DSA: Respiratory Adaption in Health & Disease

Question 1

How do you calculate P_AO₂

and what is normal

Answer 1

99.7 mmHg

Question 2

what is the alveolar-arterial O2 gradient

& what is normal

Answer 2

< 12 mmHg

(8 + 20% age)

Question 3

what is ventilation-perfusion ratio

Answer 3

ratio of air to alveoli & amount of blood sent to lungs

normal = 0.8

Question 4

what are normal P_A & P_a values

Answer 4

Question 5

what decreases V/Q

what happens to the partial P of O2 & CO2

Answer 5

1. decreased V - not bringing enough O2 for metabolic needs & not blowing off enough CO2 (decreased ventilation- hypoventilation)
2. increase Q - more blood cells coming to remove O2 & deliver more CO2 than exhale (increase blood flow)

P_A/aO₂- decrease & P_A/aCO₂ ​- increase

Question 6

what increases V/Q

what happens to the partial P of O2 & CO2

Answer 6

1. increased ventilation (hyperventilation) - ventilation in excess of metabolic need met by perfusion –> blow off CO2 and increase O2

PA/aO₂- increase & PA/aCO₂ - decrease

Question 7

what happens to V/Q when you stand up

Answer 7

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

Question 8

what happens to V/Q if perfusion is 0

-when does this happen

Answer 8

pul embolism

V/Q increases to infinity

Question 9

when does V/Q decrease to 0

Answer 9

stop ventilation to part of lung

Question 10

what is hypoxic vasoconstriction

Answer 10

low V/Q

-redirect blood coming to area w/ low ventilation –> decrease perfusion of hypoxic region

Question 11

what is bronchoconstriction

Answer 11

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

Question 12

what is anoxia

Answer 12

deoxy blood delivered to tissures

Question 13

what is hypoxemia

Answer 13

deoxy blood

Question 14

what is hypoxic hypoxia

Answer 14

P_aO₂ decrease b/c -

P_AO₂ decrease or blood unable to equilibrate w/ alveolar air

Question 15

what is anemic hypoxia

Answer 15

O2 carrying capacity decreased

anemia=CO is binding Hb & sickle cell anemia

Question 16

what is circulatory hypoxia

Answer 16

tissue to recieving sufficient O2 b/c heart cant pump blood to tissues

(sickle cell anemia)

Question 17

what is histotoxic hypoxia

Answer 17

cells are poisoned - tissues cant use O2

-cyanide poisoning

Question 18

what do central chemoreceptors do

Answer 18

detect P_aCO₂ by measuring [H+} of CSF

Question 19

what happens to ventilation in early lung disease

Answer 19

decrease SA (emphysema) –> increase ventilation

Question 20

what happens w/ hypocapnia

Answer 20

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

Question 21

how are central chemoreceptors reset

Answer 21

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

Question 22

what is the response to high altitude

Answer 22

immediate - hypoxia - peripheral chemoreceptor - increase ventilation –> increase P_aO₂

Increase alveolar ventilation –> increase P_aO₂ & decrease P_aCO₂ –> decrease in CO2 –> decrease central chemoreceptor firing –> decrease ventilation

Question 23

what are long term effects of high altitude

Answer 23

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

Question 24

what is altitude sickness

Answer 24

1. related to changes in cerbral circulation during hypoxia
   - vessels dilate –> increase perfusion & filtration –> mild edema
2. pul edema - rapid ascend/descent - increase pul vasculature permeability –> pul HTN bc hypoxic vasoconstriction