Physiology: ventilation perfusion & alveolar dead space

Question 1

what is meant by ventilation(V)

Answer 1

the rate at which gas is passing through the lungs

Question 2

what is meant by perfusion(Q)

Answer 2

the rate at which blood is passing through the lungs

Question 3

describe what is meant by the V/Q ratio

Answer 3

the ratio between ventilation and perfusion changes from top to bottom of the lungs, and can in pathology

Question 4

what is alveolar dead space

Answer 4

ventilated alveoli that are not adequately perfused with blood are considered alveolar dead space
(very small + of little importance normally)

Question 5

what is the physiological dead space

Answer 5

alveolar dead space + anatomical dead space

Question 6

what can happen to alveolar dead space in disease

Answer 6

can increase significantly

Question 7

what causes an increase in alveolar O2 conc.

Answer 7

increased ventilation

Question 8

what causes the accumulation CO2 in alveoli

Answer 8

increased perfusion

Question 9

what does increased ventilation lead to

Answer 9

pulmonary vasodilation which increases blood flow to match larger airflow

Question 10

what does increased perfusion lead to

Answer 10

decreases airway resistance leading to increased airflow

Question 11

in an area where perfusion(rate blood flow) is greater than ventilation(rate airflow) what will happen to CO2, O2, airflow, blood vessels, blood flow and airways

Answer 11

CO2 increases in area
O2 decreases
airflow increases
local airways dilate
blood flow decreases
local blood vessels vasoconstrict

Question 12

in an area where ventilation is greater than perfusion what will happen to CO2, O2, airflow, blood vessels, blood flow and airways

Answer 12

CO2 decreases in area
O2 increases
airflow decreases
local airways constrict
blood flow increases
local blood vessels vasodilate