PSL301: Respiratory 3 Flashcards Preview

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Flashcards in PSL301: Respiratory 3 Deck (44):
1

Dalton's law of partial pressures tells us that total atmospheric pressure =

the sum of all partial pressures + water
PB = PO2 + PCO2 + PN2 + PH2O
pB - pH2O = pO2 + PCO2 + PN2

2

formula: partial pressure

fractional concentration * total pressure

3

Normal value for PB

760 mmHg

4

Normally, O2 makes up __% of air

21

5

Normally, CO2 makes up __% of air

0.04

6

Difference between fractional concentration and concentration

Fractional: gas in gas
Concentration: gas in liquid

7

Why is water included in the calculation of PB?

Air is humidified in the airway

8

what is the normal pH2O?

47 mmHg

9

How much O2 and CO2 is in the alveoli? (aka how much is available for exchange?)

100 mmHg O2
40 mmHg CO2

Not all the O2 breathed in will be available for exchange

10

What determines how much gas dissolves into solution?

1. Partial pressure of the gas
2. Solubility of the gas
3. Temperature of the solution

11

What happens when gasses are at equilibrium?

the partial pressure will be the same in air and solution

12

LOWER/HIGHER partial pressure of a gas = increased solubility in water

Higher

13

What is more soluble, O2 or CO2?

CO2

14

Fick's Law of Diffusion

Gas transfer = constant * pp gradient * area / wall thickness

Constant includes solubility of that particular gas

15

Fick's Law of Diffusion tells us

amount of gas transfered

16

List the conditions that affect gas exchange

1. Emphysema
2. Fibrotic lung disease
3. Pulmonary edema
4. Asthma

17

How does emphysema affect gas exchange?

- alveoli destroyed
- less SA for gas exchange

Low/normal pO2 in lungs
Low pO2 in capillaries

18

How does Fibrotic lung disease affect gas exchange?

- thickened alveolar walls slow gas exchange
- loss of lung compliance may decrease ventilation

Low/normal pO2 in lungs
Low pO2 in capillaries

19

How does pulmonary edema affect gas exchange?

- more fluid in interstitial space, so distance travelled by O2 is longer

Normal pO2 in lungs
Low pO2 in capillaries

20

How does Asthma affect gas exchange?

- ventilation decreased

Low pO2 in lungs
Low pO2 in capillaries

21

How much O2 and CO2 are there left after passing the tissues?

pO2 = 40
pCO2 = 46

22

How is O transported in the blood?

>98% bound to Hb
<2% dissolved in plasma

23

At lungs, __% of Hb is saturated with O

98

24

At tissues, __% of Hb is saturated with O

75

25

How much O2 is released at the tissues?

25%

26

What happens to the Hb saturation curve as pH goes down?

right shift

27

As temperature goes down, what happens to the Hb saturation curve?

left shift

28

What factors affect affinity of Hb for O2?

1. pH
2. temp
3. pCO2

29

At higher pCO2, what happens to the Hb dissociation curve?

right shift

30

What is the effect of CO2 on Hb dissociation called?

Bohr effect

31

2 types of hemoglobin made during development

1. fetal hemoglobin
2. maternal hemoglobin

32

The Hb dissociation curve of fetal hemoglobin looks like...

left shift

33

When is fetal hemoglobin produced?

During development inside mom; stopped as soon as baby is born

34

Why is fetal hemoglobin different from maternal?

Higher affinity for O2 means that it can steal the O2 from mom at the placenta

35

Effect of 2,3 DPG on Hb dissociation

right shift

36

How is CO2 transported in the blood?

7% dissolved in plasma
23% bound to Hb = carbaminohemoglobin
70% in plasma as bicarb

37

Which enzyme catalyzes CO2 conversion to bicarb?

Carbonic anhydrase (CA)
CO2 + H20 H2CO3 H + HCO3-

38

Where is CO2 converted into bicarb?

erythorcytes

39

What buffers the H+ ions in RBC made during bicarb formation?

Hb

40

What happens when bicarb leaves the cell?

Chloride shift: Cl- enters in exchange

41

What is bicarb formation like at the tissues

CO2 enters the RBC and is converted to bicarb. The bicarb is released into plasma in exchange for Cl-

42

What is bicarb formation like at the lungs?

Bicarb enters the cell in exchange for Cl-. H+ is released from Hb to react with bicarb, forming CO2. CO2 is released by expiration.

43

What is the Haldane effect?

At any given pCO2, blood carries less CO2 at higher pO2

44

What is 1 application of the Haldane effect?

High pO2 at lungs means Hb blood will release CO2 to be exhaled.