Test 3: Wk 11: 9 High Altitude, Exercise, and Deep Sea Adaptations - Puri Flashcards
Owles Point represents
ventilation increase above the predicted by an extrapolation of the linear part of the ventilation/ oxygen consumption relationship
Anaerobic Threshold
point where alveolar ventilation increase is disproportionate to O2 consumption
any increase in O2 consumption beyond owles point leads to
greater increase in alveolar ventilation that what is required
disproportionate — occurs after the anaerobic threshold
hyperventialtion
PaCO2 =
PaCO2 = VCO2 / VA
before anaerobic threshold is reached, VA increases proportional to
VCO2
at normal work loads PaCO2, PaO2 and pH are — than anaerobic threshold
less than
Exercise Hyperpnea
not hyperventilation, metabolic rate has increased and so has ventilation
— most likely drives surplus alveolar ventilation during exercise
lactic acid
lactate — and blood pH — once anaerobic threshold is met
incerase; decrease
metabolic acidosis stimulates
peripheral chemoreceptors to increase ventilation
inspiration increase disproportionately greater than
CO2 production
PaCO2 — and PaO2 — at high workloads due to alveolar ventilation
decreases; increases
Anaerobic threshold
point where alveolar ventilation increase is disproportionate to O2 consumption
any increase in O2 consumption beyond Owles point leads to
greater increase in alveolar ventilation that what is required
Surplus alveolar ventilation is most likely driven by
lactic acid
PaCO2 =
PaCO2 = VCO2 / VA
before Anaerobic threshold is reached
VA increases proportional to VCO2
at normal workloads PaCO2, PaPO2, and pH are — than anaerobic threshold
less than
Exercise Hyperpnea
not hyperventilation
metabolic rate has increased and so has ventilation
lactate — and blood pH — once anaerobic threshold is met
metabolic acidosis stimulates
metabolic acidosis stimulates
peripheral chemoreceptors to increase ventilation
ventilation increases disproportionately greater than
CO2 production
PaCO2 — and PaO2 — at high workloads due to alveolar ventilation
decreases; increases
— will not be effected until ventilation changes
PaCO2
Impaired mental function from hypoxia is due to
direct effect of hypoxia on brain tissue and from cerebral vasoconstriction from hypocapnia
cerebral vasoconstriction is causes by
hypocapnia
Acute exposure altitude sickness 5km sx
amnesia, dizziness, breathless at rest, insomnia, anorexia
Acute exposure altitude sickness 10km sx
loss of consciousness
Acute exposure altitude sickness ~20km sx
body fluids boil
why does hyperventilation occur during acclimation to high altitude
increased sensitivity of peripheral chemoreceptors
PAO2 =
PAO2 = PIO2 - PACO2
PIO2 at high altitudes
decreases
Hypercapnia
higher than normal PaCO@ >45
Hypocapnia
lower than normal PaCO2 <40
Hypocapnia can result only from an alveolar ventilation that is
excessive in relation
to carbon dioxide production
— is a common cause of hypocapnia
Hypoxemia
Hypoxemia occurs in
congenital heart disease
with right- to-left shunting, residence at high altitude, Po2 below about 60mmHg.
Hypocapnia secondary to hypoxaemia opposes the
ventilatory response to the
hypoxemia.
Metabolic acidosis produces a compensatory
hyperventilation
Neurological disorders may result in — and —
hyperventilation and hypocapnia
Hypercapnia is most commonly caused by
ventilatory failure due to acute or chronic conditions
ARDS is an example of
acute ventilatory failure
COPD is an example of
chronic ventilatory failure
every 10m of seawater is — atm
1 additional atm
10m below surface of sea atm =
2 atm
N2 is highly lipid soluble and
high N2 interferes with
ion channels and slows ion conductance
Mild nitrogen narcosis resembles
alcohol
intoxication
“Martini’s law”
each 15 m of depth has the effects of drinking an additional martini.
Solution to nitrogen necrosis in scuba diving
replace nitrogen with helium in the SCUBA tanks. Helium is more inert than
nitrogen and has less side effects.
Mild oxygen toxicity
disorientation and headaches
Severe oxygen toxicity
damage to the airways, pulmonary edema, coma, and death.
solution to oxygen toxicity in scuba diving
scuba tank mixture is typically 98% helium and inly 2% oxygen. This is enough
to achieve PaO2 similar to sea levels due to high barometric pressures
Decompression sickness (DCS or bends) is caused by
local bubble formation,
either in tissues or in venous blood
DCS Bubbles in veins cause
obstruction, leading to capillary leaks
Mild or type I DCS
mild pains (“niggles”), pruritus, a skin rash, and deep throbbing pain (bends),
Serious or type II DCS
CNS, lungs, and circulatory system.
CNS disorder in dysbarism
most commonly involving the spinal cord—reflects bubble formation in the myelin sheath of axons, which compromises nerve conduction
dizziness—the staggers—to paralysis.
Pulmonary symptoms in dysbarism
the chokes—
result from bubbles that originate in the systemic veins and travel as gas emboli to
lodge in the pulmonary circulation, and include burning pain on inspiration
circulatory system dysbarism
bubbles not only can
obstruct blood flow but also can trigger the coagulation cascade, leading to the
release of vasoactive substance
Arterial gas embolization (AGE) is caused by
bubbles that enter the systemic arterial blood via either tears in the alveoli or right-to-left shunts and then become wedged in the brain or other organs.
Best treatment of dysbarism is
recompression
