Anatomy of chest wall and the mechanics of breathing

Question 1

What is Boyle’s law

Answer 1

Boyle’s Law states that the pressure exerted by a gas is inversely proportional to to its volume (P a 1/V).

Question 2

State Dalton’s law

Answer 2

Dalton’s Law states that the total pressure of a gas mixture is the sum of the pressures of the individual gases.

Question 3

Describe Charle’s law

Answer 3

Charles Law states that the volume occupied by a gas is directly related to the absolute temperature (v a T)

Question 4

What is Henry’s law?

Answer 4

Henry’s Law states that 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

What encloses the lower respiratory system?

Answer 5

Thoracic cage

Question 6

What attaches the lungs to the inner surface of the rib-cage?

Answer 6

Nothing

They are stuck together (or at least the pleura are held together) by the intrapleural fluid

Question 7

What is Pleurisy?

Answer 7

Inflammation of the pleura

Question 8

What is it called when the two pleural membranes separate from each other?

Answer 8

Pneumothorax

Question 9

What muscles are used for normal inspiration?

Answer 9

Diaphragm and external intercostals

Question 10

What accessory muscles can be used for inspiration if needed?

Answer 10

Scalene and sternocleidomastoid muscles in your neck

Pec major & minor

Latissimus dorsi

Serratus anterior, posterior superior

Question 11

What muscles are used for expiration at rest?

Answer 11

None

Expiration is normally passive

Question 12

What muscles can be used for forced expiration?

Answer 12

Internal intercostals & abdominal muscles

Question 13

Describe how inspiration works

Answer 13

Diaphragm and Ext intercostals contract causing the volume of the lungs to increase

Greater volume = lower pressure (Boyle’s law)

Lower pressure inside the lungs compared to outside pressure causes air to move into the lungs

Question 14

In what two ways do individual ribs move during inspiration, that causes an increase in the volume of the thoracic cage?

Answer 14

‘Pump handle motion’ increases anterior-posterior dimensions of the rib cage

‘Bucket handle motion’ increases lateral dimensions of the rib cage

Question 15

What is the normal intrapleural pressure?

Answer 15

-3 mmHg

Question 16

What creates the intrapleural pressure?

Answer 16

Elastic recoil of the chest (outward) acting against the elastic recoil of the lungs (inward)

Question 17

If intrapleural pressure is the same as atmospheric pressure, whats happened?

Answer 17

Pneumothorax

Question 18

What is the Transpulmonary pressure?

Answer 18

difference between alveolar pressure and intra-pleural pressure. ALWAYS positive (in health) because intrapleural pressure is always negative. PT = PA – Pip.

Question 19

When is alveolar pressure most positive?

Answer 19

Expiration

Question 20

When is intrapleural pressure greatest and why?

Answer 20

After expiration (but before inspiration)

This is when the volume of air in your lungs is lowest, so the force of elastic recoil of the lungs is highest