Exchange of air gases Flashcards

1
Q

What are the major gases?

A

Nitrogen, oxygen, carbon dioxide, water

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2
Q

Minor gases

A

argon, neon, helium, methane

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3
Q

Atmospheric pressure

A

sum of all gas contributions

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4
Q

Dalton’s Law

A

total pressure of a gas mixture is equal to the sum of the partial pressures of its individual gases

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5
Q

Alveolar air is altered by

A

contact with mucus membranes, water pressure incr
mixing with residual air leftover from previous respiratory cycle, carbon dioxide pressure incr, oxygen pressure decr
rapid exchange of O2 and CO2 with blood

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6
Q

For oxygen to reach the blood what must it do?

A

dissolve in the aqueous layer
cross the respiratory membrane

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7
Q

Alveolar gas exchange

A

transport of oxygen and carbon dioxide across the respiratory membrane

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8
Q

What dictates the direction of flow?

A

pressure gradient of each gas in the air and fluid

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9
Q

Does one gas influence diffusion of another in the alveolus?

A

no

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10
Q

How long does it take for alveolar gas exchange to reach equilibrium?

A

0.25 seconds

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11
Q

What factors affect the efficiency of alveolar gas exchange?

A

pressure gradient of gases
solubility of gases
thickness of respiratory membrane
area of respiratory membrane
ventilation-perfusion coupling

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12
Q

If ventilation is good and oxygen is present, what increases?

A

perfusion

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13
Q

Blood flow matches

A

airflow in the lungs

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14
Q

In systemic tissues if there is poor oxygen do you get vasodilation or vasoconstriction?

A

vasodilation

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15
Q

In lung tissues if there is poor oxygen, do you get vasodilation or vasoconstriction?

A

vasoconstriction

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16
Q

oxyhemoglobin

A

hemoglobin with one or more oxygen bound to it

17
Q

deoxyhemoglobin

A

hemoglobin without oxygen

18
Q

One hemoglobin molecule can carry how many oxygen molecules ?

A

four

19
Q

Each heme has how many iron atoms ?

A

1

20
Q

Cooperative binding

A

when one molecule of oxygen binds others hop on more easily

21
Q

Carbon monoxide binds 210x more tightly to hemoglobin than oxygen which could lead to ?

A

poisoning or suffocation

22
Q

How is carbon dioxide transported?

A

most is hydrated to form carbonic acid
binds to amino groups of plasma proteins and hemoglobin
could also be carried away in blood

23
Q

Haldane effect

A

binding of oxygen to hemoglobin promotes the release of carbon dioxide from hemoglobin

24
Q

Bohr effect

A

the affinity of hemoglobin for oxygen is proportional to pH

25
Q

In systemic gas exchange where does carbon dioxide go? What about oxygen?

A

carbon dioxide goes into the capillary blood
oxygen goes into the repairing tissue

26
Q

In alveolar gas exchange where does the carbon dioxide go? What about oxygen?

A

carbon dioxide goes into the alveolar air
oxygen goes into the capillary blood

27
Q

What is oxygen unloading influenced by ?

A

Low oxygen/ambient oxygen pressure
high temperature
high acidity
Bisphosphoglycerate

28
Q

Bisphosphoglycerate is influenced by which 5 stimuli?

A

thyroxine
testosterone
fever
growth hormone
adrenaline/epinephrine

29
Q

What is normal blood pH ?

A

7.35-7.45

30
Q

What is normal carbon dioxide pressure in the blood?

A

40 mmHg

31
Q

What is normal oxygen pressure in the blood?

A

95 mmHg

32
Q

What monitors the composition of blood and CSF?

A

central and peripheral chemoreceptors

33
Q

What is the most potent stimulus for breathing?

A

pH

34
Q

Acidosis

A

high CO2
blow off CO2 by increasing ventilation

35
Q

Alkalosis

A

Low CO2
retain CO2 by reducing ventilation

36
Q

Hyperventilation

A

response to acidosis
pushes reaction to the left: CO2 + H2O <- H2CO3 <- HCO3^- + H^+

37
Q

Hypoventilation

A

response to alkalosis
shifts reaction to the right which decreases pH

38
Q

How does carbon dioxide in the blood influence respiratory rate?

A

brain responds to increased CO2 at the start of exercising
CO2 can cross blood brain barrier to react with water in CSF to make hydrogen ions

39
Q

How does oxygen in the blood influence respiratory rate?

A

not as much effect on respiration as H ions or carbon dioxide
if hypoxemia can significantly stimulate ventilation