PULMONARY 07: GAS TRANSPORT

Question 1

Oxygen is carried in what 2 forms:

Answer 1

Dissolved and bound to hemoglobin

Question 2

Define PAO2

Answer 2

Alveolar partial pressure of oxygen

Question 3

Define PaO2

Answer 3

Arterial partial pressure of oxygen - DISSOLVED

Question 4

Define SaO2

Answer 4

Oxyhemoglobin or hemoglobin saturation - percentage of hemoglobin sites with oxyge nbound

This is dictated by PaO2 and PvO2

SpO2 is also called “peripheral” or “pulse” SO2

Question 5

Define CaO2

Answer 5

Oxygen content, oxygen concentration - total oxygen in the blood per unit of volume (dissolved + oxyhemoglobin)

Question 6

1mmHg of pO2 translates to 3uL O2 / 100mL of blood. That means that for the normal 100mmHg pO2, how much is in the blood? What does this mean for our oxygen needs vs what dissolves?

Answer 6

0.3mL / 100mL

The dissolved oxygen isn’t enough

Question 7

What type of Hgb is most common in adults

Answer 7

HbA

Question 8

Two states of hemoglobin molecularly speaking

Answer 8

Tense and relaxed state

Tense - low affinity
Relaxed - high affinity

Question 9

binding of oxygen to hemoglobin does what to the state of hemoglobin

Answer 9

Increases amount of hemoglobin in relaxed state

Question 10

At pressures of oxygen below 60mmHg, how is this affecting hemoglobin?

Answer 10

Small changes in oxygen pressure lead to a release of a huge amount of oxygen - faciliates release to organs/cells, but you don’t want this to be where the pressure of oxygen in the lungs is

Question 11

A leftward shift in the hemoglobin - oxygen curve indicates what

Answer 11

More Hemoglobin-o2 binding

Question 12

a rightward shift in the oxyhemoglobin dissociation cure indicates what?

Answer 12

Less hemoglobin oxygen binding

Question 13

The point at which 1/2 hemoglobin is saturated is called what?

Answer 13

P50

Question 14

Things that shift the oxyhemoglobin dissociation curve (4)

Answer 14

Temp
CO2
2,3 DPG
pH

Question 15

For most factors, as factor X increases, hemoglobin binding to oxygen (increases/decreases)

Answer 15

Decreases

For the case of pH we’re thinking of it as concentration of protons (because this would actually be a decrease in pH)

Question 16

As termperature increases, the oxyhemoglobin curve shifts what direction

Answer 16

Right

Question 17

As co2 increases, what is the effect on the curve and how is it reacting with hemoglobin?

Answer 17

Rightward shift
It binds to amino termini (not the same place as oxygen binding)
Happens normally in systemic capillaries

Question 18

Bohr effect

Answer 18

High CO2 leads to decreased pH; respiratory acidosis decreases O2 affinity - combination of CO and pH significantly changes binding curve shift

Question 19

How does increasing 2,3 dpg affect oxyhemoglobin binding curve?

Answer 19

Rightward shift

It preferentially binds to deoxyhemoglobin and allosterically decreases affinity for O2

Question 20

How does CO affect binding of O2 to hemoglobin

Answer 20

Dramatic INCREASE; hemoglobin has a WAY higher affinity for O2 so we can’t let go of it; however, CO also competitively binds for the same pocket, so you get less O2 binding overall

Therefore there’s less oxygen to begin with, and we can’t let go of what we’re carrying

Question 21

What are 3 respiratory reasons being in a burning building is bad?

Answer 21

Carbon monoxide fucking with oxyhemoglobin curve and oxygen being carried
Fire burns O2, so there’s low O2 around
The smoke inhalation is going to deposit particles and block airways

Question 22

Sickle cell Hemoglobin is denoted as what

Answer 22

HbS

Question 23

What is the problem molecularly speaking with HbS?

Answer 23

Under normal conditions it’s normal. But in low O2, such as in tissues, some HbS converts into a crystalizing structure which is permanent and fucks with the shape of the RBC. The more the RBC’s ccle, the more they crystalize out of solution and make weird shapes.

Question 24

What is Hb A1C

Answer 24

This is a standard blood test to look for diabetes. If you have high blood glucose, you get high levels of glucose-6-phosphate. This can glycosylate hemoglobin. The glycosylation itself is not pathalogical NECESSARIY, but we know that erythrocytes go in and out of cycle ~120 days ; therefore, you have a long term average readout for someone’s blood glucose level in this way

Question 25

1g of Hb can bind how many mls of O2

Answer 25

1.34mL

Question 26

To calculate oxygen content in arterial blood, we multiply what two things together?

Answer 26

O2 capacity of hemoglobin, and SO2 (oxygen saturation)

You don’t add what’s dissolved, it’s negligible

Question 27

How much oxygen is extracted at tissues

Answer 27

4mL/100mL blood

Question 28

If you have an anemic patient, how does this affect oxygen content?

Answer 28

For the same oxygen saturation, there is less total oxygen that can be used by the body

Question 29

3 main ways carbon dioxide is transported in the blood

Answer 29

Dissolved
Bicarbonate
Carbamino compounds

Question 30

What is the form MOST carbon dioxide is carried in the blood

Answer 30

bicarbonate

Question 31

per 1mmHg PCO2, there is 0.067mL CO2/100mL in the blood. What does this mean about CO2 dissolving vs O2?

Answer 31

CO2 dissolves about 20x more readily than O2

Question 32

CO2 conversion to bicarbonate PRIMARILY occurs where?

Answer 32

Erythrocytes using carbonic anhydrase (this would happen naturally in plasma, but VERY slow)

Question 33

Most important protein carbon dioxide will bind to as a carbamino compound is what/

Answer 33

Hemoglobin

Question 34

Hemoglobin can bind O2, or CO2 more?

Answer 34

CO2

This is not competitive, but stoichiometric (4co2/Hb)

Question 35

Haldane effect

Answer 35

Unload more CO2 as we get to lungs in oxygen rich environment; bind CO2 in tissues with CO2 rich environment

Question 36

Haldane vs Bohr

Answer 36

Haldane: Effect of O2 on Hb to increase/decrease binding to CO2

Bohr: Effect of CO2 on Hb to increase/decrease binding to O2

Therefore
Haldane: Important when considering CO2 unloading in lungs
Bohr: Important when understanding O2 unloading in tissues