Physiology

Question 1

What are the forces keeping the alveoli open?

Answer 1

Transmural pressure gradient
Pulmonary surfactant
Alveolar interdependance

Question 2

What are the forces promoting alveolar collapse?

Answer 2

Elasticity of stretched pulmonary connective tissue

Alveolar surface tension

Question 3

At what point in pregnancy do babies produce their own surfactant?

Answer 3

Very late pregnancy

Question 4

What problem do premature babies often experience?

Answer 4

Respiratory distress syndrome as they cannot produce enough alveoli surfactant to prevent lung collapse so they have to breathe extremely strenuously

Question 5

What is boyle’s law?

Answer 5

At any constant temperature the pressure exerted by a gas varies inversely with the volume of the gas

Question 6

What are the two forces that hold the lungs to the chest wall?

Answer 6

The cohesive force of the intrapleural fluid

Negative intrapleural pressure

Question 7

What is tidal volume?

Answer 7

Volume of air entering or leaving the lungs during a single breath

Question 8

What is inspiratory reserve volume?

Answer 8

Extra volume of air that can be maximally inspired over and above the typical resting tidal volume

Question 9

What is inspiratory capacity?

Answer 9

Maximum volume of air that can be inspired at the end of a normal quiet expiration

Question 10

What is expiratory reserve volume?

Answer 10

Extra volume of air that can be actively expired by maximal contraction beyond the normal volume of air after a resting tidal volume

Question 11

What is residual volume?

Answer 11

Minimum volume of air remaining in the lungs even after a maximal expiration

Question 12

What is functional residual capacity?

Answer 12

Volume of air in lungs at end of normal passive expiration

Question 13

What is vital capacity?

Answer 13

Maximum volume of air that can be moved out during a single breath following a maximal inspiration

Question 14

What is total lung capacity?

Answer 14

Maximum volume of air that the lungs can hold

Question 15

What is forced expiratory volume in one second? (FEV1) (Dynamic volume)

Answer 15

Volume of air that can be expired during the first second of expiration in an FVC (Forced Vital Capacity) determination

Question 16

What is pulmonary compliance?

Answer 16

The measure of effort that has to go into stretching the lungs upon inspiration

Question 17

What can decrease pulmonary compliance?

Answer 17

Pulmonary fibrosis
Pulmonary oedema
Lung collapse
Pneumonia
Absence of surfactant

Question 18

What can increase pulmonary compliance?

Answer 18

Emphysema

Question 19

What is pulmonary ventilation?

Answer 19

The volume of air breathed in and out per minute

Question 20

What is alveolar ventilation?

Answer 20

The volume of air exchange between the atmosphere and alveoli per minute

Question 21

What are the 4 factors that affect the rate of gas exchange across alveolar membrane

Answer 21

1. Partial pressure gradient of O2 and CO2
2. Diffusion coefficient
3. Surface area
4. Membrane thickness

Question 22

What is Dalton’s law?

Answer 22

The sum of the partial pressures of each individual component in the gas mixture

Question 23

What is ficks law?

Answer 23

The amount of gas that moves across a membrane is proportional to the area of the membrane but inversely proportional to its thickness

Question 24

What is Henry’s law?

Answer 24

The amount of a given gas dissolved in a given type and volume of liquid at a constant temp is proportional to the partial pressure of the gas in equilibrium with the liquid

Question 25

How is oxygen transported in the blood?

Answer 25

Bound to haemoglobin (most)

Dissolved in solution (very little)