pulmonary blood flow, gas exchange and transport Flashcards Preview

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Flashcards in pulmonary blood flow, gas exchange and transport Deck (12):
1

bronchial circulation

nutritive
supplied via bronchial arteries arising from systemic circulation
supplies oxygenated blood to airway smooth muscle, nerves and lung tissue

2

pulmonary circulation

gas exchange
L and R pulmonary arteries originating for right ventricle - carries entire cardiac output form RV
supplies capillary network surrounding alveoli - returns oxygenated blood to left atrium via pulmonary vein
high flow , low pressure system

3

rate of gas diffusion across membranes is...

down gradient form high to low
directly proportional to partial pressure gradient
directly proportional to gas solubility
directly proportional to availability of SA
inversely proportional to thickness of membrane - fastest over short distances

4

ventilation

air getting to alveoli L/min

5

perfusion

local blood flow L/min

6

distribution of blood flow in lungs

influenced by hydrostatic pressure and alveolar pressure
proportional to vascular resistance - declines with height across lung
at base blood flow is high - arterial pressure exceeds alveolar - vascular resistance is therefore low
at apex blood flow is low - arterial pressure is less than alveolar pressure - compresses arterioles - vascular resistance is increased

7

define shunt

dilution of oxygenated blood from better ventilated areas ( poor ventilation at some alveoli cause deoxygenated blood to pass into oxygenated blood )

8

autoregulation - when ventilation

if ventilation decreases in alveoli, Pco2 increases and Po2 decreases, blood flowing past theses alveoli do not get oxygenated
decreased tissue Po2 constricts the arterioles , diverting blood to better ventilated alveoli , increased Pco2 also causes mild broncho-dilation - to try increase ventilation
CONSTRICTION IN REPSONSE TO HYPOXIA IS SPECIFIC TO PULMONARY VESSELS - systemic vessels dilate

9

autoregulation - when ventilation > flow

alveolar dead space
increase in alveolar Po2 - pulmonary vasodilation ( more perfusion)
decrease in Pco2 - bronchial constriction ( reduced ventilation)
tries to bring perfusion:ventilation back to 1

10

alveolar dead space

alveoli that are ventilated but not perfused

11

anatomical dead space

air in conducting zones of airways that aren't available for gas exchange

12

physiological dead space

alveolar DS + anatomical DS