Anatomy of the chest and mechanics of breathing

Question 1

mechanics of inspiration

Answer 1

• Diaphragm and external intercostal muscles contract which increases the volume of the thoracic cage
• pump handle and bucket handle movements of rib cage
• Pip becomes move negative
• Lungs expand
• Pa becomes sub atmospheric
• Air flows in

Question 2

Mechanics of expiration

Answer 2

• Inspiration muscle cease contracting
• Elastic recoil of the chest and lungs causes the thoracic cage to return to its normal levels
• Pa increases so air flows out

Question 3

Forced expiration

Answer 3

Internal intercostal muscles and the abdominal muscle contract to reduce the volume of the thoracic cage

Question 4

What gas rule do expiration and inspiration follow?

Answer 4

Boyles Law: Pressure is inversely proportional to volume.

Gases tend to move from an area of high pressure to an area of low pressure.

Question 5

What are the pleural membranes

Answer 5

1 bound to exterior lung surface- visceral
1 found to interior layer of ribs- parietal
Allow the lungs to stay bound to the rib cage
Pleural cavity contains pleural fluid

Question 6

Different pressures

Answer 6

Alveolar or intra-thoracic pressure: Pa- pressure inside thoracic cavity
Intra-pleural Pip- always negative
Intra-thoracic : Pa-Pip -always positive

Question 7

Changes in pressure during inspiration

Answer 7

In 2 seconds
Pa 0--(-1)--0 mmhg
Pip (-3)-- (-6) mmhg
Volume of air breathed in 
500 ml

Question 8

Changes in pressure during expiration

Answer 8

In 2 seconds 
Pa: 0--1--0 mmgh
Pip : (-6)--( -3) mmhg
volume of gas exhaled
500 ml

Question 9

Pneumothorax

Answer 9

Occurs when pleural cavity is pierced
The elastic recoil of the lung causes it to collapse
The elastic recoil of the rib cage pulls it out causing it to expand slightly
Pip goes from being negative to being close to Patm

Question 10

Bulk flow

Answer 10

F
proportional to Patm-Pa
inversely proportional to resistance

Question 11

pump movement and bucket handle movement

Answer 11

Pump movement: increases anterior-posterior rib cage

Bucket handle movement: increases lateral rib cage movement

Question 12

Which are the accessory muscles in inspiration and expiration

Answer 12

Inspiration: sternocleidomastoid muscle and the scalene
Expiration: Internal intercostal and abdominal muscle