4-Pulmonary Circulation Ventilation/Perfusion

Question 1

bronchial circulation

Answer 1

only 1-2% of CO directed this pathway
-delivers oxy blood from L heart to bronchi/bronchioles/nerves/lymph/visceral pleura
-empties into bronchial and pulmonary veins

mild reduction of PaO2

Question 2

pulmonary pressure maintained by

Answer 2

large # of pulmonary capillaries maintain low pressure and resistance

highly compliant vascular bed lower vascular tone

Question 3

how resistance stays low

Answer 3

-recruitment of capillaries when inc CO
-distention inc when inc CO

dec risk of pulmonary edema

Question 4

respiratory cycle on pulmonary resistance

Answer 4

inhale = compress pulmonary caps so inc pulmonary vascular resistance
exhale reverse

Question 5

dec alveolar PO2 =

Answer 5

dec pulmonary cap blood flow, blood redistributed to better aerated alveoli

Question 6

hypoxic pulmonary vasoconstriction

Answer 6

unique to lungs
-vessels around alveolus constrict
-triggered by airway obstruction, ventilation fail, lung damage, high altitude, COPD

if persistent the contribute to pulmonary arterial hypertension

Question 7

gravity zones on perfusion

Answer 7

zone 1 = ventilated but not perfused, arterial P < alveolar pressure, top of lung
zone 2 = flow dep on gradient b/t arterial and alveolar
zone 3 = arterial > venous > alveolar, base of lung, best perfused

Question 8

v/q ratio is highest

Answer 8

in apex
lowest in base

Question 9

blood gases at apex

Answer 9

high ventilation = higher PO2 and lower CO2
-closer to fresh air values

Question 10

blood gases at base

Answer 10

high perfusion = lower PO2 and higher CO2

closer to pulmonary arterial blood values

Question 11

v/q mismatch

Answer 11

lower than normal ventilation or blood flow
-perfusion without vent = shunt, v/q = 0
-ventilation without perfusion = clot, dead space, v/q = infinite

v/q should normally be between 0.8-1.0 close match

Question 12

V/Q mismatch dead space symptoms/signs

Answer 12

pulmonary embolism from thrombi, hydrostatic pressure failure, emphysema

-severe rspir distress
-severe chest pain
-right ventricle failure
-hypoxemia
-hypotension

Question 13

extrapulmonary shunt

Answer 13

blood routed from right heart to left without aterialization in lungs
-septal defects

Question 14

intrapulmonary shunt

Answer 14

complete obstruction of area of airway like mucus plug or fluid

Question 15

factors that affect capillaries and fluid

Answer 15

-intravascular hydrostatic pressure (blood vol)
-intersitial hydrostatic pressure
-capillary osmotic prssure (plasma proteins, electrolytes)
-intersitial osmotic

Question 16

inc cap hydrostatic pressure

Answer 16

-left heart fail
-inc pulm venous pressure
-inc cap hydrostatic
=edema

Question 17

inc cap permeability

Answer 17

vascular injury = inc protein leakage = dec colloid osmotic pressure
edema

Question 18

dec intersitial hydrostatic pressure

Answer 18

loss of surfactant = inc surface tension = dec interstitial P = edema

Question 19

dec colloid oncotic pressure

Answer 19

starvation = loss plasma proteins / dec colloid P
edema

Question 20

implication of edema

Answer 20

1. inhibit gas exchange
2. restrict small airwys and dec lung compliance