Mechanics of Breathing

Question 1

Name the two pleural membranes

Answer 1

• parietal pleura

- visceral pleura

Question 2

How is negative pressure in the pleural space maintained

Answer 2

the recoil of the lungs and chest wall away from each other

cohesive force arises from interaction between pleural membranes and fluid (like glass slides stuck together with water)

Question 3

What muscles are used in inspiration

Answer 3

• diaphragm

- external intercostals

Question 4

What muscles are used in expiration

Answer 4

• abdominal muscles

- internal intercostals

Question 5

What is asthma

Answer 5

the over-reactive constriction of bronchial smooth muscle

Question 6

What makes expiration difficult in asthma

Answer 6

the airways constrict even further, creating thh wheezing sound

Question 7

What is pneumothorax

Answer 7

• presence of air in the interpleural space
• becomes atmospheric pressure
• lung/chest cohesive force lost
• lung collapses as it is able to recoil

Question 8

What is intra-thoracic/alveolar pressure

Answer 8

pressure inside the thoracic cavity (+ive/-ive)

Question 9

What is intra-pleural pressure

Answer 9

pressure inside the pleural cavity (always -ive)

Question 10

What is transpulmonary pressure

Answer 10

alveolar minus intrapleural (always +ive)

Question 11

How do the abdominal muscles aid in expiration during severe respiratory load

Answer 11

they contract and reduce abdominal volume, causing abdominal organs to push the diaphragm into the resting position, thereby reducing thoracic volume