Physiology 40: Transport Of Oxygen & Carbon Dioxide In Blood & Other Tissues

Front 1

For oxygen to enter the pulmonary capillary, pO2 must be (lower or higher) in the alveoli?

Back 1

higher. oxygen will go from high to low. 104 in alveoli, 40 in the pulmonary capillary

Front 2

What is the pO2 in the alveoli before it enters the blood?

Back 2

104 mmHg

Front 3

What is the pO2 in the pulmonary artery before it is oxygenated?

Back 3

40 mmHg

Front 4

What is the pO2 in the left atrium?

Back 4

95 mmHg, drops from 104 due to deoxygenated bronchial vein drainage in

Front 5

What is the pO2 in the pulmonary vein?

Back 5

104 mmHg

Front 6

How come, during exercise, we can still oxygenate blood appropriately?

Back 6

increased ventilation/perfusion at lung apex (zone 2 to zone 3 circulation) and blood usually stays in the pulmonary capillaries 3x longer than it needs to, so even with increased flow it is still oxygenated

Front 7

interstitial fluid pO2 of a cell waiting to receive oxygen from a RBC

Back 7

40 mmHg

Front 8

Why MUST pO2 stay above 40 mmHg?

Back 8

oxygen must be able to leave the RBC at the interstitial fluid of the cell. if it is below 40, it will take more oxygen out of the cell

Front 9

If cells are using more oxygen for metabolism, we expect a (lower or higher) pO2 in the cell?

Back 9

lower, they are using more of it

Front 10

What 2 factors determine tissue pO2?

Back 10

rate of metabolism and rate of O2 delivery

Front 11

Average tissue pO2 (inside cell)

Back 11

23 mmHg on average (ranges from 5-40)

Front 12

Explain what makes a high safety factor in tissue cells.

Back 12

They have an average pO2 of 23 mmHg but only need around 1-3 mmHg

Front 13

Why doesn't carbon dioxide need large gradients to move in and out of cells/tissues?

Back 13

it diffuses 20x faster than oxygen

Front 14

pCO2 in the cell after O2 metabolism

Back 14

46 mmHg

Front 15

pCO2 in the interstial fluid before being taken into the veinous RBC

Back 15

45 mmHg

Front 16

Veinous pCO2

Back 16

45 mmHg

Front 17

Alveolar pCO2 before CO2 is removed from RBC

Back 17

40 mmHg

Front 18

Arterial pCO2

Back 18

40 mmHg

Front 19

Fun fact: Most CO2 is diffused out of the pulmonary artery in the first third of its time

Back 19

This is similar to oxygen's rate, except oxygen is going in the reverse direction

Front 20

Increased cellular metabolism leads to (increased or decreased) interstitial pCO2?

Back 20

increased. CO2 is the product of oxygen metabolism

Front 21

Increased blood flow leads to (increased or decreased) interstitial pCO2?

Back 21

decreased. faster moving blood takes CO2 out of interstitial fluid faster

Front 22

decreased pO2 in the blood signals hemoglobin to ...

Back 22

release O2

Front 23

What is hemoglobin oxygen saturation in veins?

Back 23

75%

Front 24

What % volume of blood is occupied by oxygen?

Back 24

20% = (15HB/100mL blood)(1.34 mL O2/1HB) = 20ml O2/100mL = 20%

Front 25

Normally, what percent volume of oxygen is released into tissues?

Back 25

5% (out of 20%)

Front 26

During exercise, what percent volume of oxygen is released into tissues?

Back 26

15% (out of 20%)

Front 27

A 75% pulse ox, as seen in veinous blood, refers to what pO2?

Back 27

40 mmHg

Front 28

Why can't pO2 rise above 40 mmHg in tissue?

Back 28

then pO2 in the interstitial fluid will rise and O2 will not go into interstitial fluid from the arteries.

Front 29

What 2 factors allow us to give adequate blood supply during exercise?

Back 29

Increased blood flow (more capillaries open) and steep slope of dissociation curve that sifts to the right

Front 30

Why doesn't tissue pO2 decrease as we increase in altitude, where there is a lower pO2 in the air?

Back 30

the flat part of the Hb dissociation curve allows us to decrease pO2 in the air and still keep a high oxygen saturation.

Front 31

Why doesn't tissue pO2 increase as we go underwater, where there is a higher atmospheric pO2?

Back 31

We are already at 97% saturation, and it can't really go much higher anyways

Front 32

What is the Bohr effect?

Back 32

occurs in tissue to ease O2 delivery. Hb dissociation curve shifts right

Front 33

What causes the Bohr effect (Hb curve shifting to the right)?

Back 33

increased temperature, acidity, CO2, BPG

Front 34

Why does the Bohr effect work?

Back 34

increase in CO2 from working tissues (e.g. during exercise) causes increase in H+

Front 35

The shift of the Hb dissociation curve to the right is seen where in the body, under normal conditions?

Back 35

All systemic tissues so oxygen leaves hemoglobin better

Front 36

The shift of the Hb dissociation curve to the left is seen where in the body, under normal conditions?

Back 36

in the lungs so oxygen binds hemoglobin better

Front 37

BPG increases during what condition?

Back 37

hypoxia or exercise

Front 38

What is the limiting factor in cell metabolism?

Back 38

ADP production, there is an excess of O2

Front 39

Assuming pO2 > 1mmHg, if we have .5 [normal ADP], the rate of metabolism will be? (in relation to normal)

Back 39

.5 of normal

Front 40

Increased distance between a cell and its blood vessel, as seen in pathology, will lead to decreased diffusion. These cells are called _______

Back 40

diffusion limited

Front 41

In pathology where blood flow falls to 0, these cells are no called _______

Back 41

blood flow limited

Front 42

Why does such a small amount of Carbon monoxide lead to death? (just .6 mmHg is toxic)

Back 42

It binds to Hemoglobin 250x more powerful than oxygen and out competes it

Front 43

Why is carbon monoxide such a dangerous gas?

Back 43

very strong binder of hemoglobin (250x oxygen), has no affect on pO2 or pCO2 levels in the blood so there is no respiratory compensation or even awareness

Front 44

How do we treat carbon monoxide poisoning?

Back 44

Give VERY high levels of O2 to try to out compete Carbon monoxide or give a LITTLE CO2 to stimulate hyperventilation

Front 45

What % of CO2 is dissolved in the blood?

Back 45

7%

Front 46

How does bicarbonate exit the RBC?

Back 46

exchange with Cl- through bicarbonate chloride carrier protein

Front 47

What is acetazolamide?

Back 47

carbonic anhydrase inhibitor, causes acidosis, but can be used to treat alkalosis

Front 48

What is the Haldane effect?

Back 48

binding of O2 to hemoglobin facilitates the release of CO2 from hemoglobin

Front 49

Which is greater in promoting transportation, the Bohr effect on Oxygen transport or the Haldane effect on carbon dioxide transport?

Back 49

Haldane

Front 50

How does the Haldane affect increase CO2 removal from hemoglobin? 2 ways

Back 50

displaces CO2 on the carbaminohemoglobin and increasing acidity of Hb causing it to dissociate a proton (leads to CO2 formation via bicarbonate pathway)

Front 51

Haldane affect makes CO2 dissociation how much more effective?

Back 51

2x more effective

Front 52

We exhale what percentage of CO2 in the blood?

Back 52

82%

Front 53

respiratory exchange ratio =

Back 53

rate CO2 out / rate O2 in

Front 54

If we use only carbohydrates for energy, our respiratory exhange ratio should equal ...

Back 54

1

Front 55

If we use only fats for energy, our respiratory exhange ratio should equal ...

Back 55

.7

Front 56

Which causes a higher respiratory exchange ratio? Using only fats for energy or using only carbohydrates?

Back 56

carbohydrates. The product of Carbohydrate metabolism is CO2, so we exhale more CO2, so R increases

Front 57

Which causes a lower respiratory exchange ratio? Using only fats for energy or using only carbohydrates?

Back 57

fats. the product of fat break down is more water than CO2, so there is less CO2 than if we only ate CO2 = lower R value (.7)

Front 58

What is the respiratory ratio in a normal person eating fats and carbohydrates?

Back 58

0.825

Front 59

Oxygen poisoning is when there is a high pO2 where?

Back 59

in the blood plasma (not Hb)

Front 60

Why is only 20% of CO2 bound to Hb?

Back 60

the rest is dissolved as bicarbonate