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PHYL 4504 > Respiratory System Under Stress > Flashcards

Respiratory System Under Stress Flashcards

1
Q

Barrometric pressure ____ with distance above earth’s surface

A

decreases

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2
Q

there is significant ___ associated with high altitude

A

hypoxia

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3
Q

what is the partial pressure of water vapour at body temperature?

A

47 mmHg

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4
Q

Who was the woman who worked with Henderson and Scneider on the mountains/tracks

A

Mabel Fitzgerald

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5
Q

What did Mabel Fitzgerald results show?

A

alveolar PO2 and PCO2 values

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6
Q

AT altidue, what happens to alveolar PCO2?

A

It falls, due to increased ventilaion, even in acclimatized people

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7
Q

breathing ____ causes most of the space in alveoli occupied by N2 to be filled with O2 - therefore has significant effects on arterial O2 saturation

A

pure O2

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8
Q

Acute effects of hypoxia in an unaclimatized person starts at

A

120000 ft

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9
Q

symptoms of acute hypoxia

A

drowsiness, lassitude, mental and muscle fatigue, headache, nausea, euphoria - higher = twitching and seizures, above 23000 death

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10
Q

what is the significant problem of acute hypoxia?

A

decreased metnal capacity - which decreases judgement, memory and performance of discrete motor movements

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11
Q

Where is the death zone?

A

26000ft - loss of physiological functioning or death due to wrong decisions made as a result of decreased mental capacity

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12
Q

Mountain sickness has 3 phases, what are they?

A

Acute cerebral edema, acute pulmonary edema, and chronic mountain sickness

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13
Q

Acute cerebral edema

A

result of local vasodilation of cerebral blood vessels due to hypoxia - increased blood flow to capilaries, increase pressure and causing fluid to leak into cerebral tissue - can cause severe disorientation

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14
Q

Acute pulmonary edema

A

cause unclear, genetic factors, severe hypoxia causes pulmonary arterioles to constric in a non uniform manner = more and more blood in pulmonary vasculature is pumped thorugh fewer and fewer unconstricted vessels - increase pressure in these parts of lungs, resulting in fluid leakage and local edema = pulmonary edema spreads with loss of funciton

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15
Q

Chronic mountain sickness

A

can develop in people remaining at high altitude

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16
Q

5 symptoms of chronic mountain sickness

A

red blood cell mass and hematrocrit increase and increase blood viscovity and decreases blood flow to tissues, pulmonary arterial pressure becomes more elevated as arterioles constrict this happens in the whole lung. right heart becomes enlarged and starts to fail, peripheral arterial pressure falls, congestive heart failure occurs = death is not moved to lower elevation

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17
Q

Acclimatization

A

adaptation to decreased PO2 and deleterious effects of hypoxia decrease - able to work harder without hypoxia or ascend further

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18
Q

What are the 5 main mechanisms of acclimatization

A

1 Hyperventilation
2 increase number red blood cells (polycythemia)
3 increased vascularity in peripheral tissues
4. increase efficiency of cells to use O2
5. increased diffusing capacity of the lungs

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19
Q

Hyperventilation

A

immediate exposure to low PO2 stimulates arterial chemoreceptors = increase ventilation rate - more expired CO2 and increase pH - inhibition of brain stem resp centers which opposes the effects of low PO2 to stimulate respiration cia peripheral chemoreceptors which is the opposite of what you want - this effect fades after a few days due to excretion of HCO3 and consequent decrease in CSF which decreases pH in fluids around chemosensitive neurons in resp center and increases resp stimulation

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20
Q

the sensitivty of the carotid bodies to hypoxia ____ during acclimatization

A

increases

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21
Q

people born at high altitude have a ____ ventilatory response to hypoxia

A

diminished

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22
Q

people born at sea level that move to altitude retain ____ for a long time

A

hypoxic response

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23
Q

Gradual decrease in HCO3 is brought about by what

A

compensation by the kidneys responding to resp alkylosis - reducing secretion of H+ and increase HCO3- excretion - this gradually reduces plasma and CSF HCO3 and pH towards normal

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24
Q

Polycythemia

A

increase in Hb concentration and O2 binding capacity

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25
Q

what is the result of polycythemia

A

although O2 saturation is reduced, levels of O2 in blood may be normal

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26
Q

When exposed to low O2 for several weeks, what rises?

A

hematocrit, Hb concentration, blood volume = increase in total body Hb of 50%

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27
Q

What is the stimulus for increased red blood cell production?

A

hypoxemia - triggers erythropoeitin production form kidneys which stimulates erythorcyte production in the bone marrow

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28
Q

What does polycytehmia also do that is not good

A

increases blood viscocity

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29
Q

Increased vascularity in peripheral tissues

A

cardiac output can increase after moving to high altitude - this decreases during acclimatization as blood hematocrit increases - result is total O2 transported remains constant - also increased growth of systemic circulatory capillaries in non resp tiissue - angiogenesis - occures especially in animals and people born at high altitudes

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30
Q

Use O2 more efficiently at the cellular level

A

hypoxia enduces HIFs hypoxia inducing factors - DNA binding transcirption factors that induce several genes that enhance O2 delivery to tissues and enhance energy metabolsim

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31
Q

what are some genes that increase O2 efficiency at cellular level

A

vascular endothelial GF, erythropoeitin gene, mitcochrondrial genes, glycolitic enzymes, increased NO availability

32
Q

Increase diffusing capacity

A

increases thee fold during exercise and at high altitude - increase pulmonary capillary blood volume which expands capilaries and increases SA abvailable for diffusion - also increased pulmonary arterial pressure which forces blood into more alveolar capilaries, especiall in upper parts ot the lung - improves VQ distribution

33
Q

Pulmonary vasoconsriction

A

in repsonse to alveolar hypoxia- incresing pulmonary arterial pressure and the work done by the right heart = hypertrophy of the right heart - uniform blood flow thought sometimes pulmonary edema

34
Q

Natural acclimitization of native high altitude dwellers

A

larger chest size, smaller body suze, higher ratio fo ventilatory capacity to body mass, larger hearts, increase CO, O2 Hb dissociation curve altered

35
Q

People born at altitude can achieve daily work output _____ to lowlanders at sea level and is not possible to achieve with acclimitization

A

almost equivalent

36
Q

What happens to alveolar PO2 at high altitude?

A

decreased (barrometric pressure)

37
Q

What happens to arterial PO2 at high altitude?

A

decreased (hypoxemia)

38
Q

What happens to ventilaiton rate at high altitude?

A

increased - hyperventilation due to hypozemia

39
Q

What happens to arterial pH at high altitude?

A

increased (resp alkalosis due to hyperventilation)

40
Q

What happens to Hb concentration at high altitude?

A

increased (increased red blood cell concentration)

41
Q

What happens to 2,3 DPG at high altitude?

A

increased

42
Q

What happens to O2 Hb dissociation curve at high altitude?

A

shifts to right, increase P50 - decreased affinity

43
Q

What happens to pulmonary vascular resistance at high altitude?

A

increased due to hypoxic vasoconstriction

44
Q

What happens to pulmonary arterial pressure at high altitude?

A

increased secondary to increased pulmonary resistance

45
Q

At the beginning of flight and end, what do we experience

A

linear acceleration and deceleration

46
Q

during turns, what force do we expeirence?

A

centrifugal acceleration

47
Q

Centrifugal acceleration is determien by

A

f = mvsquared /r

48
Q

as velocity increases, what happens to F

A

increases in proportion to v squared

49
Q

f is also proportional to what?

A

sharpness of the turn

50
Q

Acceleratory force is denoted by

A

G

51
Q

centrifugal acceleratory forces affect the circulatory system because____

A

blood can be translocated

52
Q

Effect of positive G force on blood

A

blood is centrfuges toward lower body, as pressure in lower body vessles increase, vessles dilate passively, resulting in major portion of blood in lower vessels and away from upper - heart cannot pump the amount of blood pooled in this wat, so less available to meet cardiac output demands

53
Q

what happens to systolic and diastolic pressure in upper body when a centrifugal force (+) is applied

A

both pressured fall for the first few seconds, then return to systolic of 55 and diastolic of 20 within 10-15 seconds

54
Q

what is the seocnd recovery in pressure caused by

A

activation of barroreceptor reflexes

55
Q

extremely high acceleratory forces cause

A

fracture vertebrae

56
Q

Negative G causes

A

transient hyperemia to head, psychotic disturbance due to brain edema, small vessels can rupture - not as bad as you think because CSF goes to head as well and acts as a buffer outside the brain - hyperemia in eyes can result in temporary blindness

57
Q

G forces in space travel impossible to withstand unless

A

semi reclining position

58
Q

weightlessness - people in orbit experience microgravity with what G force

A

near-zero

59
Q

what problems do microgravity cause?

A

motion sickness (unfamiliar pattern of motion signals in brain), trnaslocation of fluids in body, diminshed physical activity because muscles no longer act against gravity

60
Q

What happes to the V and P distribution in lungs

A

becomes more uniform - improvement in gas exchange

61
Q

What else happens during space travel in the body?

A

thoracic blood volume intitally increases, decalcification of bone and muscle atrophy, small reduction of red cell mass

62
Q

pressure ____ tremendously when people go beneath surface of sea

A

increase

63
Q

Boyle’s law means that as pressure increases, gas volume becomes ___

A

compressed

64
Q

increased pressure can cause

A

lung collapse

65
Q

At high pressures, N2 can cause

A

narcosis - comparable to being drunk

66
Q

Oxygen toxicity at high pressure - when PO2 in blood rises above 100 mmHg

A

amount of O2 dissolved in blood increases markedly

67
Q

Oxygen poisnoning 3 stages

A

Acute, ROS production, Chronic

68
Q

Acute O2 toxicity

A

brain seizures, nausea, muscle twitchiness, dizziness, visual distrubances, irritability, disorientation

69
Q

ROS production due to O2 toxicity

A

Hb O2 buffering system fails and Oxygen radicals attack proteins, lipids, and DNA - CNS particularly susceptible de to high lipid content = brain dysfunction

70
Q

Chronic O2 toxicity

A

lung congestion and edema, and cells lining airways and alveoli are damaged

71
Q

CO2 toxicity is not usually a problem but can occur with..

A

some types of rebreathing apparatuses

72
Q

Beyond 80mmHg PACO2, respiraotyr centres become ___ and breathing ____

A

depressed, start to fail

73
Q

CO2 toxicity causes

A

severe resp acidosis, varying degrees of lethargy, narcosis and anesthesia

74
Q

N2 and compression sickness

A

body water and fat eventually becomes saturated with N2, not metabolized so remains dissolved until process reversed - can result in decompression sickness if person returns to surface too quickly

75
Q

significant quantities of N2 can come out of solution and form bubbles which…

A

can block small blood vessels - can combine to cause large bloackages - tisseu ischemia

76
Q

What are symptoms of N2 compresison sickness

A

joint and muscle pain, CNS symptoms, dizziness and unconsciousness, massive micro bubbles plus pulmonary capillaries, leading to severe shortness of breath, pulmonary edema and death

PHYL 4504 (8 decks)

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