November 3, 2023

Question 1

what is Transit time:

Answer 1

0.3 sec (usually) or .75 seconds (amount of time that blood goes from 40-100mmHg)

the amount of time blood spends interfacing with the alveoli (where gas exchange occurs)

Question 2

What amount of PaO2 fully saturates hemoglobin?

Answer 2

100mmHg

Question 3

Cardiac output can increase from 5L/min; can go up to ________L/min during exercise;

Answer 3

25L/min

flow is much faster

Question 4

During exercise, flow is faster so the transit time decreases, from .75 seconds to …….. for oxygen

Answer 4

to about 0.45 seconds

(still more than 0.3) so we still have excess time

Question 5

is CO2 a more diffusible gas than O2?Why?

Answer 5

yes

goes through membranes more easily

Question 6

how long does it take PaCO2 to go from 46mmHg to 40mmHg

Answer 6

Within 0.15 seconds, the PaCO2 goes from 46mmHg to 40mmHg (half the time as O2)

Question 7

In a moderately limited diffusion situation, does it takes longer for the PaO2 to get from 40 to 100mmHg

Answer 7

yes

Question 8

what are the two reasons why CO2 diffuses faster than oxygen

Answer 8

1. Not as big change in PaCO2(46-40 mmHg) compared to PaO2(40-100mmHg)
2. diffuses through membrane easier

Question 9

what test is used to diagnose underlying pathology

Answer 9

Exercise stress test is used to diagnose underlying pathology

i.e. riding a bicycle for a couple minutes

Question 10

is a stress test needed to determine underlying
conditions in a person with a severe diffusion limitation

Answer 10

no, because at rest there PO2 is already lower than 100mmHg

Question 11

is a stress test needed to determine underlying
conditions in a person with a moderate diffusion limitation

Answer 11

yes, because at rest there PO2 might be normal (100mmHg) but exercise can reveal a lower PO2 (compared to normal)

Question 12

what can happen as a result of diffusion limitations during exercise

Answer 12

hypoxemia (restrictive diseases)

Question 13

Does knowing that a person is hypoxemic mean that they’re also hypercapnic?

Answer 13

No, but the other way around is probably true

Question 14

what is a Restrictive Disease

Answer 14

Restrictive Disease: makes it harder to inflate the lung

Question 15

what is an obstructive disease

Answer 15

easy to inflate lung, hard to deflate lung

Question 16

what is Pulmonary Fibrosis (Restrictive Disease)

Answer 16

Pulmonary Fibrosis (Restrictive Disease)

Thickening of the alveolar membrane due to scar tissue (caused by infection, or inhalation of noxious chemicals)

Question 17

Can Pulmonary Fibrosis (Restrictive Disease) lead to increased diffusion time

Answer 17

yes

Question 18

Does pulmonary Fibrosis (Restrictive Disease) lead to increased or decreased lung compliance

Answer 18

Leads to decreased lung compliance (stiff lung, hard to open), which restricts airflow in, but no problem out

Question 19

Lung Compliance:

Answer 19

the ability of the lung to expand in response to a difference in pressure

Question 20

what is Pulmonary Edema

Answer 20

the accumulation of excess fluid in the lungs.

Question 21

how does Pulmonary Edema occur

Answer 21

1. Poor Left Ventricle function due to congestive heart failure or post-myocardial infarction (not injecting enough from the ventricle); forces fluid between alveoli and capillary which increases diffusion distance
2. Increased left atrial pressure

3.increase in pulmonary venous pressure

4. This forces fluid into the interstitial space (edema) from pulmonary capillaries causing an increased space between membranes and limits diffusion

5.More effort to inflate the lung (decreased lung compliance, laboured breathing:
dyspnea)

Question 22

what is a possible treatment for both Pulmonary Edema and Pulmonary Fibrosis

Answer 22

a moderately progressive program of physical activity

–>

improves LV function and respiratory muscle strength

Question 23

During exercise, there is an increase in free ADP and an increase in mitochondrial respiration this leads to……..

Answer 23

decrease in PvO2 and an increase in PvCO2 (production of Krebs and “extra” CO2)

We are using more O2 and giving up more CO2

Question 24

PaO2 is always maintained at _______ even during exercise

Answer 24

100mmHg (does not curve downwards like in the
graph)

page 107

Question 25

During exercise, despite the fact that PvO2 comes in at a lower pressure (20mmHg instead of 40mmHg), does it still reach 100mmHg in the same amount of time (0.3 seconds)

Answer 25

yes

during exercise, despite the fact that PvO2 comes in at a lower pressure (20mmHg instead of 40mmHg), it still reaches 100mmHg in the same amount of time (0.3 seconds)

check this by looking at PaO2 , it remains constant

page 107

Question 26

During exercise, despite the fact that PvCO2 starts at 46mmHg and continues to increase do we become hypercapnic

Answer 26

no, look at PaCO2, it remains constant at 40mmHg even during maximal exercise, therefore we don’t become hypercapnic

Question 27

why do highly trained elite endurance athletes sometimes produce hypoxemia (low O2) during exercise. why

Answer 27

A very high cardiac output

A higher than normal O2 extraction at the tissues

In-depth explanation: they have a transit time of about 0.25 seconds (which is lower than regular people of 0.45 seconds), because their flow is faster, because their cardiac output is faster. They also start at a lower PvO2 (about 10 mmHg), so their PvO2 has to increase a greater amount to get back up to 100mmHg compared to regular people.

That gap from 10mmHg to 100mmHg can be achieved, just not in 0.3 seconds

Summary:
-Start at a lower PvO2
-Have a shorter transit time

page 108

Question 28

O2 Transport is dependent on?

Answer 28

Partial Pressure of Oxygen (PO2)

Question 29

what are the two places O2 goes in the blood

Answer 29

1.Dissolved in plasma

2.Dissolved in plasma bound to Hb

Question 30

how many mls/100mls of blood per every mmHg of partial pressure

0.003mls/100mls of blood per every mmHg of partial pressure

Answer 30

0.003mls/100mls of blood per every mmHg of partial pressure

Question 31

what is Dissolved PaO2 at 100 mmHg

Answer 31

Dissolved:
➢ At PaO2 = 100 mmHg
➢ This means 0.3mls O2 /100mls of blood is dissolved

➢ “0.3 volumes %”

page 109

Question 32

what is Dissolved PaO2 at 700 mmHg

Answer 32

since 0.3 volume % = 100mmHg

2.1 volume % = 700mmHg

Question 33

how many mls of O2 can bind to Hemoglobin (Hb) when 100% fully saturated

Answer 33

1.34 mls of O2 when hemoglobin 100% fully saturated

Question 34

Males have: _____g of Hb/100mls of blood

Answer 34

16

Question 35

Females have: ______g of Hb/100 mls of blood

Answer 35

14

Question 36

if you go up to high altitude, and the lower PO2 produces less Hb saturation (say 50%), how many mls of O2 can 1 gram of Hb hold

Answer 36

1.34 mls = 100%

0.67 mls = 50%

Question 37

Calculate the total O2 carried by the blood at 100% Hb saturation and a PO2 of 100mmHg, when the Hb is 16g/100mls

Answer 37

answer on page 109

Question 38

true of false: the higher the PO2 the higher the % saturation of Hb

Answer 38

true

100% saturation of Hb = 100 mmHg PO2

Question 39

Solve Ryan’s problem (page 110)

Answer 39

Solve Ryan’s problem

➢ Hb = 12g/100mls
➢ PaO2 = 32mmHg (use this to find % saturation)
➢ % saturation = 0.63 (multiply this by 1.34)
➢ 0.63 x 1.34 = 0.8442 (multiple this by 12gHb/100mls)
➢ 10.1 vol%