Respiration Lecture 09: Transport of Gas by the Blood Flashcards Preview

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Flashcards in Respiration Lecture 09: Transport of Gas by the Blood Deck (40):
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2 methods for transporting O2 in the blood

1) dissolved in fluid phase of blood
2) O2 bound by Hb

1

Fx of hemoglobin

Binds O2 from alveolus and delivers to tissue. Normally at 1.39 ml O2/g Hb. Comes by alveolus in venous blood, leaves to tissues in arterial blood

2

What produces Hb?

RBC as it's forming

3

How to calculate dissolved oxygen content

oxygen content = oxygen solubility X arterial partial pressure of O2 (PaO2)
cO2 =

4

How does increased H+ affect O2 ability to bind Hb?

Decreased binding

5

Normal Hb bound O2 content

1.39 ml O2/gm Hb or 20.85 ml O2/dL blood

6

What comprises "globin" region of Hb?

imidazole group

7

Percent saturation of O2 =

ratio of O2 bound Hb to the total Hb binding capacity times 100

(HbO2 bound/HbO2 capacity)*100

8

greater PO2 --> binding ability of O2 on Hb

Increases. Oxygen saturation is an indicator of PO2

9

P50

partial pressure of O2 that can bind 50% of Hb (a measure of the affinity of Hb for O2)

10

ability of Hb to bind O2 is fx of 3 things:

H+, CO2, and temp

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increased temp --> Hb affinity for O2?

Decreased

12

increased PCO2 --> Hb affinity for O2?

Decreased

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Where is Hb's affinity for O2 highest?

lungs

14

Where is Hb's affinity for O2 lowest?

tissues (muscles)

15

Where is affinity for protein-bound CO2 lowest?

lungs

16

Fastest way to get rid of CO2 at the lung

dissolving CO2

17

Total blood oxygen content =

Hb Bound O2 + Dissolved O2
=(1.39 * Hb * %sat) + (0.003 * PO2)
Hb will = 15 unless told otherwise

Do For BOTH arterial and venous blood and add together to get total content

18

Volume of O2 extracted by the tissues =

arterial content of O2 (CaO2) - venous content of O2 (CvO2) (oxygen extraction driven by mitochondria)

19

carbamino compounds fx

proteins that bind CO2

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3 ways to transport CO2

1) dissolved
2) protein bound
3) bicarbonate

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2 ways to transport O2

1) dissolved
2) protein bound

22

What state must gas be in to enter alveolus?

Dissolved state

23

carbonic anhydrase equation

CO2 + H2O H2CO3 HCO3- + H+

24

How does CO2 get from tissue to alveolus?

CO2 leaves tissue, dissolved and enters RBC where it is converted to HCO3- by carbonic anydrase and released again. Near alvelus, HCO3- enters RBC, transformed back into dissolved CO2 and transferred to alveolus.

25

Why is oxygen binding curve sigmoid?

Hard to bind sites 1 and 4 on Hb, easy to bind sites 2 and 3

26

How many O2 molecules can 1 Hb bind?

4 (1 on each heme group)

27

What should partial pressure of alveolar air equal?

partial pressue of disssolved O2

28

What 2 things determine volume of O2 dissolved in the blood?

partial pressure of O2, temperature

29

Acidosis

decrease in blood pH from normal range of 7.35-7.45

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Increased PCO2 --> O2 release to tissues?

increased

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decrease in blood PCO2 --> loading of O2 in alveoli?

increased

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increased 2,3-DPG --> Hb affinity for O2

decrease

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Where is 2,3-DPG produced?

muscles

34

Normal Hb saturation

97%

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Normal arterial PCO2

40mmHg

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Haldane Effect

the formation of carbamino compounds weakens the Hb affinity for O2 in the tissue and aids in unloading of O2. In the lung, PO2 antagonizes the carbamino formation and aids the unloading of CO2. Facilitates CO2 off loading and produces a physiological dissociation curve that is steeper than for the arterial or venous curves alone

37

Major form of CO2 storage in the blood

HCO3

38

Importance of HCO3- in the blood

acts as pH buffer in blood

39

Why will cessation of ventilation have a greater effect on O2 than CO2?

body has stores of HCO3- outside the blood

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