DeCoursey Blood Gas Transport

Question 1

Colors that Hb can be and why

Answer 1

Oxygenated- Red
Deoxy- Blue
Carboxy-Hb(CO bound)- Cherry Red

Question 2

Describe shape of Hb
how binding sites interact
where it has the most ideal O2 affinity?

Answer 2

Tetramer with 4 O2 binding sites
Allosteric interaction
At or right above sea level

Question 3

What explains the sigmoid shape of Hb curve?

Answer 3

Coopertivity- after one O2 binds the affinity to O2 of the open sites increase and the stope becomes steeper

Question 4

Why is it flat at the top of the curve?

Answer 4

The Hb is mostly saturated with O2 already which is why there is little difference between PO2 of 80-130

Question 5

What determines capacity of blood? What is capacity

Answer 5

Solely determined by the amount of Hb. We are considering the amount of O2 blood COULD carry and since so little is dissolved then we only considered Hb.

Question 6

Equation for capacity of blood

Answer 6

{Hb} x 1.34 O2 capacity of 1gm

Question 7

What happens with O2 above PO2 of 100

Answer 7

Most of the Hb is saturated and any increase in O2 is directly proportional to an increase in dissolved O2

Question 8

Calculating dissvoled O2

Answer 8

Solubility of O2 (.003) x PP

Question 9

What is content?

It’s equation

Answer 9

The total amount of O2 in blood

Content= (So2 % Hb saturated) x O2 capacity + (solubility x PP)

We’re consider the Hb-bound + dissvoled O2

Question 10

What does a down/right shift mean of oxyHb curve?

Answer 10

Lower affinity to O2 (MAIN) so more released to the tissues so at the same PO2 more O2 is released

And in the lung slight decrease in the uptake by the blood

Question 11

What cause downright shift?

Answer 11

Decrease pH
Increase H+
Increase Temp
Increase CO2
Increase DPG

Question 12

How does DPG work>

Answer 12

It binds to Hb and It decreases O2 affinity to Hb

Question 13

What are the four types of hypoxia?

Answer 13

Hpoxic Hypxia
Anemic Hypoxia
Hypoperfusion hypoxia
Histotoxic hypoxia

Question 14

What happens in hypoxic hypoxia?

Causes?

Answer 14

Low alveolar O2 leads to Low arterial PO2. The tissue drops ebcause there is no driving force from arterial to tissue anymore.

Causes- high altitude, diffusion impairment
Increased FLow of O2 would be helpful

Question 15

What happens in anemic hypoxia?

Answer 15

The capacity of Blood isn’t enough because of the lack of Hb. PaO2 may be normal but the capacity is reduced so the tissues suffer.

As O2 lets off from capillary into the tissue the driving force decreases faster than normal.

increased O2 flow wouldn’t help because the capacity is low

Question 16

What happens in hypoperfusion hypoxia?

Answer 16

O2 pressure and capacity are normal. Tissues are deprived because of the slow movement of blood so the O2 is extracted before.

More so a circulatory problem than respiratory.

increased flow of O2 wont help

Question 17

What happens as cells move away from capillary?

Answer 17

The Po2 slowly drops the further the cell is.

So if a capillary starts with a lower than normal PO2 then it decreases as it reaches the cell and those cells are hypoxic. IF the cell is too far it won’t get O2 and those are anoxic.

Question 18

What happens in histotoxic hypoxia>

Answer 18

Metabolic poisions interfere with the use of O2 in mitochondrial respiration

Increaesd flow won’t help. Everything before capillaries is normal, everyhitng in venous is high.

Question 19

3 forms on CO transportation with percentages

Answer 19

1. Bicarbonate (HCO3) 65%
2. Dissolved 10%
3. Carbamino 5-10% of total but ~25% is transported

Question 20

What enzyme produces CO3-? Where and whats turnover rate>

Answer 20

CA-II
It’s in RBC but not in plasma.
Turnover rate of million/sec

Question 21

How can CO3- form? (2 ways)

Answer 21

Through CA-ii CO2 +H2O– H2CO3–> HCO3 +H in RBC

There is spintaneous formation in plasam as well but this is very slow

Question 22

Explain why cholride is higher in arterial than venous plasma and bicarbonate lower

Answer 22

1. In RBC HCO3 is formed very quickly and leaves the cell because of the large gradient it forms
2. Cl- enters the RBC to maintain neutrality (chloride shift)
3. So when you measure Cl in arterial its higher because in venous it is in the RBC

bicarbonate it higher in venous plasma

Question 23

Explain the affect of the H+ made with bicarbonate

Answer 23

1. It will probably slightly lower the pH

2. It will bind to Hb and protonate lower its affinity to O2 (right shift) increasing O2 to the tissues

Question 24

Explain the haldene affect

Answer 24

The curve is sensitive to the PO2. When we increase PO2 we decrease the ability to hold CO2.

Question 25

Why does haldene work at both ends>

Answer 25

At the lungs the high PO2 increase the release of CO2 and at the tissue the low PO2 increases the uptake

Question 26

What content of ocygen increases linearly as we increase PO2?

Answer 26

The amount in physical solution.

Total content follows the oxyhb curve.

Question 27

What happens to the curve in oxyHb in anemics and polycythemia?

Answer 27

the shape of the curve is the exact same because that’s simply telling how how much bind to Hb.

Question 28

Affects of CO on the oxyHb curve

Answer 28

1. Binds to the O2 sites and reducing the capacity to bind to O2
2. SEcond it causes an allosteric affect on O2 increasing its affinity to O2 and releasing less O2 to the tissues (LEFT SHIFT)

Question 29

Why does CO bind over O2

Answer 29

Hb has almost 200x the affinity to CO and binds tightly.