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PHGY 210 > Respiration lecture 4 > Flashcards

Respiration lecture 4 Flashcards

1
Q

The amount of dissolved gas carried by the blood is directly proportional to… according to

A

partial pressure
Henry’s law

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2
Q

What amount of O2 is dissolved in the blood?

A

0,3 mL at a PO2 of 100 mmHg

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3
Q

What is O2 linearly proportional to?

A

the O2 dissolved in blood is linearly proportional to PO2

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4
Q

O2 consumption is much ___ than what can be supplied from the amount dissolved in the blood

A

more

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5
Q

What is the rate of consumption of O2 at rest?

A

300 mL O2/min

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6
Q

What allows blood to take up to 65 times as much O2 as plasma at PO2 of 100 mmHg?

A

hemoglobin

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7
Q

How much does hemoglobin constitute of the total weight of red blood cells?

A

1/3 of the RBC total weight

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8
Q

Why is Hb essential for the transport of O2 by blood?

A

because it combines rapidly and reversibly with O2

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9
Q

At PO2 of 100 mmHg, what is the percentage amount of O2 physically dissolved in the blood?

A

0.3 vol. %

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10
Q

At PO2, of 100 mmHg, what is the total amount of O2 bound to Hb?

A

19.5 vol. %

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11
Q

What is the total amount of O2 in arterial blood?

A

20 vol. %

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12
Q

Does the O2 that is bound to Hb contribute to the PO2 of the blood?

A

No

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13
Q

What O2 molecules are responsible for PO2?

A

the O2 dissolved in the blood

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14
Q

What does the PO2 of the plasma determine?

A

the amount of O2 that will be bound to Hb

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15
Q

What does the HbO2 dissociation curve determine?

A

the amount of O2 carried by Hb for a given PO2

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16
Q

When is the HbO2 dissociation curve flat? What levels?

A

At high values of PO2

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17
Q

When is the HbO2 dissociation curve steep?

A

At low levels of PO2

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18
Q

What happens to the amount of O2 bound to Hb at high values of PO2?

A

there is a constant high affinity between the Hb and O2

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19
Q

How much does PO2 have to drop in order for HbO2 to drop significantly?

A

Around 60 mmHg of PO2, there is a release of O2 (less bound to Hb)

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20
Q

What happens to Hb at high pressures?

A

it is saturated

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21
Q

What happens to Hb at low pressures? Why?

A

it is desaturated because O2 moves into the tissues with low O2 to supply their metabolism

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22
Q

What happens to HbO2 at low PO2?

A

it dissociates into Hb and O2 more readily than at high PO2

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23
Q

Why is there a significant drop in PO2 and %HbO2 at the tissue level?

A

because it’s where metabolic processes happen to match tissue O2 supply to tissue O2 need (O2 moves from the blood to the tissue in need)

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24
Q

As blood enters the tissue capillaries, plasma PO2 is ___ than interstitial fluid PO2

A

higher

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25
Q

O2 readily diffuses across the capillary membrane into the ____

A

interstitial fluid

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26
Q

What happens to plasma PO2 and O2 when O2 readily diffuses across the capillary membrane into the ISF?

A

plasma PO2 decreases
O2 diffuses out of the erythrocytes into the plasma

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27
Q

What happens to the HbO2 when the erythrocytes PO2 decreases?

A

it dissociates into Hb and O2

28
Q

After diffusing into the interstitial fluid, where does the O2 go?

A

into the cells

29
Q

What determines the affinity of Hb for O2?

A

the structure

30
Q

What increases the affinity of the second binding for O2?

A

the binding of the first O2

31
Q

Where is myoglobin found?

A

in skeletal muscles

32
Q

Myoglobin resembles Hb but binds only…

A

one O2

33
Q

What shape is the Hb O2 dissociation curve?

A

sigmoid

34
Q

What shape is the O2-myoglobin curve?

A

Hyperbolic

35
Q

When does myoglobin release its O2 in a O2-myoglobin curve?

A

when PO2 levels are very low (safety net)

36
Q

What does the total amount of O2 in the blood depend on?

A

Hb concentration

37
Q

How much is the normal amount of Hb in a person?

A

14g /100 ml

38
Q

How much Hb does someone who has anaemia have? Why?

A

10g / 100 ml
Even when saturated, the lower amount of Hb decreases O2 levels compared to the norm

39
Q

When does the Bohr Effect shift the HbO2 dissociation curve to the right?

A

If the blood CO2 increases
If body temperature increases
If blood pH decreases

40
Q

What does it mean when the HbO2 dissociation curve shifts to the right?

A

for a same PO2, there’s less affinity meaning that more O2 is released into working tissues

41
Q

When does the Bohr equation shift the HbO2 dissociation curve to the left?

A

If the blood CO2 decreases
If the body temperature decreases
If the blood pH increases

42
Q

What has an extremely high affinity for the O2 binding sites in hemoglobin?

A

Carbon monoxide (CO)

43
Q

What reduces the amount of O2 bound to hemoglobin?

A

if CO binds to the Hb

44
Q

What does CO do to the O2-hemoglobin curve?

A

It shifts the curve to the left and decreases the unloading of O2 to the tissue

45
Q

What are the 3 ways CO2 is carried in the blood?

A

Physically dissolved in the blood (10%)
Combined with Hb to form HbCO2 (11%)
As Bicarbonate (79%)

46
Q

Where does CO2 combine with Hb?

A

on the globin (not heme like O2)

47
Q

Why does CO2 combine with the globin portion and not the heme portion of Hb?

A

so that there is no competition for binding on Hb

48
Q

What does CO2 combine with to produce carbonic acid?

A

H2O

49
Q

What aids the diffusion of CO2 in the erythrocytes?

A

carbonic anhydrase

50
Q

What are the 2 formulas for bicarbonate?

A

CO2 + H2O –> H2CO3
H2CO3 –> HCO3- + H+

51
Q

All of the reactions involved with CO2 are…
Why?

A

reversible
We need the CO2 to be transported in the form of bicarbonate (formula to the right) but we also need the bicarbonate to transform into CO2 once it reaches the tissues (formula to the left)

52
Q

What happens to the production of HbCO2, HCO3, and H+ if the CO2 production increases?

A

More HbCO2
More HCO3
More H+

53
Q

What happens to HCO3 when blood PCO2 decreases?

A

it gets transformed into H2CO3 and further into CO2 and H2O, and HbCO2 generating Hb and CO2

In other words, HCO3 releases CO2 with the formula to the left

54
Q

What are the two reactions that happen when the blood PCO2 decreases?

A

H+ +HCO3- –>H2CO3
H2CO3 –> H2O + CO2

55
Q

Why is there a decrease in blood PCO2 when there is a net diffusion from the blood into the alveoli?

A

CO2 is exhaled through the alveoli because blood PCO2 is higher than the alveolar PCO2

56
Q

Hb free of O2 may combine with what?
Why?

A

H+
Hb is less acidic than HbO2 because Hb takes an H+

57
Q

What is the reaction of the addition of H+ to Hb?

A

H+ + HbO2 <–> HHb+O2

58
Q

What is the preferred way to transport CO2 in the body?

A

HCO3

59
Q

When Hb is free of O2 and combines with H+, it acts as a…

A

buffer

60
Q

What happens when Hb is present in the tissue capillaries?

A

It leaves O2 and takes up CO2

61
Q

When do you carry more CO2?

A

when your blood is deoxygenated

62
Q

Which kind of blood can carry more CO2 than arterial blood?

A

Venous blood

63
Q

What influences the CO2 dissociation curve by shifting it to the right?
Why?

A

the O2 saturation of blood
For a given PCO2, more CO2 is carried in the deoxygenated blood by pushing the equations to the right

64
Q

The Bohr effect helps …
The Haldane effect helps …

A

deliver oxygen to tissues
remove carbon dioxide from tissues.

65
Q

Bohr Effect
What happens?
Why?

A

Haemoglobin releases oxygen more easily in tissues with more carbon dioxide or acid (lower pH).

This helps oxygen reach where it’s needed most, like working muscles that produce more carbon dioxide and acid.

66
Q

Haldane Effect
What happens?
Why?

A

Hemoglobin binds more carbon dioxide when oxygen levels are lower, like in tissues. It releases carbon dioxide in the lungs where oxygen levels are high.

This helps remove CO₂ from tissues and get rid of it when you exhale.

PHGY 210 (8 decks)

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