Carbon Dioxide In Blood And Chemical Control Of Breathing Flashcards Preview

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Flashcards in Carbon Dioxide In Blood And Chemical Control Of Breathing Deck (43)
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1

How much more carbon dioxide is there in arterial blood than oxygen?

2.5 x

2

What is the total content of carbon dioxide in arterial blood?

21 mmol/L

3

What is the total content of oxygen in arterial blood?

8.9 mmol/L

4

What range must we keep arterial blood pH between?

7.35 - 7.45

5

How do we work out the concentration of carbon dioxide dissolved?

Solubility of CO2 x partial pressure CO2

6

What is the solubility factor of carbon dioxide at 37'C?

0.23 mmol/L/kPa

7

How does carbon dioxide reaction with water?

CO2 and water reacts to form carbonic acid (H2CO3)
Very quickly dissociates to form H+ and HCO3-
Reversible reaction

8

What does the pH of the blood depend on?

CO2 dissolved that reacts to form H+

9

What is the partial pressure of CO2 in the alveoli determined by?

Rate of breathing

10

What happens to the partial pressure of CO2 if we hyperventilate?

Decreases

11

What happens to the partial pressure of CO2 if we hypoventilate?

PCO2 increases

12

What is the normal concentration of HCO3- in the plasma?

25 mmol/L

13

What is the cation mostly associated with HCO3-?

Na+

14

How does a high HCO3- affect CO2?

Pushes the equation to the left
Prevents nearly all of the CO2 from reaction
Therefore plasma is alkaline

15

What is the equation for calculating pH from pCO2 and HCO3-?

Henderson-Hasselbach Equation

pH = pK + log ([HCO3-] / (pCO2 x 0.23) )

pK = constant 6.1 at body temperature

16

What is the normal ratio of HCO3- to CO2?

20:1

17

Which enzyme speeds up the reaction of CO2 and water?

Carbonic anhydrase (CA)
In RBCs

18

What happens to the products of the CO2 reaction in a RBC?

H+ ions bind to negatively charged Hb
Chloride bicarbonate exchanger (antiporter) transports HCO3- out of RBCs

19

Where is the concentration of HCO3- in the body controlled?

Kidneys

20

What happens when the body produces acids?

React with HCO3- to produce CO2
Removed via breathing

21

What happens when venous blood arrives at the lungs?

Hb picks up oxygen - goes into R state
Hb gives up the extra H+ it took on in the tissues
H+ reacts with HCO3- to form CO2 which is breathed out

22

Describe the formation of carbamino compounds

Carbon dioxide binds directly to proteins
Carbon dioxide binds directly to amine groups on globin of Hb
More carbamino compounds formed at the tissues because partial pressure of carbon dioxide higher

23

Name the 3 forms in which carbon dioxide is transported

Dissolved carbon dioxide (10%)
As hydrogen carbonate (60%)
As carbamino compounds (30%)

24

What is the concentration of carbon dioxide in the venous blood?

23 mmol/L

25

What is the partial pressure range for CO2 in the blood?

4.2 - 6.0 kPa

26

What is the partial pressure range for oxygen in the blood?

9.8 - 14.2 kPa

27

What is the reference range for concentration of HCO3- in the blood?

21-29 mmol/L

28

Why can the partial pressure of oxygen drop considerably before saturation is markedly affected?

Plateau at the top of the oxygen-Hb saturation curve
(Cooperative binding of Hb)

29

How long does the compensation of acidosis or alkalosis take in the kidneys?

Correction to the needed level of HCO3- takes 2-3 days

30

How is metabolic acidosis compensated by changing ventilation?

Increased ventilation
Decreases partial pressure of carbon dioxide
Increases the pH