Anatomy of chest wall and mechanics of breathing

Question 1

Boyle’s Law

Answer 1

The pressure exerted by a gas is inversely proportional to to its volume (P a 1/V).

Question 2

Dalton’s Law

Answer 2

The total pressure of a gas mixture is the sum of the pressures of the individual gases.

Question 3

Charles Law

Answer 3

The volume occupied by a gas is directly related to the absolute temperature (v a T)

Question 4

Henry’s Law

Answer 4

The amount of gas dissolved in a liquid is determined by the pressure of the gas and it’s solubility in the liquid.

Question 5

How many lobes does the right lung have?

Answer 5

3

Superior, Middle and Inferior

Question 6

How many lobes does the left lung have?

Answer 6

2

Superior and Inferior

Question 7

What covers the lungs and interior of the thorax?

Answer 7

They are covered by pleural membranes between the surfaces of which is an extremely thin layer of intrapleural fluid.

Question 8

What is between the visceral pleural membrane and parietal pleural membrane?

Answer 8

Pleural fluid

Question 9

What is pleurisy

Answer 9

Inflammation of the pleura.

The pleura are two thin sheets of tissue that separate the lungs and ribcage.

Question 10

What muscles does inspiration use?

Answer 10

External muscles, Diaphragm, sternocleidomastoids and scalenes.

Question 11

What muscles does expiration use?

Answer 11

Internal intercostal and abdominal muscles.

Question 12

What is Asthma?

Answer 12

Over-reactive constriction of bronchial smooth muscle.

Increases resistance, expiration difficult.

Question 13

Pneumothorax

Answer 13

Lung collapses to unstretched size.
The rib cage expands slightly.
If the sealed pleural cavity is opened to the atmosphere, air flows in.

Question 14

Intra-thoracic (Alveolar) Pressure (PA)

Answer 14

Pressure inside the thoracic cavity, (essentially pressure inside the lungs). May be negative or positive compared to atmospheric pressure.

Question 15

Intra-pleural Pressure (Pip)

Answer 15

Pressure inside the pleural cavity

ALWAYS NEGATIVE in healthy lungs

Question 16

Transpulmonary pressure (PT)

Answer 16

Difference between alveolar pressure and intra-pleural pressure. ALWAYS POSITIVE in healthy lungs because Pip is always negative.
PT = PA – Pip.

Question 17

What happens at the end of an unforced expiration?

Answer 17

Patm= PA, no air is flowing, and the dimensions of the lungs and thoracic cage are stable as the result of opposing elastic forces. The lungs are stretched and are attempting to recoil, whereas the chest wall is compressed and attempting to move outward. This creates a subatmospheric intrapleural pressure and hence a transpulmonary pressure that opposes the forces of elastic recoil.

Question 18

What does airway resistance determine?

Answer 18

Airway resistance determines how much air flows into the lungs at any given pressure difference between atmosphere and alveoli. The major determinant of airway resistance is the radii of the airways.