diffusion/ventilation DSA

Question 1

what is FRC

Answer 1

functional residual capacity

volume of gas in the lung after normal expiration

Question 2

what is residual volume

Answer 2

air remaining in the lungs after maximal expiration

Question 3

what is inspiratory reserve volume

Answer 3

volume of air that can be inhaled after a normal respiration

Question 4

what is inspiratory capacity

Answer 4

maximal volume of air that can be inhaled from FRC

Question 5

what is expiratory reserve volume

Answer 5

volume that can be exhaled after a normal respiration

Question 6

what is vital capacity

Answer 6

maximal volume that can be expired after maximal inspiration (so includes a forceful expiration)

Question 7

what is tidal volume

Answer 7

amount of air entering the lungs during normal breathing

Question 8

what does helium dilution method measure?

Answer 8

FRC

b/c helium is basically insoluble in blood

Question 9

what does Body Plethysmography measure?

Answer 9

FRC

Question 10

what is perfusion limitation of gas diffusion?

Answer 10

amount of gas transported is limited by blood flow (partial pressure gradient is not maintained)

Question 11

what is diffusion limitation of gas diffusion?

Answer 11

amount of gas that is transported depends on the diffusion process (diffusion will continue as long as the partial pressure gradient is maintained)

Question 12

what are 4 pathological conditions that alter diffusing capacity

Answer 12

• Diffuse interstitial pulmonary fibrosis
– Thickening of the interstitium, alveolar wall and destruction of capillaries

• Chronic obstructive pulmonary disease
– Loss of lung elastic tissue and pulmonary capillaries (decreases surface area and total Hb content)

• Loss of functional lung tissue
– Decreases surface area and Hb content

• Anemia
– Fall in Hb content