Transport Of Gases Flashcards

1
Q

What % of oxygen is carried bound to Hb from the alveoli to the tissues down pp

A

98% (2% is dissolved in plasma)

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2
Q

How many oxygens bind to the heme groups (fe and porphyrin)

A

4 = hb4o2

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3
Q

Which 4 things affect Hb saturation

A

Ph

Co2

Temp

23 BPG

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4
Q

What saturation do Hb have at high pp02 (100 in the alveoli)

A

97.5%

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5
Q

What happens to saturation at tissues with ppo2 which is low (40 at rest)

A

20-35% dissociation

The Hb is much less saturated at around 70% at low ppo2

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6
Q

Tissues which are respiring / exercise have lower than 40mmhg po2, what happens to dissociation/ saturation

A

85% of the oxygen becomes dissociated from Hb

Delivers o2 to the tissues

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7
Q

Why is ph / co2 high in the tissues which affects dissociation

A

Tissues are respiring producing co2 which is then converted to H to decrease ph

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8
Q

What happens if there is high pco2 eg at the tissues

A

Saturation decreases

Faster dissociation of o2 from the Hb

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9
Q

What would a lower ph (H+ presence due to co2) cause

A

Faster dissociation of o2 from Hb

ensures o2 to respiring tissues

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10
Q

Explain the steps of how co2 diffusion into rbc at high pco2 eg at tissues causes oxygen dissociation

A

Co2 presence will react with h20

Forms H2co3 (carbonic acid) - VIA CARBONIX ANHYDRASE

this splits into H+ and HCO

H+ binds to Hb to form HHb

This displaces o2 and o2 can diffuse into tissues

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11
Q

How does H binding to Hb cause oxygen dissociation

A

Hb becomes in the Taut state at high pco2 / H

This causes dissociation of oxygen to tissues

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12
Q

What is the effect of co2 and H called on oxygen dissociation

A

Bohr effect

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13
Q

What happens to the Hco3 produced by co2 diffusion into rbc at high pco2 levels

A

Diffuses into the blood/ plasma

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14
Q

When does temp increase

A

During exercise

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15
Q

How does temp affect dissociation

A

Increased temp due to exercise increases dissociation of o2 to tissues

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16
Q

How does 2,3 DPG affect dissociation

A

High 2,3 DPG causes faster dissociation

17
Q

How does dpg cause dissociation

A

Interacts with B chains and causes 02 dissociation

18
Q

When would high dpg be needed

A

In people with hypoxia / low o2

Increases their dissociation

Eg anemia, at high altitudes (low po2)

19
Q

How is Hbf different in dissociation

A

Much higher affinity/ saturation at every po2 than normal maternal dissociation curve

20
Q

What happens in anemia to cause low o2 levels

A

They have small / non working rbc with low o2 capacity

Even if saturated

Always much lower o2 content

21
Q

Does dpg cause dissociation in foetal hbf?

22
Q

How much of co2 is dissolved in plasma from tissues

23
Q

Other than dissolved co2, how else is co2 transported to alveoli

A

As HCO3 (70%)

Or

As Hb co2 (carbaminohaemoglobin) (23%)

24
Q

How is Hco3 produced and then transported to alveoli (bicarbonate)

A

Co2 diffuses into rbc from tissues

Reacts with h20 to form H2co3

Splits into H and Hco3

H binds onto the HHb whereas Hco3 diffuses into plasma to be transported

25
How is co2 later diffuses into alveoli
The 70% Hco3 binds with the H from HHb to form H2co3 (carbonic acid) H2co3 converts to co2 and water and co2 diffuses into alveoli Some co2 also from the dissociation of 23% hb co2 (carbamino haemoglobin) 7% diffused co2 diffuses straight to alveoli
26
At high pco2 what happens to carbonic anhydrase action
Converts the co2 and water to H2co3 forming Hco3 70%
27
Why would Hbco2 cause o2 dissociation as well as HHb would
Because it also favours the T state
28
Why does the production of co2 ie from HCO and H or the opposite reaction be slower in plasma than in RBC
No carbonic anhydrase to convert carbonic acid into co2 and water
29
What does CO bind to to stop o2 dissociation
Fe
30
How does CO stop oxygen dissociation
Shifts it to the Relaxed state (high saturation)
31
Why does co Hb have lower saturation
Rbc can’t pick up as much 02
32
How can CO poisoning be treated
Oxygen hyperbaric therapy
33
Why is NO binding to rbc important
Causes smooth muscle dilation to allow 02 dissociation to tissues
34
How does NO bind
Bind to oxygenated Or to Fe of deoxygenated rbc