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S2 MAP II > Gas Exchange and Gas Transport > Flashcards

Gas Exchange and Gas Transport Flashcards

1
Q

what is emphysema

-leading cause

A

form of COPD
deterioration of the alveoli - less surface area
smoking is leading cause

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2
Q

diffusion

-what is it

A

process of randomly moving molecules making their way back and forth across the respiratory membrane

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3
Q

diffusion requires…

A

motion

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4
Q

total pressure at sea level

-composition

A 
760 mmHg
nitrogen: 78.62%
oxygen: 20.84%
CO2: 0.04%
water: 0.50%
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5
Q

nitrogen partial pressure

A

600 mmHg

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6
Q

oxygen partial pressure

A

160 mmHg

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7
Q

partial pressure of a gas in fluid is determined by

A

concentration

solubility coefficient of the gas

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8
Q

partial pressure in fluid

-equation

A

concentration of dissolved gas / solubility coefficient

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9
Q

solubility coefficient of O2 and CO2

A

O2
-0.024
CO2
-0.57

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10
Q

net rate of diffusion determined by…

A 
pressure difference
solubility of the gas in the fluid
cross-sectional area of the fluid
distance gas must diffuse
molecular weight of the gas
temperature of the fluid
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11
Q

diffusion is proportional to…

A 
(delta P x A x S) / (d x sqrt MW)
P: pressure
A: cross sectional area
S: solubility
d: diffusion distance
MW: molecular weight
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12
Q

diffusion coefficient of

  • oxygen
  • CO2
  • CO
  • nitrogen
  • helium
A 
oxygen
-1
CO2
-20.3
CO
-0.81
nitrogen
-0.53
helium
-0.95
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13
Q

respiratory gases

  • very soluble in…
  • -implication
A

very soluble in lipids

-diffusion across membranes occurs relatively easily

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14
Q

limiting factor in rate of diffusion of gas through tissue

A

water

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15
Q

purpose of concentration of O2, CO2, H2O, and N2 in making up pressure in body

A 
O2
-constantly being absorbed from alveoli
CO2
-constantly diffusion from blood into alveoli
H2O
-air is humidified in respiratory tract (water vaporizes)
-PH2O at body temperature = 47 mmHg
N2
-makes up balance to total 760 mmHg
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16
Q

change in N2 partial pressure in

  • atmospheric air
  • humidified air
  • alveolar air
  • expired air
A

highest in atmospheric air (597)

decreases in other 3 (similar values; 563.4 - 569)

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17
Q

change in O2 partial pressure in

  • atmospheric air
  • humidified air
  • alveolar air
  • expired air
A

highest in atmospheric air (159)
decreases to lowest in alveolar air (104)
slightly higher in expired air (120)

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18
Q

change in CO2 partial pressure in

  • atmospheric air
  • humidified air
  • alveolar air
  • expired air
A

0.3 in atmospheric and humidified air
40 in alveolar air
27 in expired air

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19
Q

change in H2O partial pressure in

  • atmospheric air
  • humidified air
  • alveolar air
  • expired air
A

3.7 in atmospheric air

47 in humidified, alveolar, and expired air

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20
Q

alveolar air replacement

A

get partial replacement of alveolar air with each breath
new air into alveoli with each breath - 350 ml (same amount of old air expired)
therefore, 1/7 alveolar air replaced by new air each breath

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21
Q

alveolar oxygen concentration

  • controlled by
  • PO2 in alveoli cannot exceed _____ at sea level
  • -why?
A

controlled by
-rate of absorption by pulmonary capillaries (amount leaving the alveoli)
-rate of oxygen entry into alveoli via ventilation (amount entering the alveoli
PO2 in alveoli cannot exceed 149 mmHg
-pressures of the other gases limits it

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22
Q

respiratory membrane

-rapid diffusion of gases aided by what properties of the tissues?

A

large surface area of respiratory membrane with small amount of blood spread throughout
small diameter of pulmonary capillaries

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23
Q

diffusion of gases through respiratory membrane

  • similar to
  • affected by…
A 
similar to diffusion fo gases through water
affected by
-thickness of membrane
-surface area of respiratory membrane
-diffusion coefficient
-pressure difference across the membrane
24
Q

respiratory membrane’s diffusion capacity

-what is it?

A

volume of a gas that will diffuse through the membrane each minute for a partial pressure difference of 1 mmHg

25
Q

normal Va/Q (ventilation perfusion ratio)

-what is it?

26
Q

what 2 Va/Q values would result in no gas exchange occurring?

A

zero (no ventilation)

infinity (no perfusion)

27
Q

what 2 factors determine the PO2 and PCO2 in the alveoli

A

ventilation rate

solubility

28
Q

what is the partial pressure at the arterial end for

  • O2
  • CO2
A

O2
-40 mmHg
CO2
-45 mmHg

29
Q

at rest, where does pulmonary diffusion occur?

A

in the first 1/3 of the capillary length

30
Q

bronchial arteries

-function

A

supply deep tissues of lungs and do not come into contact with lung air - returned via pulmonary veins

31
Q

PO2 in

  • interstitial fluid surrounding tissue cells
  • tissue cells
A

interstitial fluid
-40 mmHg
tissue
-5-40 mmHg

32
Q

tissue cells require _____ to fully support chemical processes

33
Q

transport of CO2 from tissues

  • CO produced when…
  • rate of CO2 diffusion compared to O2
A

CO2 produced in cell when O2 used; cellular CO2 pressure rises
pattern of diffusion and transport from tissue cell to alveoli follow same reasoning as O2 in opposite direction
CO2 diffuses much more rapidly than O2 (higher solubility)
-less pressure difference needed to to cause CO2 diffusion than O2 diffusion

34
Q

intracellular and interstitial PCO2

A

intracellular
-46 mmHg
interstitial
-45 mmHg

35
Q

affect of blood flow and metabolism on PCO2

A

decrease in blood flow at tissue interstitial fluid increases PCO2 in the fluid
increase in blood flow at tissue interstitial fluid decreases PCO2 in fluid
increase in metabolism increases interstitial fluid PCO2 at all blood flow levels

36
Q

hemoglobin

  • transports _____ % of O2 from lungs to tissues
  • -_____ carries the rest
A

97%

rest carried in H2O of plasma and RBCs

37
Q

oxygen-hemoglobin dissociation curve

  • illustrates…
  • PO2 has direct effect on _____
  • percent saturation of Hgb demonstrated by…
A

illustrates % of hemoglobin saturated by oxygen at any given point along transport route
PO2 has direct effect on O2 binding capacity
percent saturation of Hgb demonstrated by oxy-hemoglobin curve

38
Q

oxygen saturation of hemoglobin

  • PO2 when leaving lungs
  • -hemoglobin saturation at this point
  • PO2 at end of tissues
  • -hemoglobin saturation at this point
A 
PO2 lungs
-95 mmHg
-Hgb = 97%
PO2 end of tissues
-40 mmHg
-Hgb saturation = 75%
39
Q

15 grams of Hgb can carry _____ O2 in 100 mg blood (assuming 100% saturation)

40
Q

at rest, how much O2 is left at the tissues per 100 ml blood?

41
Q

oxygen release from hemoglobin under strenuous exercise conditions

A

increased O2 use with exercise
interstitial fluid PO2 can drop from 40 mmHg to 15 mmHg
result: 4.4 ml O2 left in 100 ml blood - net delivery of 15 mL to the tissues
combine with increased CO by 6-7x normal, can get 20-fold increase of O2 delivery to tissues

42
Q

factors that shift the curve to the right

A

increase in blood acidity (lower pH)
increase CO2
increased blood temperature
increased 2,3-biphosphoglycerate (BPG)

43
Q

factors that shift the curve to the left

44
Q

increase in H+ and CO2…

A

increase in H+ and CO2 shifts curve to right which enhances

  • release of O2 from Hgb in tissues
  • oxygenation of blood in lungs
45
Q

Bohr effect

  • what is it?
  • purpose
A

weakening of hemoglobin-oxygen bond

O2 unloaded where it is most needed

46
Q

curve shifts right during exercise due to…

A

increased CO2 produced
increased H+ in muscle capillary blood
increased temperature of blood

47
Q

normally, PO2 of _____ is sufficient for cellular reactions

48
Q

_____ is the limiting factor for reactions in the cellq

49
Q

carbon monoxide poisoning

A

CO combines with Hgb in same location at O2
PCO of 0.4 mmHg allows CO to compete with O2 in combining with Hgb; allows 1/2 of Hgb to bind with CO
PCO of 0.6 mmHg can be lethal
hyperbaric chamber can displace CO with O2 on Hgb

50
Q

under normal conditions, how much CO2 is transported per 100 mL blood from the tissues to the lungs

51
Q

how can CO2 be transported from the tissues to the lungs

A

CO2 in plasma (7%)
combines with H2o to form carbonic acid in the RBC
carbonic acid dissociated into H+ and HCO3-
-H+ combines with Hgb - “buffered”
-HCO3 diffuses out of RBC into plasma (70% of CO2 transport), Cl- diffuses into RBC
CO2-Hgb

52
Q

carbon dioxide dissociation curve

A

normal [CO2] in blood (i.e. volumes percent) is 50 volumes percent (50 mL CO2 per 100 mL blood)
4 mL exchanged during normal blood transport
dissociation curve - normal range of blood PCO2 is 45 mmHg in tissues and 40 mmHg in arterial blood

53
Q

effect of CO2 picked up in the tissues capillaries on pH

A

can decrease pH from 7.41 to 7.37

54
Q

respiratory quotient

  • what is it
  • equation
  • differs depending on…
  • approximates…..
  • precise determination of energy expenditure requires…
A

ratio of metabolic gas exchange
RQ = CO2 produced / O2 consumed
differs depending on type of substrate metabolized (carb, fat, protein)
approximates the nutrient mixture catabolized for energy during rest and exercise
precise determination of energy expenditure requires measuring both respiratory quotient and O2 consumption

55
Q

RER

  • compares…
  • R changes boased on…
A 
compares the CO2 output to O2 intake
R changes based on fuels for body metabolism
-carbs: R = 1
-fat: R = 0.7
-mix carb, fats, proteins: R = 0.85

S2 MAP II (17 decks)

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