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Physiology Part 2 > Lec39 System in Special CIrcumstance > Flashcards

Lec39 System in Special CIrcumstance Flashcards

1
Q

What does exercise do to oxygen consumption?

A

increases oxygen consumption

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2
Q

What is fick’s principle?

A

Qt = V.O2 / (CaO2 - Cvo2)

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3
Q

What is equation for V.O2 [rearrangement of fick’s principle]?

A 
V.O2 = Qt ( CaO2 - CvO2)
V.O2 = ox consumption
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4
Q

What three things can you do to increase VO2 [ox consumption]?

A
  • increase cardiac output [Qt]
  • increase CaO2
  • decrease CvO2
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5
Q

What is equation for oxygen content [CaO2]?

A

CaO2 = 1.34 Hb SaO2 + 0.003 PaO2

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6
Q

What two things could you do to increase oxygen content [CaO2]?

A
  • increase hemoglobin [long term change]
  • increase arterial oxygen content

means increasing saturation [but already close to 100%]

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7
Q

What is equation for minute ventilation [Ve]?

A

Ve = Vt * frequency

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8
Q

What is resting Ve?

A

6 L / min

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9
Q

What 2 things could you do to raise Ve [minute ventilation]? Are these rapid or long term changes?

A
  • raise Vt to VC [vital capacity] = can get 8x increase
  • raise frequency
    both rapid changes that occur in exercise
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10
Q

What happens in exercise?

A
  • raise CO
  • raise Vt to vital capacity [VC]
  • raise frequency of breaths
  • improve V/Q maching –> lungs become more ideal
    increased muscle oxygen extraction
  • same or slight increase PaO2
  • increased ox saturation
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11
Q

What happens to V/Q matching in exercise?

A

improves –> lungs become more ideal

  • increase CO so get more Q
  • get more /bigger breaths in so increase V
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12
Q

What happens to PaO2 in exercise?

A

goes up a bit if anything

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13
Q

What happens to oxygen saturation with exercise?

A

increases if anything

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14
Q

Why do you get increased CO2 in exercise?

A

you start having anaerobic metabolism and producing lactate and get decreased pH. You get rid of lactate by turning it into CO2

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15
Q

What happens to blood supply to muscles in exercise? how much of CO goes to muscle at rest vs max exercise

A
  • during exercise, blood shunted away from other organs

- at rest muscles get 20% of CO, at max exercise get 80%

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16
Q

What are 3 mech by which muscle get more blood supply in exercise

A
  • increased CO
  • increase in vascular resistance to skin, viscera, other inactive tissues
  • decease in vascular resistance to working muscles
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17
Q

How do PaO2/PaCO2/pH change in exercise?

A
  • same or slightly higher PaO2
  • same PaCO2
  • low pH from lactate production
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18
Q

What is the anaerobic threshold?

A

threshold at which run out of ox at tissue level and start making lactate. function of how good your heart is at pushing blood around not how good your lungs are
- on ox uptake vs ventilation graph its the point at which the slope stops being linear because you have such extra CO2 from lactate that you need to breath harder to get rid of it

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19
Q

If you breath 100% O2 how does ox uptake vs ventilation graph change?

A
  • becomes totally linear because you have more O2 coming in so you don’t have the lactate build up
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20
Q

What is equation for CO? How can you increase it?

A 
Qt [CO] = SV * Hr
decrease parasympathetic flow to SA
increase sympathetic to SA
increase circulating catecholamines
increase SV via increased venous return or increased contractility
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21
Q

What is limiting factor for max exercise in normal man?

A

ccardiac output

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22
Q

What happens to O2 consumption in exercise?

A

increases

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23
Q

What happens to CO2 production in exercise?

A

increases

24
Q

What happens to ventilation rate in exercise?

A

increases

25
Q

What happens to arterial PO2 and PCO2 in exercise?

A

no change [maybe very small increase PO2]

26
Q

What happens to arterial pH in exercise?

A
  • no change in moderate exercise

- decrease in strenuous exercise

27
Q

What happens to venous PCO2 in exercise?

A

increaes

28
Q

What happens to pulmonary blood flow and CO in exercise?

A

increases

29
Q

What happens to V/Q ratio in exercise?

A

more evenly distributed throughout lung

30
Q

What happens to physiologic dead space in exercise?

A

decreases

31
Q

What happens to O2-hemoglobin dissociation curve in exercise?

A

shifts to right –> decreased affinity

32
Q

What happens to P50 in exercise?

A

increases

33
Q

What happens to ventilation rate in high altitude? what is driving force for it?

A
  • hyperventilation

- driven by hypercapnia [high CO2] primarily rather than hypoxia

34
Q

What is use of carbonic anhydrase inhibitors in high altitude?

A

carbonic anhydrase inhibitors cause metabolic acidosis to increase ventilatory drive

35
Q

What does hyperventilation do to CO2, pH, ventilatory drive?

A
  • hyperventilation lowers CO2

- produces respiratory alkalosis so at first decreases ventilatory drive

36
Q

What are 2 ways of adapting to high altitude?

A
  • polycythemia: increase Hb

- increased 2,3 DPG

37
Q

What is polycythemia? possible negative effect?

A

increases Hb

possible negative effect: can increase blood viscosity

38
Q

What is effect of 2,3 DPG?

A
  • shifts oxyhemoglobin dissociation curve to right
  • decreased affinity O2
  • increased unloading ox at tissue level but lose some loading at lung
39
Q

What are two potential problems of adapting to altitude?

A
  • hypoxic pulmonary vasoconstriction

- CNS complaints

40
Q

What is effect of hypoxic pulmonary vasoconstriction?

A
  • get high altitude pulmonary edema

- long term can get right ventricular overload –> right ventricle hypertrophy

41
Q

What CNS complaints occur in high altitude?

A

headache, nausea, fatigue, insomnia

42
Q

What is reason that climbing everst without oxygen you get higher PaO2 that you would think?

A

air is very dry

43
Q

What happens to alveolar PO2 in high altitude? why?

A

decrease – due to decreased barometric pressure

44
Q

What happens to arterial PO2 in high altitude? why?

A

decrease – due to hypoxemia

45
Q

What happens to ventilation rate in high altitude? why?

A

increase – hyperventilation due to hypoxemia

46
Q

What happens to arterial pH in high altitude? why?

A

increase – respiratory alkalosis due to hyperventilation

47
Q

What happens to Hg conc in high altitude?

A

increase due to increased RBC conc over time in high altitude

48
Q

What happens to 2,3 DPG conc in high altitude?

A

increase over time

49
Q

What happens to O2-hemoglobin dissociation curve in high altitude? P50? affinity?

A

shifts to right, increased P50, decreased affinity

50
Q

What happens to pulmonary vascular resistance in high altitude? why?

A

increase due to hypoxic vasoconstriction

51
Q

What happens to pulmonary arterial pressure in high altitude? why?

A

increase secondary to increased pulmonary resistance

52
Q

by how many atm/torr does pressure increase for every 33 ft depth saltwater?

A

1 atm or 760 torr for every 33 ft

53
Q

In diving do you have increased or decreased pressure?

A

increased pressure

54
Q

What causes decompression sickness?

A
  • huge increased N pressure at deept depth
  • N diffuses into tissues
  • on rapid ascent, can come out of solution and cause bubbles in circulation
55
Q

What 2 possible problems in diving?

A
  • nitrogen narcosis

- decompression sickness

56
Q

How much ox in nitrox? what is it good for?

A
  • nitrox has higher oxygen and less nitrogen

- usually 32% oxygen

57
Q

At what PiO2 can you get acute CNS toxicity?

A

1000 torr

Physiology Part 2 (19 decks)

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