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Resp > 02a: Ventilation and Diffusion > Flashcards

02a: Ventilation and Diffusion Flashcards

1
Q

Diffusion becomes the dominant mechanism of gas transport (before/beyond) which point in respiratory tree?

A

Beyond terminal bronchioles

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2
Q

Bulk flow: gas movement results from differences in (X). How does this differ from diffusion?

A

X = total pressure (i.e. total pressure gradient)

Diffusion: certain gas moves down its own partial pressure gradient

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3
Q

Linear velocity of flow is (high/low) in upper airways and (increases/decreases) as it approaches alveolar ducts due to increase in (X).

A

High;
decreases;
X = cross-sectional area (by nearly 5,000 fold)

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4
Q

T/F: Bulk flow essentially ceases in respiratory zone.

A

False - volume change seen in alveoli

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5
Q

Deposition of particulates in alveoli occurs as result of (X). How does the body take care of this?

A

X = low gas velocity

Macrophages remove the particulates

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6
Q

T/F: Diffusion in any lung is not rate-limiting.

A

False - in normal lung, but diffusion may be limited in diseased lung (emphysema)

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7
Q

List the 6 layers that gas must diffuse through in alveoli.

A
  1. Surfactant
  2. Alveolar epithelium
  3. Interstitium
  4. Pulmonary cap endothelium
  5. Plasma
  6. RBC membrane
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8
Q

In lung fibrosis, (diffusion/ventilation) is impaired because there’s a buildup of (X) in (Y) layer.

A

Diffusion;
X = collagen
Y = interstitial

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9
Q

Distance from surface of alveolus to capillary is about (X).

A

X = 0.05 mm

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10
Q

Comparing O2 and CO2 diffusion: if area, thickness, and partial pressure gradients are equal, which factors determine diffusion?

A
  1. Diffusion constant (dependent on MW)

2. Solubility

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11
Q

(CO2/O2) is (X) times more soluble in water than (CO2/O2).

A

CO2;
X = 24;
O2

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12
Q

PvCO2 and PvO2 values in pulmonary artery (venous blood).

A

PvCO2: 46 Torr
PvO2: 40 Torr

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13
Q

PaCO2 and PaO2 values in pulmonary vein (arterial blood).

A

PaCO2: 40 Torr
PaO2: 100 Torr

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14
Q

T/F: Arterial gas pressures of CO2 and O2 are equal to those in the lung.

A

True

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15
Q

Pressure gradient in lung for O2 and CO2.

A

O2: 60 Torr
CO2: 6 Torr

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16
Q

T/F: Due to 10x higher pressure gradient in lung, O2 diffuses about 2x faster than CO2.

A

False - CO2 diffuses 2x faster due to greater solubility

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17
Q

Gas exchange that is perfusion-limited is dependent on (X). This is the case of (normal/diseased) lung.

A

X = blood flow (i.e. increased blood flow, increased gas transport);

Normal

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18
Q

Gas exchange that is diffusion-limited is dependent on (X). This is the case of (normal/diseased) lung.

A

X = diffusion..

Diseased

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19
Q

T/F: PO2 in blood depends on concentration of gas in solution and bound to Hb.

A

False - partial pressure only depends on concentration of gas in solution

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20
Q

At low concentration of inhaled CO, capillary PCO is about (X) Torr. Why? Is CO diffusion or perfusion limited?

A

X = 0;
Diffusion limited; binds Hb at very high affinitiy, so diffuses along capillary without equilibrating (negligible amount of CO in solution)

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21
Q

Since He (does/doesn’t) diffuse into blood from alveolar gas, it’s used along with CO to indicate (X).

A

Doesn’t;

How much original gas mixture was diluted within alveoli

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22
Q

T/F: In diseased lung, non-uniformity can prevent diffusion problem from being detected.

A

True

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23
Q

Diseased lung: pulmonary edema may be not be detected (aka no change in total lung diffusing capacity). Expliain.

A

Recruitment of capillaries in other, healthy parts of lung; blood flow bypasses alveoli that may be filled with fluid, so these non-aerated regions won’t contribute to diffusing capacity measurement

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24
Q

Diffusion capacity of lung changes by changing (X) via which mechanisms?

A

X = Perfusion;

Recruitment and distension

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25
Q

There’s an initial (rise/fall) in alveolar O2 and (rise/fall) in alveolar CO2 during inspiration. What accounts for this?

A

Fall; rise

Mixing of alveolar gas with gas from dead space

26
Q

Alveolar PO2 reaches peak rise in (inspiration/expiration) and begin subsequent drop in (inspiration/expiration). This allows comparison of which rates?

A

Inspiration; inspiration (just before expiration)

Rate of O2 delivery in inspired gas is slower than rate of removal of O2 from alveoli

27
Q

Alveolar PCO2 reaches peak drop in (inspiration/expiration) and begin subsequent rise in (inspiration/expiration). This allows comparison of which rates?

A

Inspiration; inspiration (just before expiration)

Rate of CO2 to inspired gas is slower than rate of removal of CO2 from alveoli

28
Q

In steady state respiration, neither (X) nor (Y) of CO2 and O2 change appreciably over time.

A 
X = flow of gas
Y = mean alveolar partial pressures
29
Q

Fraction of CO2 in alveolar gas is directly proportional to (X) and inversely proportional to (Y).

A 
X = amount CO2 produced each minute (at BTPS)
Y = minute alveolar ventilation
30
Q

The alveolar gas equation allows simple calculation of pressure of (X) at a given (Y).

A 
X = alveolar CO2
Y = CO2 production
31
Q

RER or RQ is defined as (X) and usually equal to which value(s)?

A

X = (amount CO2 added into alveoli)/(amount O2 removed from alveoli)

Less than 1 (about 0.8)

32
Q

Under which condition would RER equal 1?

A

Pure carbohydrate being metabolized

33
Q

CO2 stores are (lesser/equal/greater) than/to O2 stores in body. This means alveolar PCO2 take(s) (longer/equal/shorter) time than PO2 to equilibrate.

A

Greater;

longer

34
Q

T/F: Oxygen is poorly soluble in plasma.

A

True

35
Q

T/F: RBCs are nearly all Hb by volume.

A

True

36
Q

RBCs occupy (X)% of blood volume.

A

X = 40-50

37
Q

T/F: Myoglobin has heme prosthetic group and binds O2 with higher affinity than Hb.

A

True

38
Q

T/F: Hb, but not myoglobin, binds oxygen reversibly.

A

False - both do

39
Q

Hb and Mgb: (X) is responsible for preventing irreversible (oxidation/reduction) of (ferrous/ferric) ion to (ferrous/ferric) ion.

A

X = distal histidine residue

Oxidation;
Ferrous; ferric

40
Q

Oxygen binding curve for myoglobin has (X) shape. Myoglobin is 50% saturated at (Y) P of O2.

A 
X = hyperbolic
X = 2 mmHg (2 Torr)
41
Q

How many O2 binding sites does myoglobin have?

A

One

42
Q

Carbaminohemoglobin has (X) bound. And carboxyhemoglobin has (Y) bound.

A 
X = CO2
Y = CO
43
Q

T, aka (X), conformation of Hb: O2 (is/isn’t) bound. And Hb has (low/high/equal) affinity for O2 compared to R conformation.

A

X = taut;
isn’t
Lower

44
Q

R, aka (X), conformation of Hb: O2 (is/isn’t) bound. And Hb has (low/high/equal) affinity for O2 compared to T conformation.

A

X = relaxed;
Is;
High

45
Q

(T/R) conformation of Hb results from rupture of some ionic/H bonds aka salt bridges.

A

R

46
Q

Describe the “lever” effect in Hb.

A

Binding of O2 causes small shift of Fe into plane of heme group, which then causes much larger shift (rotation) in surrounding structure

47
Q

Binding of first O2 molecule to Hb enhances binding of second by factor of (X). By the time 3 O2 molecules are bound, remaining binding site has (Y) times the affinity for O2.

A 
X = 3;
Y = 20
48
Q

When 50% of Hb oxygenated, most tetramers are bound to either (1/2/3/4) O2 or (1/2/3/4) O2 molecules.

A

0 (deoxygenated) or 4 (fully oxygenated)

49
Q

Highest point of Hb saturation is (X)% in lungs. And lowest is (Y)% in tissues. Thus, (Z)% of bound O2 will actually be released in tissues.

A 
X = 98
Y = 32
Z = 66
50
Q

2,3-DPG stabilizes (oxy/deoxy) form of Hb, thus shifting the O2 binding curve (right/left).

A

Deoxy;

Right

51
Q

2,3-DPG is highly (cationic/anionic). It binds (X) part of (oxy/deoxy) Hb.

A

Anionic;
X = central cavity;
Deoxy-Hb

52
Q

T/F: Oxygenation of Hb expels 2,3-DPG.

A

True

53
Q

Rapidly metabolizing tissue releases high concentrations of (X), which promotes stabilization of (T/R) Hb and (binding/releasing) of O2.

A

X = H and CO2
T;
Release

54
Q

T/F: Both Hb and myoglobin display Bohr effect by shifting curves to the right.

A

False - Mgb shows little Bohr effect

55
Q

List the two ways that CO2 release from tissues (increases/decreases) O2 affinity of Hb.

A

Decreases;

  1. CO2 becomes bicarbonate and protons release (equation shift)
  2. CO2 reacts with N-term of Hb to form carbamates
56
Q

Carbamate is formed when (X). This aids in transport of (Y) to (Z).

A 
X = CO2 binds N-term of Hb
Y = CO2
Z = lungs
57
Q

Carbamate formation stabilizes (oxy/deoxy)-Hb state because of the (positive/negative) charged group that stabilizes (X) formation.

A

Deoxy;
Negative;
X = salt bridge

58
Q

The Haldane effect describes which phenomenon?

A

Deoxygenation of blood increases its ability to carry CO2

59
Q

(X) is the principal Hb in adults. It has how many beta and alpha and gamma chains?

A

X = Hb alpha

2 beta and 2 alpha

60
Q

(X) is the principal Hb in fetuses. It has how many beta and alpha and gamma chains?

A

X = Hb gamma

2 alpha and 2 gamma

61
Q

(Fetal/maternal) RBC/Hb has higher O2 affinity. This is because (X) instead of (Y) residue causes:

A

Fetal;
X = serine
Y = histidine

Lowers fetal Hb affinity for DPG

62
Q

The major site of resistance to airflow within the respiratory system is located in the:

A

Medium bronchioles

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