ventilation and compliance

Question 1

what is anatomical dead space?

Answer 1

vol of gas occupied by conducting airways that is NOT available for gas exchange (150mL)

Question 2

what is tidal volume (TV)?

Answer 2

Vol breathed in and out at each breath (500mL)

Question 3

what is expiratory reserve volume (ERV)?

Answer 3

Max vol of air which can be expired from lungs at end of norm expiration (1100mL)

Question 4

what is inspiratory reserve volume (IRV)?

Answer 4

Max vol of air which can be inhaled into lungs at the end of normal inspiration (3000mL)

Question 5

what is residual volume (RV)?

Answer 5

The vol of gas in lungs at the end of maximal expiration (1200mL)

Question 6

what is vital capacity?

Answer 6

Tidal vol + IRV + ERV (4600mL)

Question 7

what is total lung capacity?

Answer 7

Vital capacity + RV (5800mL)

Question 8

what is inspiratory capacity?

Answer 8

TV + IRV (3500mL)

Question 9

what is functional capacity?

Answer 9

ERV + RV (2300mL)

Question 10

Describe the difference between pulmonary and alveolar ventilation:

Answer 10

Pulmonary ventilation is the total air movement in and out of the lungs

Alveolar ventilation is the fresh air getting to alveoli and therefore available for gas exchange

Question 11

what are the normal values for alveolar and arterial gas partial pressures:

Answer 11

Arterial gas:
PaCO2 = 35-45mmHg
PaO2 = 80-100mmHg

Alveolar gas:
PaO2 =
PaCO2 =

Question 12

what is surfactant produced by?

Answer 12

type 2 alveolar cell production starts at 25 weeks and is complete by 36 weeks.

It is stimulated by thyroid hormones and cortisol

Question 13

what is surfactant stimulated by?

Answer 13

It is stimulated by thyroid hormones and cortisol

Question 14

what is the role of surfactant?

Answer 14

decreases surface tension therefore lowering the risk of alveoli collapsing

it also decreases the lungs’ tendency to recoil and make breathing easier

Question 15

when does surfactant tension occur?

Answer 15

where there is an air-water interface, and refers to the attraction between water molecules.

Question 16

why is surfactant also effective in small alveoli?

Answer 16

as the surfactant molecules come closer together therefore increasing the concentration

Question 17

explain what the law of Laplace is:

Answer 17

The law of LaPlace states that pressure is higher in smaller alveoli (P=2T/r)

Where T is surface tension, r is radius and P is pressure

Question 18

what is compliance?

Answer 18

the change in volume relative to the change in pressure.

It is affected by disease w(emphysema etc.) and is also affected by age.

Compliance represents the stretchability of lungs

High compliance = large inc in lung volume for a small decrease in ip pressure

Low compliance = small inc in lung volume for a large decrease in ip pressure

Question 19

what is the difference between obstructive and restrictive lung disease?

give example

Answer 19

Obstructive = obstruction of airflow, especially on expiration

Restrictive= restriction of lung expansion

Obstructive; Asthma, COPD, emphysema, Chronic Bronchitis

Restrictive; CF, Infant Resp Distress, Oedema, Pneumothorax