Respiratory adaptions DSA

Question 1

what will the RQ be in a diabetic/hypoglycemic patient?

Answer 1

0.7- relying solely on FFA

Question 2

what is the normal RQ?

Answer 2

0.8

Question 3

what is the RQ of a patient on IV glucose solution?

Answer 3

1.0

Question 4

what happens when the V/Q ratio decreases?

Answer 4

perfusion (adding CO2 to alveoli and removing O2) is happening quicker than ventilation

this decrease in O2 in the alveoli leads to an decrease in arterial O2 (PaO2) along with an increase in arterial CO2

ventilation is not keep up with metabolic needs

Question 5

what happens when there is an increase in V/Q?

Answer 5

increase in ventilation and a decrease in perfusion

increase in PAO2 and therefore an increase in PaO2

decrease in PACO2 and PaCO2

ventilation is in excess of metabolic needs

Question 6

what is V/Q in pulmonary embolism and what are the effects?

Answer 6

V/Q becomes very low or essentially 0

the blood will be very oxygenated, however very little of it and leads to low blood volume

wasted energy by giving blood to this dead alveolar space

** I think it starts out high V/Q and then compensatiion happens (discussed in other lecture) leads to low V/Q

Question 7

what is V/Q in choking or an allergic reaction and what effects does it have?

Answer 7

V/Q is low or close to zero

blood coming to lungs but cant get oxygenated so it looks like venous blood

wasted energy getting blood to the non funcitoning lungs–> physiological shunt (anatomic is when blood physically cannot get to lungs)

Question 8

what is V/Q in COPD or emphysema?

Answer 8

some areas of body get hight V/Q and others low

some alveoli are large and arent near blood vessels (less O2 leaving blood) but some alveoli are getting too much blood, along with the destruction of capillaries (less CO2 being put into lungs)

V/Q mismatches contribute to hpoxia and hypercapnia

Question 9

what is respiratory quotient?

Answer 9

relationship between O2 and CO2 in tissues where this exchange occurs

RQ= V_dotCO2/ V_dotCO2

**V_dot= volume per unit time

Question 10

How is alveolar PO2 calculated and each of the equations individual components?

Answer 10

PAO2= inspired oxygen- oxygen consumed

** difference between amount of O2 in alveoli and amount of O2 consumed by tissues

inspired oxygen= difference between atmospheric pressure (780 mm Hg) and water vapor added by airways before reaching alveoli (about 47 mm Hg) multiplied by percent oxygen in atmosphere (21%)

oxygen consumed= measured by amount of CO2 produced (40 mm Hg) and RQ –> PaCO2/RQ

should be a little under 100 mm Hg

Question 11

how does body compensate in low V/Q?

Answer 11

hypoxic conditions–> vasocontricts (decrease blood flow/perfusion to hypoxic regions)

Question 12

how does body compensate in high V/Q?

Answer 12

bronchocontstricts to decrease ventilation in areas of alveolar dead space (not receiving blood)

Question 13

what is hyppoxic hypoxia?

Answer 13

PaO2 is low because of low PAO2 or blood cant form an equilibrium with air because of a diffusion impairment (emphysema or fibrosis or low environment oxygen)

Question 14

what is anemic hypoxia? what causes it?

Answer 14

lungs work fine but the blood loses O2 carrying capacity

can be caused by anemia or carbon monoxide poisoning which leads to build up of CO2 that has much higher affinity for Hb

Question 15

what is circulatory hypoxia? what causes it?

Answer 15

lungs and blood capacity are just fine but the heart is unable to deliver blood to tissues

could be due to clot or sickle cell anemia

Question 16

what is histotoxic hypoxia? what can cause it?

Answer 16

lungs, blood capacity, and heart working just fine. there is oxygen there but the tissues are unable to use it becuase of poison

cyanide can cause this

Question 17

what is direct stimulus to increase firing rate of central chemoreceptors?

what happens when they are stimulated?

Answer 17

H+ ions in CSF

carbonic anhydrase produces both HCO3 and H+ ions which then the choroid will separate (HCO3 goes to CSF to reset pH and H+ go to blood to be excreted—> raises the pH of CSF)

once pH has been adjusted, firing rate returns to normal levels

Question 18

in the early stages of COPD, when PaO2 and PaCO2 are low, will ventilation increase or decrease?

will his H+ concentration be lower or higher?

Answer 18

increase to keep oxygen levels up

lower (less CO2 means less H+)–> will increase pH

Question 19

when ventilation increases, futhering the decrease in PaCO2 (resulting in hypocapnia), how do the chemoreceptors reset to bring PaCO2 back up? why do they need to do this?

Answer 19

make CSF more acidic (to get back to normal value) due to the choriod plexus putting more H+ ions into blood (or less HCO3)

works thru carbonic anhydrase

CO2 and O2 are low which has counter effects… need to increase O2 levels overrides that of CO2

Question 20

how do the central chemoreceptors compensate in chronic hypercapnia?

Answer 20

choroid plexus adds more bicarbonate to CSF (while H+ ions excreted from kidney)

Question 21

what are the 3 steps that are in response to acute hypoxia (min-hrs) (n regards to both COPD and increase in altitude?

Answer 21

1. increase in ventilation due to increase of peripheral chemoreceptors firing (they detect low PaO2)
2. PaO2 increases and PaCO2 decreases
3. decrease PaCO2 decreases firing of central chemoreceptors

Question 22

what are the three events that take place in acclimization (chronic hypoxia/hypocapnia)?

Answer 22

**due to the immediate effects of hypoxia, ventilation has been increased which has in turn decreased PaCO2

1. choroid plexus will reset CSF to produce more H+ ions and less HCO3, which will in turn allow the body to continue increasing ventilation
2. kidney releases more erthyropoientin–>stimulates bone marrow to produce more RBC’s–> increases hematocrit–> increases O2 carrying capacity in blood
3. cells increase their number of mitochondria which allows for more anaerobic glycolysis

Question 23

how does cerebral vasculature respond to altitude sickness?

Answer 23

dilate the vessels with local factors—> increase perfusion therefore increases filtration—> produces cerebral edema (especially if autoregulation/downstream vasocontriciton not working)

Question 24

how are the lungs impacted by altitude sickness?

Answer 24

increased pulmonary vascular permeability—> pulmonary edema

also pulmonary hypertension due to local hypoxic vasoconstriction which causes more work for right ventricle

Question 25

fact to know on barometric pressure

Answer 25

for every 10 m you go below water surface, pressure increases by 1 atm

Question 26

how do you calculate total barometric pressure?

Answer 26

pressure due to water + pressure due to air

ex: (40 m * (1 atm /10 m)) + 1 atm

= 5 atm

Question 27

what is the effect oxygen can have in hyperbaric conditions?

Answer 27

formation of superoxide anion (O2-) and hydrogen peroxide (H2O2) which are toxic to cells

** 100% oxygen supp at 4 atm will cause serious effects in half the population

Question 28

what effect does nitrogen have in hyperbaric pressure?

Answer 28

as pressure increases, amount of nitrogen dissolving into plasma increases

can cause nitrogen narcosis- N2 harms the CNS which makes the person act drunk

as we ascend, the extra n2 that was dissolved into the plasma, must leave the body and will become a gas to be breathed out of the lungs.. if ascent is too quick, N2 becomes gas in blood and causes the bends or decompression sickness

Question 29

how does an air embolism form?

Answer 29

when a diver rapidly ascends with a closed glottis, the expanding air in the body cannot exit the lungs and are pushed into the blood instead—> this can rupture the pulmonary veins and put the air into the blood

Question 30

how do you calculate A-a pressure gradient?

Answer 30

PAO2- PaO2

*PaO2 should normally be given

Question 31

what are peripheral chemoreceptors stimulated by?

Answer 31

hypoxia, hypercapnia, and (somewhat) pH