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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0
Q

Fx of hemoglobin

A

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

1
Q

2 methods for transporting O2 in the blood

A

1) dissolved in fluid phase of blood

2) O2 bound by Hb

2
Q

What produces Hb?

A

RBC as it’s forming

3
Q

How to calculate dissolved oxygen content

A

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

4
Q

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

A

Decreased binding

5
Q

Normal Hb bound O2 content

A

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

6
Q

What comprises “globin” region of Hb?

A

imidazole group

7
Q

Percent saturation of O2 =

A

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

(HbO2 bound/HbO2 capacity)*100

8
Q

greater PO2 –> binding ability of O2 on Hb

A

Increases. Oxygen saturation is an indicator of PO2

9
Q

P50

A

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

10
Q

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

A

H+, CO2, and temp

11
Q

increased temp –> Hb affinity for O2?

A

Decreased

12
Q

increased PCO2 –> Hb affinity for O2?

A

Decreased

13
Q

Where is Hb’s affinity for O2 highest?

A

lungs

14
Q

Where is Hb’s affinity for O2 lowest?

A

tissues (muscles)

15
Q

Where is affinity for protein-bound CO2 lowest?

A

lungs

16
Q

Fastest way to get rid of CO2 at the lung

A

dissolving CO2

17
Q

Total blood oxygen content =

A

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
Q

Volume of O2 extracted by the tissues =

A

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

19
Q

carbamino compounds fx

A

proteins that bind CO2

20
Q

3 ways to transport CO2

A

1) dissolved
2) protein bound
3) bicarbonate

21
Q

2 ways to transport O2

A

1) dissolved

2) protein bound

22
Q

What state must gas be in to enter alveolus?

A

Dissolved state

23
Q

carbonic anhydrase equation

A

CO2 + H2O H2CO3 HCO3- + H+

24
Q

How does CO2 get from tissue to alveolus?

A

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
Q

Why is oxygen binding curve sigmoid?

A

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

26
Q

How many O2 molecules can 1 Hb bind?

A

4 (1 on each heme group)

27
Q

What should partial pressure of alveolar air equal?

A

partial pressue of disssolved O2

28
Q

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

A

partial pressure of O2, temperature

29
Q

Acidosis

A

decrease in blood pH from normal range of 7.35-7.45

30
Q

Increased PCO2 –> O2 release to tissues?

A

increased

31
Q

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

A

increased

32
Q

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

A

decrease

33
Q

Where is 2,3-DPG produced?

A

muscles

34
Q

Normal Hb saturation

A

97%

35
Q

Normal arterial PCO2

A

40mmHg

36
Q

Haldane Effect

A

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
Q

Major form of CO2 storage in the blood

A

HCO3

38
Q

Importance of HCO3- in the blood

A

acts as pH buffer in blood

39
Q

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

A

body has stores of HCO3- outside the blood

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