Lung Volumes

Question 1

What determines lung volumes?

Answer 1

• Size
   Age
   Gender
   Anatomical build

Question 2

Why have asthma patients an increased Residual Volume?

Answer 2

Early airway closure in Asthma

• Increased small airway resistance>
• Increased loss of pressure in small airways>
• Early small airway closure, decreased FVC and increased RV

Question 3

Why have emphysema patients an increased Residual Volume?

Answer 3

Early airway closure in Emphysema
- Loss of lung tissue >
Decreased lung recoil >
Increased intrapleural pressure > Early small airway closure, decreased FVC and increased RV

Question 4

What increases first during exercise, tidal volume or respiratory rate?

Answer 4

The tidal volume. Any increase in the tidal volume will increase the alveolar ventilation by the same amount. Any increase in respiratory rate will increase alveolar ventilation by a smaller amount due to the anatomical dead space, more effort is spent to shift air in and out of the anatomical dead space without taking part in gas exchange.

Question 5

alveolar ventilation

Answer 5

= (tidal volume - dead-space volume) x respiratory rate

Question 6

pulmonary ventilation (ml/min)

Answer 6

= tidal volume (ml/breath) x respiratory rate (breath/min)

Question 7

physiological dead space

Answer 7

V/Q > 1
v = ventilation (airflow)
q = perfusion (blood flow)

Question 8

area where perfusion is greater than ventilation

1

Answer 8

decrese O2 in area > increase contraction of local pulmonary-arteriolar smooth muscle > constriction of local blood vessles > increase vascular resistance > decrease blood flow

Question 9

area where perfusion is greater than ventilation

2

Answer 9

increase co2 > relaxation of local airway smooth muscle > dilation of local airwya s> decrease airway resistance > increase airflow

Question 10

area where ventilation is greater than perfusion

1

Answer 10

increase O2 in area >relaxation of local pulmonary-arteriolar smooth muscle > dilation of local blood vessles > decrease vascular resistance > increase blood flow

Question 11

area where ventilation is greater than perfusion

2

Answer 11

decrease co2 > contraction of local airway smooth muscle > constriction of local airways> increase airway resistance > decrease airflow

Question 12

physiological shunt

Answer 12

V/Q < 1