Physiology

Question 1

Define Internal Respiration

Answer 1

Intracellular mechanism which consumes O2 and produces CO2.

Question 2

Define External Expiration

Answer 2

Sequence of events that lead to the exchange of O2 and CO2 between the external environment and the cells of the body.

Question 3

Define Ventilation

Answer 3

The mechanical process of moving gas in and out of the lungs.

Question 4

Define Boyle’s Law

Answer 4

At any constant temperature, the pressure exerted by a gas varies inversely with the volume of the gas. (E.g. As the volume of a gas increases the pressure exerted by the gas decreases).

Question 5

Define Atmospheric Pressure

Answer 5

Pressure caused by the weight of the gas in the atmosphere on the Earth’s Surface. Normally 760 mmHg at sea level.

Question 6

Define Intra-Alveolar Pressure

Answer 6

Pressure within the lung alveoli. 760 mmHg when equilibrated with atmospheric pressure.

Question 7

Define Intra-Pleural Pressure

Answer 7

Pressure exerted outside the lungs within the pleural cavity. Usually less than atmospheric pressure.

Question 8

Define Transmural Pressure Gradient

Answer 8

Difference in pressure gradients between either;

Alveoli and Intra-pleural pressure = transpulmonary pressure.

Atmospheric and Intra-pleural pressure = Pressure across thoracic wall.

Question 9

Define Alveolar Surface Tension

Answer 9

Attraction between water molecules at liquid-air interface which produces a force that resists the stretching of the lungs. If the alveoli were lined with water along, the surface tension would be too strong causing the alveoli to collapse.