Anatomy of Chest Wall and Mechanics of Breathing

Question 1

Boyle’s Law

Answer 1

Pressure exerted by a gas is inversely proportional to its volume
Increased volume => decreased pressure

Question 2

Parietal pleural membrane

Answer 2

Lines ribs

Question 3

Visceral pleural membrane

Answer 3

Lines lungs

Question 4

Pleural cavity

Answer 4

Filled with intrapleural fluid - acts as a lubricant, allows membranes to glide across each other

Question 5

Pleurisy

Answer 5

Inflammation of the pleura

Question 6

Inspiration

Answer 6

External intercostal muscles and diaphragm

Lower pressure, lungs expand, draws air into the lungs

Question 7

Expiration

Answer 7

Passive at rest, but uses internal intercostal and abdominal muscles during severe respiratory load

Question 8

Pneumothorax

Answer 8

Presence of air in the pleural space

Question 9

Haemothorax

Answer 9

Presence of blood in the pleural space

Question 10

Haemo-pneumothorax

Answer 10

Presence of both blood and air in the pleural space

Question 11

Pyothorax

Answer 11

Accumulation of pus in the pleural space

Question 12

Intra-thoracic (alveolar) pressure (P A)

Answer 12

Pressure inside the thoracic cavity

May be positive OR negative compared to atmospheric pressure

Question 13

Intra-pleural pressure (P ip)

Answer 13

Pressure inside pleural cavity

Always negative

Question 14

Transpulmonary pressure (P T)

Answer 14

Difference between alveolar and intrapleural pressure
Always positive
P T = P A - P ip

Question 15

Pressure difference across the lungs

Answer 15

Transpulmonary pressure

Question 16

Asthma

Answer 16

Overreactive constriction of bronchial smooth muscle

Increases resistance, expiration difficult