DSA: Respiratory Adaption in Health & Disease Flashcards
How do you calculate PAO2
and what is normal
99.7 mmHg
what is the alveolar-arterial O2 gradient
& what is normal
< 12 mmHg
(8 + 20% age)
what is ventilation-perfusion ratio
ratio of air to alveoli & amount of blood sent to lungs
normal = 0.8
what are normal PA & Pa values
what decreases V/Q
what happens to the partial P of O2 & CO2
- decreased V - not bringing enough O2 for metabolic needs & not blowing off enough CO2 (decreased ventilation- hypoventilation)
- increase Q - more blood cells coming to remove O2 & deliver more CO2 than exhale (increase blood flow)
PA/aO2- decrease & PA/aCO2 - increase
what increases V/Q
what happens to the partial P of O2 & CO2
- increased ventilation (hyperventilation) - ventilation in excess of metabolic need met by perfusion –> blow off CO2 and increase O2
PA/aO2- increase & PA/aCO2 - decrease
what happens to V/Q when you stand up
change blood flow to different parts - increase flow base of lung & decrease flow apex
- decrease V/Q at base
- increase V/Q at apex
- middle lung - normal
what happens to V/Q if perfusion is 0
-when does this happen
pul embolism
V/Q increases to infinity
when does V/Q decrease to 0
stop ventilation to part of lung
what is hypoxic vasoconstriction
low V/Q
-redirect blood coming to area w/ low ventilation –> decrease perfusion of hypoxic region
what is bronchoconstriction
high V/Q
-bronchi constrict slightly to increase resistance & decrease amount of ventilation to areas that are poorly perfused - limit amount of dead space & minimize wasted work
what is anoxia
deoxy blood delivered to tissures
what is hypoxemia
deoxy blood
what is hypoxic hypoxia
PaO2 decrease b/c -
PAO2 decrease or blood unable to equilibrate w/ alveolar air
what is anemic hypoxia
O2 carrying capacity decreased
anemia=CO is binding Hb & sickle cell anemia
what is circulatory hypoxia
tissue to recieving sufficient O2 b/c heart cant pump blood to tissues
(sickle cell anemia)
what is histotoxic hypoxia
cells are poisoned - tissues cant use O2
-cyanide poisoning
what do central chemoreceptors do
detect PaCO2 by measuring [H+} of CSF
what happens to ventilation in early lung disease
decrease SA (emphysema) –> increase ventilation
what happens w/ hypocapnia
low O2, low CO2
-low H+ –> decrease activation of chemoreceptors –> decrease activation of medullary resp centers
–> peripheral chemoreceptor respond to low O2 by sending excitation –> increase resp BUT central receptors respond to low COS –> decrease resp
how are central chemoreceptors reset
choroid plexus has carbonic anydrase in cell –> take metabolic CO2 –> H+ & HCO3-
if resp acidosis - add more HCO3- to CSF
if basic - add H+ to CSF
what is the response to high altitude
immediate - hypoxia - peripheral chemoreceptor - increase ventilation –> increase PaO2
Increase alveolar ventilation –> increase PaO2 & decrease PaCO2 –> decrease in CO2 –> decrease central chemoreceptor firing –> decrease ventilation
what are long term effects of high altitude
basic CSF –> choroid plexus add more H+ to CSF –> bring pH back to normal
hypoxia - increase release of erythropoietin from kidney –> stimulate RBC by bone marrow –> increase hematocrit –> increas Hb in blood –> increase O2 carrying capacity
cells of body have increase in number & size of mitochondria – increase anaerobic glycolysis
what is altitude sickness
- related to changes in cerbral circulation during hypoxia
- vessels dilate –> increase perfusion & filtration –> mild edema - pul edema - rapid ascend/descent - increase pul vasculature permeability –> pul HTN bc hypoxic vasoconstriction
