6.8 - Exchange of gases in the lungs Flashcards
Where is the site of gas exchange in mammals
- the epithelium of the alveoli
Describe the structure of the alveoli
- minute sacs (100-300 micrometers in diameter)
- Situated in the lungs
How is the alveoli adapted for its role
- Red blood cells are slowed as they pass through pulmonary capillaries, allowing more time for diffusion
- The distance between the alveolar air and red blood cells is reduced as the red blood cells are flattened against the pulmonary capillary walls
- The walls of alveoli and capillaries = very thin and therefore has a short diffusion pathway
- Alveoli and pulmonary capillaries have a very large SA
- Breathing movements constantly ventilate the lungs, and the action of the heart constantly circulates blood around the alveoli = BOTH ENSURES: steep concentration gradient that is maintained for gas exchange
- Blood flow through the pulmonary capillaries maintains a concentration gradient
State a correlation shown in the diagram
Correlation between the incidence of lung cancer in men and number of cigarettes smoked per day
Explain why the information provided does not show a casual relationship with the correlation you have identified
- There is no experimental evidence in the data provided to show that smoking causes cancer
- Hence there is no causal link between the 2 variables
List 5 factors associated with lung disease
- smoking
- air pollution
- genetics
- infections
- occupation
Use the diagram to determine what % of non-smokers are likely to survive to age 80
Anywhere from between 50-60%
Calculate how many times greater is the likelihood of a non-smoker living to age 70 than someone who smokes over 25 cigarettes a day
- 2x
- around 80% of non-smokers live to age 70
- whereas around 40% of people who smoke more than 25 cigarettes a day live to 70
How is lung function measured
- Forced Expiratory Volume (FEV)
- it is the volume of air that can be forcibly blown out in 1 second, after full inspiration
Suggest how pulmonary fibrosis might effect FEV and explain why
- FEV will be lower/less because to achieve a normal FEV, the lungs must be elastic
- fibrosis reduces elasticity and makes it difficult to breathe out
Suggest some restrictions that have been put in place in order to reduce lung disease
- restrictions on production of cigarettes = less tobaccos smoked = less incidences of lung disease
- banning smoking in public spaces = reduces opportunity for smokers to smoke = less tobacco smoked = less incidences of lung disease
- ban on tobaccos advertising = less encouragement for people to smoke tobacco, especially younger people
- age restrictions on buying tobacco = prevent young people starting to smoke and becoming addicted
- plain packaging = reduces appeal of tobacco
- health warnings on packets = educate/persuade people on the dangers of smoking = aims to stop smoking altogether
What is the risk factors associated with emphysema
Smoking
—> impossible to diagnose until lungs are irreversibly damaged
What are the consequences of emphysema
- elastin becomes stretched out so air cannot be forced out of lungs
- SA of alveoli is reduced reduced — very little gas exchange
- breathlessness due to lack of oxygen
What are the symptoms of emphysema
- shortness of breath (due to loss of elasticity and reduced oxygen levels)
- chronic cough (body trying to remove damaged tissue + cilia is destroyed)
- bluish skin colouration (low oxygen levels)
What are the risk factors associated with asthma
- stimulated by allergens (e.g. pets, pollution, cold air, etc)
- allergens cause WBC which produce histamines
