Gas ExchangeLesson ObjectivesBy the end of this lesson:• MUST explain how gases are exchanged in the alveoli.

(Grade C).• SHOULD use evidence from the investigation to justify the

symptoms of emphysema. (Grade B).• COULD create an informative and persuasive argument that

fully details the changes that take place in emphysema and justify the effects on physiology. (Grade A).

Keywords:alveoli diffusion

surface area emphysema elasticity

recoil cyanosis chronic

What’s it like to have

emphysema?

Final Product• You are a qualified G.P. and you have

a patient that has been diagnosed with a mild case of emphysema. The patient is a smoker and is reluctant to stop because they think it’s cool. Create an informative and persuasive argument to present to your patient next time you see them.

Amy had early stage emphysema and an

irregular heartbeat, and was been warned that she

would have to wear an oxygen mask unless she

stopped smoking.

Emphysema

Our big question

How can we justify the symptoms of

emphysema using scientific evidence?

Lung TissueNormal Emphysema

What are the

differences?What are

the effects?

Investigating Surface Area of Lung Tissue

The agar blocks represents lung tissue.

The acid makes the ‘tissue’ change colour.

ResultsNumber of pieces Time taken to diffuse (secs)

How can we justify the symptoms of

emphysema using scientific evidence?

The surface-area-to-volume ratio changes with increasing size

© Pearson Education Ltd 2008This document may have been altered from the original

Amy Winehouse and Emphysema

What enquiry questions arise as a result of reading this article?

http://www.foxnews.com

/story/2008/06/23/amy-winehouse-emphysema-at-24-very-rare-experts-say/

•Mouth/Nasal Cavity •Trachea •Bronchi

•Bronchioles•Alveoli

The Structure of the Lungs

Emphysema Symptoms• Shortness of breath• Cyanosis – bluish skin coloration• Chronic cough

AlveoliBronchiole

OxygenCarbon dioxide

Capillary

Gas Exchange at the Alveoli

AlveoliBronchiole

OxygenCarbon dioxide

CapillaryAlveoli

Bronchiole

Carbon dioxide

OxygenCapillary

Gas Exchange at the Alveoli

What’s Happening inside?

The Cause?

Information Hunt• Now go on an information hunt to

find information to help you prepare for your case

The Gas Exchange SurfaceIn order to have efficient diffusion taking place a gas exchange surface must have:

Large surface area Short distance of diffusion A large concentration difference on

opposite sides of the surface

In the human lungs the large surface area is achieved by having a huge

number of very small alveoli.

Emphysema• One in 5 smokers will develop the lung disease called

emphysema.• This disease takes a long period of time to develop

(chronic disease) – typically 20 years or more. It is not usually diagnosed until the lungs have been irreversibly damaged.

• Healthy lungs contain large quantities of elastic tissue made of the protein elastin. One effect of cigarette smoke is to stimulate white blood cells to release protein-digesting enzymes that gradually break down the walls of the alveoli leaving large open spaces.

EmphysemaOne enzyme targets elastic tissue in the lungs. In emphysematous lungs the elastin has become permanently stretched. This loss of elasticity reduces the ability of the lungs to recoil after breathing in and so air cannot be forced out of the alveoli effectively. The surface area of the alveoli is reduced and they sometimes burst. Very little gas exchange can take place across the gas exchange surface as a result.

Emphysema SymptomsSHORTNESS OF BREATH• Loss of elasticity – ventilating lungs

more difficult, more difficult to exhale air, hard to maintain diffusion gradient.

• Smaller alveolar surface area results in lower levels of oxygen, so patient tries to breathe faster.

Emphysema SymptomsCHRONIC COUGHReflex reaction in attempt to remove damaged tissue and mucus (which cannot be removed due to inactive/destroyed cilia).BLUISH SKIN COLOURATION (cyanosis)Reduced intake of oxygen into blood as a result of poor diffusion in the alveoli.

Final Product• You are a qualified G.P. and you have

a patient that has been diagnosed with a mild case of emphysema. The patient is a smoker and is reluctant to stop because they think it’s cool. Create an informative and persuasive argument to present to your patient next time you see them.