Lecture notes
Respiratory System 3: Compliance and Pulmonary Circulation
- Module
- Systems of the Body 2
- Institution
- University Of Bristol (UOB)
A description of compliance and the pulmonary circulation around the lungs.
[Show more]
Content preview
COMPLIANCE AND PULMONARY CIRCULATIONCompliance = measure of elasticity of the lungs: the ease with which
they can be inflated.
Defined as change in lung volume that results from given change in
transpulmonary pressure (Palv – Pip).
Increased compliance: larger change in lung volume for a given increase in
transpulmonary pressure.
Lung Compliance depends on:
1. Elasticity of lungs
2. Surface Tension of fluid lining of alveoli
1. Elasticity of Lungs
Lungs are elastic due to elastic fibres in c.t.
Forces exerted by these elastic fibres generally oppose lung
expansion because as lung stretches, fibres tend to recoil.
2. Surface Tension
Caused by air-liquid interface formed by the thin layer of fluid lining
the surface of the alveoli.
Law of Laplace = air pressure (P) within alveolus directly
proportional to surface tension (T) and inversely proportional to
alveolus raidus. P = 2T/r
Therefore, if you have a small and a large alveolus both with the
same surface tension, the smaller alveolus will have a higher
pressure compared to the larger alveolus according to the Law of
Laplace.
Gas will then transfer from the smaller alveolus to the larger
alveolus and the smaller one will collapse. This will continue and the
lung will become unstable.
Therefore to overcome this: we have surfactant:
Produced by Type II pneumocytes
Decreases surface tension; therefore, allowing pressure to be
equalized in the large and small alveoli using Law of Laplace.
Increases compliance of the lungs and reduces work of breathing.
Stabilises alveoli.
Surfactant deficiency = Associated with premature births and
newborn respiratory distress syndrome.
Changes in Compliance:
INCREASES:
Emphysema – Less elastic tissue, easier to stretch, increases airway
resistance.
Aging
DECREASES:
Fibrosis – stiff, thickening of wall between alveoli and capillaries,
can’t pull out lungs , decreased FVC.
Deficiency of Surfactant
Pulmonary Oedema
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller harrykane. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for £2.99. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
67474 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy revision notes and other study material for 14 years now