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Physio > Lecture 4 Transport of O2 and Co2 in blood > Flashcards

Lecture 4 Transport of O2 and Co2 in blood Flashcards

1
Q

how far through a capillary does co2 and 02 exchange occur?

A

1/3rd of the way.

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2
Q

during excersize does our v/q increase or decrease and in what location?

A

it increases in the apexes

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3
Q

what x-fold increase can occur in oxygenation during exercise?

A

20 fold increase

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4
Q

when we inhale, po4 goes from 40 to 104, and why does it drop to 95 in systemic system?

A

because the newly o2’d blood mixes with pulmonary shunt blood (areas where gas exchange did not occur)

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5
Q

When 95mmHg po2 reaches capillary tissues, how much is already in the interstium?

A

40mm po2

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6
Q

how much po2 is actually inside a cell (while interstitial is 40)?

A

23 mmhg po2

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7
Q

If you increase o2 consumption by 4, how will blood flow compensate for the ability of 02 to enter tissues?

A

you will need a higher blood flow to achieve the same po2 diffusion concentrations

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8
Q

what happens if you bring normal metabolic o2 consumption to 1/4 strength?

A

a much lower blood flow will drive a high po2 pressure into the tissues, and fluid will accumulate

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9
Q

what is the MAX and MIN po2 concentration a cell has?

A

5 - 40 mmhg

23 average

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10
Q

how much po2 do cells really need to function?

A

1-3 po2

really depends on metabolism

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11
Q

what is the average intracellular pco2?

A

46 pc02

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12
Q

why dont we need higher partial pressures of co2?

A

Co2 has higher solubility? so does not need a high driving force to diffuse

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13
Q

what is the range of pco2 between arterial and venous ends?

A

45 arterial, 40 venous pco2

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14
Q

What are the two huge safety factors in the pulmonary o2 and co2 exchange process that keeps the system from getting overloaded?

A
  1. Gas exchange occurs in first 1/3 of the distance of the capillary
  2. The time RBC’s are in the oxygen/co2 exchange system is 1/3 of total time in the body.
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15
Q

True of false, in the most intense exersize, there may be some blood cells that made it through the pulmonary capillary system without being oxygenated?

A

False (flow is adjuste at all times to match o2/co2 demands)

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16
Q

If blood flow to tissues is dropped by 4 (1/4th normal), upto how much pco2 can accumulate in the tissues?

A

60mhg

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17
Q

In the opposite direction, if blood flow is doubled 6 fold, pco2 will decrease to what number?

A

40mmhg

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18
Q

in normal blood flow, will metabolic rate increase or decrease to make pco2 40mmhg

A

decrease (less co2 output)

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19
Q

in normal blood flow, will metabolic rate increase or decrease to cause pco2 to elevate significantly

A

increase (more co2 waste as a result of increased cell metabolism)

20
Q

what percentage of o2 travels in the dissolved form, compared to whats bound to hemoglobin?

A

3%

97% is bound to hemoglobin

21
Q

what % of hemoglobin is saturated in arterial and venous blood?

A

97% arterial

75% venous

22
Q

the percent of maximum oxygen carrying capacity is called?

A

volume percentage

23
Q

the % of blood that donates its oxygen to the tissues is called

A

utilizaton coefficient

24
Q

upon entering tissues, the partial pressure of o2 drops, detachment from hemoglobin is slow or rapid

A

Rapid

25
Q

at normal metabolic rates, we are only donating what % of hemoglobin bound o2 to the tissues?

A

25% (huge safety factor here)

26
Q

what happens if you hold your breath, how is o2 still getting to tissues?

A

you only donated 25% at first go around, so theres more to spare if suddenly alveolar oxygen drops

27
Q

what tissue has the highest affinity for oxygen?

A

muscle

skin not so much

28
Q

oxygen will not depart from hemoglobin diffuse into tissues if tissue po2 is already above what value?

A

40mmhg (they have to really need it to get it, plus dissocation of hemoglobin po2 is high if surround concentrations of o2 are low)

29
Q

what two problems can the buffering ability of hemoglobin prevent?

A

oxidative stress

hypoxia

30
Q

hemoglobins can receive oxygen from the alveoli (90% saturation), even if the alveoli po2 is only what value?

A

60mmhg (it picks it up with ease in the lungs if they dont have much, can donate it with extra ease to areas with really low po2 concentrations. (the highly metabolic areas) )

31
Q

What 4 extracellular factors shift the dissociation curve to the right (more ease of dissociation at lower po2 values)

A

Increase H+ ion concentration (lower ph)
Increase Co2
Increased Body Temp
Increased BPG

32
Q

What does BPG do?

A

It allosterically binds to more deoxygenated hemoglobins, promotes dissociation of o2 from hemoglobin and increasing the usefulness of remaining bound o2

33
Q

What will hemoglobin / o2 assocation do in alkaline states?

A

recombine, causing lack of o2 to tissues (hypoxia)

34
Q

What toxin will cause oxygen to bind to hemoglobin with very high affinity and cause hypoxia? (Alkaline shift to the left)

A

CO

35
Q

Cells can become hypoxic under what 2 endogenous conditions?

A

They are too far away from capillaries (>50 micrometers away)
Blood flow is diminished (<1 p02 mmhg)

36
Q

Why would deep sea diving cause oxygen to become a toxin?

A

Diving pressure would cause o2 to exist in a dissolved state, and also damage endothelial cells and RBC’s

37
Q

What % of o2 is normally dissolved in the bloodstream?

A

3% (diving or positive pressure breathing will increase this)

38
Q

What do we call the molecule of carbon dioxide bound to hemoglobin?

A

Carbaminohemoglobin

39
Q

As co2 transports enters the RBC, some is bound as carbaminohemoglobin (23%), what % of co2 is attached to bicarbonate?

A

70%

40
Q

What is the pathway for the remaining 70% that does not bind with hemoglobin?

A

Co2 enters and combines with H20 to form H2co3 (via carbonic anhydrase).
The Carboxylic acid dissociates into H+ and Hco3-.
Bicarb leaves the cell to buffer the blood and the H+ ion binds to hemoglobin (HHgb).

41
Q

What part of that co2 pathway entering the RBC lowers the heme-o2 affinity, causing oxygen to release into tissue?

A

The hydrogen ions attaching to hemoglobins (HHb)

42
Q

When bicarb leaves the RBC to buffer the blood, what does it exchange with to maintain electrical neutrality within the RBC?

A

Chloride

higher in venous blood b/c it needs to be ready for when blood hits the lungs, and Chloride needs to enter the cell

43
Q

We only mentioned the 70% of Co2 that binds with H20, and the 23% that binds directly with Hemoglobin…wheres the rest?

A

Dissolved in the bloodstream (7%)

44
Q

What is the “effect” of co2 being responsible for driving oxygen out of the RBC to the tissues?

A

The Bohr Effect

45
Q

What “effect” is responsible for oxygens ability to drive co2 out of the RBC in the lungs

A

The Haldane effect

Physio (11 decks)

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