The Mechanics Of Breathing

Question 1

What are some of the features of lung compliance?

Answer 1

The stretchiness of the lungs are known as their compliance, and higher compliance means that the lungs are easier to stretch which can be increased by elastase in COPD, and lower compliance means that the lungs are more difficult to stretch, and these can be decreased by fibrosis after exposure to asbestos

Question 2

What is the elastic recoil of the lungs due to?

Answer 2

Elastic tissues of the airways, and surface tension of the fluid lining alewoli

Question 3

What is the importance of surfancant?

Answer 3

It is used to reduce the surface tension, as the higher the surface tension the harder the alveoli are to stretch due to the fluid that they are lined with, and surfactant is used to reduce the interactantions between the fluid molecules

Question 4

What is laplaces law?

Answer 4

Pressure is (2 x surface tension)/ radius,

Question 5

What is the law of bubbles?

Answer 5

If a big bubble is connecting to a small bubble, the air will flow from the larger bubble into the smaller bubble, therefore a smaller bubble will collapse into a large bubble

Question 6

What is the relvanve of laplaces law to the alevoli?

Answer 6

If the law of bubbles applied, big alevoli would eat the smaller ones, and everything would collapse but this does not happen in the lungs

Question 7

How do the lungs avoid laplaces law?

Answer 7

The surfactant is less effective in the little alveoli as they increase in size, the surface tension also increases ensuring that the alveol remain at a high pressure,and stops them collapsing- it equalises the pressure between the different size alveoli.

Question 8

What are some of the features of respiratory distress syndrome?

Answer 8

Babies born prematurely and are producing too little surfacant (is usaully starts to be produced at 34 weeks) and therefore the lungs are very stiff and therefore there are few and large alevoli, and therefore you need to use a low pressure ventilitator in children

Question 9

Why do the airways not have huge resistant (posielles law)

Answer 9

Each brach in the airway increases the number of airways in parallel, and this compensates for the increase in resistance as the air passes down