrease
[HCO3-]: increase
P CO2: increase
direction of equation: right
In respiratory alkalosis, there is an decrease in P CO2, What are the affects on…
pH:
[HCO3-]:
P CO2:
direction of equation:
pH: increase
[HCO3-]: decrease
P CO2: decrease
direction of equation: left
In metabolic acidosis, there is an increase in acids, What are the affects on…
pH:
[HCO3-]:
P CO2:
direction of equation:
pH: decrease
[HCO3-]: decrease
P CO2: none
direction of equation: left
- metabolic does has no change in CO2 b/c lung blows it off
In metabolic alkalosis, there is an increase in bases, What are the affects on…
pH:
[HCO3-]:
P CO2:
direction of equation:
pH: increase
[HCO3-]: increase
P CO2: none
direction of equation: right
- metabolic does has no change in CO2 b/c lung blows it off
What does a right shift in the Hb-O2 diassociation curve mean?
low O2 saturation
Carbamylated Hb releases ______
H+
Is CO2 levels higher in systemic or pulmonary capillaries and why?
systemic because high CO2 promotes Hb to pick it up and carry away from tissue
Is the CO2/HCO3 buffering system have a good pK?
No
very low
should be 7.4
