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314 Exam 3 Gas Exchange and Transport > Gas Exchange and Transport > Flashcards

Gas Exchange and Transport Flashcards

1
Q

Atmospheric air

A

a gaseous mixture of approximately 78% nitrogen, 21% oxygen, 0.04% carbon dioxide, and minute amounts of other gases.

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2
Q

partial pressure of oxygen in atmospheric air

A

(pO2)

approximately 160 mmHg

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3
Q

partial pressure of carbon dioxide

A

(pCO2)

approximately 0.3 mmHg

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4
Q

When air and water meet at the respiratory membrane

A

each gas diffuses along its concentration gradient until its partial pressure in air equals its partial pressure in water

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5
Q

pO2

A

relatively higher in alveolar air, blood “loads” oxygen in the lungs

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6
Q

pCO2

A

relatively higher in alveolar blood, it “unloads” carbon dioxide in lungs

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7
Q

pO2 in alveolar air versus pO2 in the blood

A

pO2 in alveolar air is approximately 104 mmHg, while pO2 in the blood entering the capillaries is approximately 40 mmHg

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8
Q

oxygen in alveolar gas exchange

A

will diffuse along a pressure gradient out of the alveoli and into the blood

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9
Q

pCO2 in the blood versus in alveolar air

A

pCO2 in the blood entering the capillaries is approximately 46 mmHg while pCO2 in alveolar air is approximately 40 mmHg

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10
Q

The rate of alveolar gas exchange at high altitudes

A

the pO2 is low; pressure gradient is smaller and less oxygen diffuses into blood

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11
Q

The rate of alveolar gas exchange under hyperbaric conditions

A

pO2 is very high; pressure gradient is great, more oxygen diffuses into blood

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12
Q

Solubility of the gases in respiratory fluids

A
  • Oxygen is only 5% soluble in blood plasma
  • nitrogen is only 2.5% soluble in blood plasma
  • carbon dioxide is the most soluble of the gases in blood plasma
    it quickly diffuses even though it has smallest pressure gradient
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13
Q

Respiratory membrane

A

relatively thin so gases diffuse across it without difficulty

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14
Q

Surface area of the respiratory membrane

A

large enough to facilitate gas exchange

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15
Q

oxygen carried in the blood plasma

A

oxygen does not dissolve easily, so only 1.5% is carried in the blood plasma

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16
Q

formation of oxyhemoglobin (HbO2)

A

oxygen diffuses into the blood and quickly moves into erythrocytes where it combines with the heme portion of hemoglobin to form oxyhemoglobin

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17
Q

amount of oxygen carried as oxyhemoglobin

A

98.5%

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18
Q

oxyhemoglobin dissociation curve

A

the extent to which oxygen binds reversibly with hemoglobin depends on pO2 according to the oxyhemoglobin dissociation curve

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19
Q

oxyhemoglobin dissociation curve- at low pO2

A

(in tissue capillaries)- hemoglobin is only partially saturated

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20
Q

oxyhemoglobin dissociation curve- at high pO2

A

(in pulmonary capillaries) - hemoglobin becomes fully saturated

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21
Q

pCO2 in tissue cells

A

is approximately 45 mmHg, while pCO2 in tissue capillaries is about 40 mmHg

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22
Q

carbon dioxide diffusion

A

CO2 will diffuse along its pressure gradient out of the cells through interstitial space, into tissue capillaries where much of it will enter erythrocytes

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23
Q

carbonic anhydrase (CAH)

A

catalyzes reaction between carbon dioxide and water to form carbonic acid which dissociates into bicarbonate and hydrogen ions

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24
Q

Chloride shift

A

most bicarbonate ions are pumped out of erythrocytes and replaced with chloride ions duirng chloride shift, which maintains balance of anions

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25
Q

hyrdogen ions combine with

A

hemoglobin to prevent a change in blood pH

26
Q

pO2 in tissue capillaries versus tissue cells

A

pO2 in tissue capillaries is about 95 mmHg, while pO2 in tissue cells is about 40 mmHg

27
Q

oxygen diffusion

A

O2 will diffuse along its pressure gradient out of the blood through interstitial fluid into cells

28
Q

how does pO2 in the tissues affect the rate at which oxygen is unloaded from oxyhemoglobin

A

low pO2 in the tissues promotes elease of oxygen from oxyhemoglobin

29
Q

how does temperature affect the rate at which oxygen is unloaded from oxyhemoglobin

A

an increase in temperature causes more oxygen to be released from oxyhemoglobin

30
Q

how does pH affect the rate at which oxygen is unloaded from oxyhemoglobin

A

a drop in pH causes more oxygen to be released from oxyhemoglobin (Bohr effect)

31
Q

What affect do hydrogen ions have when they bind to hemoglobin

A

when hydrogen ions bind to hemoglobin- the 3-dimensional structure is altered and it reduces its oxygen- carrying capacity

32
Q

BPG

A

a metabolic byproduct produced when erythrocytes break down glucose by glycolysis and its presence promotes oxygen unloading

33
Q

Carbon monoxide

A

a colorless, odorless gas produced by incomplete combustion

34
Q

carbon monoxide binding to hemoglobin versus oxygen binding to hemoglobin

A

carbon monoxide binds to hemoglobin 200 times more tightly than oxygen binds to hemoglobin, which drastically reduces oxygen-carrying capacity of hemoglobin

35
Q

How much of the carbon dioxide generated is trasnported as dissolved gas in blood plasma

A

5%

36
Q

The carbon dioxide transported as dissolved gas in blood plasma accounts for how much of carbon disoxide exchange between the blood and the alveolar capillaries

A

7%

37
Q

How much of the carbon dioxide generated is trasnported as carbaminohemoglobin

A

5%

38
Q

carbaminohemoglobin

A

when carbon dioxide binds to amino groups on the polypeptide chains of hemoglobin

39
Q

The carbon dioxide transported as carbaminohemoglobin accounts for how much of carbon disoxide exchange between the blood and the alveolar capillaries

A

23%

40
Q

a low pO2

A

results in less saturated Hemoglobin

41
Q

How much of the carbon dioxide generated is trasnported as bicarbonate ions in blood plasma

A

90%

42
Q

The carbon dioxide transported as bicarbonate ions in blood plasma accounts for how much of carbon disoxide exchange between the blood and the alveolar capillaries

A

70%

43
Q

bicarbonate ions combine with hydrogen ions to do what

A

reform carbonic acid; carbonic anhydrase enzyme breaks it down into carbon dioxide and water

44
Q

reverse chloride shift

A

chloride ions are removed from erythrocytes

45
Q

where does carbon dioxide diffuse in order to be exhaled

A

out of the blood into alveoli

46
Q

blood gives up dissolved carbon dioxide gas and carbon dioxide from carbaminohemoglobin _____ _____ than it gives up CO2 from bicarbonate ions

A

more easily

47
Q

an increase of pCO2 has what affect on oxyhemoglobin

A

causes oxyhemoglobin to release its oxygen and transport more carbon dioxide

48
Q

Chemoreceptors

A

in the medulla oblongata, carotid arteries, and aorta are senstive to changes in hydrogen ions, carbon dioxide, and oxygen in the blood

49
Q

control of breathing during rest

A

aimed primarily at regulating the concentration of hydrogen ions in the brain

50
Q

drowning victims

A

have water in their lungs because H+ builds up as result of insufficient ventilation (involuntary inspiration)

51
Q

Normal blood pH

A

between 7.35 and 7.45

52
Q

respiratory acidosis

A

when blood pH falls below 7.35 because of problems with pulmonary ventilation

53
Q

respiratory alkalosis

A

when blood pH rises above 7.45 because of problems with pulmonary ventilation

54
Q

common cause of respiratory acidosis

A

a slight increase in pCO2

55
Q

when pCO2 rises above 43 mmHg

A

hypercapnia occurs and causes acidosis

56
Q

what do chemoreceptors signal when acidosis occurs and why

A

inspiratory area to increase rate and depth of breathing

57
Q

hyperventilation

A

allows the body to exhlae carbon dioxide faster than it forms; will shift carbonic acid reaction to left and get rid of hydrogen ions to bring pH up to “normal”

58
Q

common cause of respiratory alkalosis

A

a slight decrease in pCO2

59
Q

when pCO2 falls below 37 mmHg

A

hypocapnia occurs and causes alkalosis

60
Q

what do chemoreceptors signal when alkalosis occurs

A

they do not signal inspiratory area- so rate and depth of brathing remain slow and shallow

61
Q

hypoventilation

A

allows body to accumulate carbon dioxide faster than it can be exhaled; will shift carbonic acid reaction to right and produce more hydorgen ions to bring pH down to “normal”

62
Q

oxygen concentration and the impact on respiration

A

oxygen concentration usually has little impact on respiration because hemoglobin is usually highly saturated
- only if arterial pO2 falls dramatically will ventilation be affected.

314 Exam 3 Gas Exchange and Transport (1 decks)

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