19. The rings of cartilage
keep the trachea open
at all times
During
swallowing.
During exhaling.
20. Three things happen to the air
breathed in as it passes through the
nasal passages:
Cilia Mucus
Cell membrane
21. It is better to breathe through the
nose rather than the mouth. Why?
22. What prevents food from
entering the trachea?
Epiglottis closes
the trachea .
trachea
23. Sequence air takes to enter the
lungs:
2. pharynx 1. nasal passages
4. trachea 3. larynx
lung
5. bronchi
6. bronchioles
7. alveoli
24. The lungs are placed in an
air-tight chamber
What happens to the lungs if air enters this
chamber?
Lung collapses
25. Fun Facts
At rest, the body takes in and breathes out about 10
liters of air each minute.
* The right lung is slightly larger than the left.
* The highest recorded "sneeze speed" is 165 km per
hour.
* The capillaries in the lungs would extend 1,600
kilometers if placed end to end.
* We lose half a liter of water a day through breathing.
This is the water vapor we see when we breathe
onto glass.
* A person at rest usually breathes between 12 and 15
times a minute.
* The breathing rate is faster in children and women
than in men.
33. CHANGES IN THE COMPOSITION OF
BREATHED AIR
Gas Inhaled % Exhaled %
Oxygen 21 16
Carbon dioxide 0.03 4
Nitrogen 79 79
Water vapour variable saturated
Why is exhaled air always saturated
with water vapour?
37. Question: SEP, 2008
a) Explain why humans breathe out:
i) more carbon dioxide than is breathed in, (2)
A waste product that is made all the time by
respiration.
ii) as much nitrogen as is breathed in. (2)
Not used by the body.
38. b) Compare the amount of water vapour in
inhaled and exhaled air. (2)
More present in exhaled air due to
evaporation from film of moisture inside
alveoli.
39. Question: MAY, 2010
Draw a clear well labelled diagram showing
how gaseous exchange takes place in the
alveolus. (4)
40. Fig. 4 A small part of a human
lung.
Give TWO features of
alveoli that aid
diffusion of gases.
1. Thin epithelium
2. Dense capillary network
3. Provide a large surface area
44. 1. NICOTINE
increases heart rate and blood pressure
person becomes
addicted
45. 2. CARBON MONOXIDE
combines with haemoglobin in red blood
cells so reducing the level of oxygen in the
blood
46. 3. TAR
a black sticky material that
remains in the lungs
47. 3. TAR
contains over a thousand chemicals,
some of them are carcinogens
(substances that cause cancer)
48. Some effects of cigarette
smoke:
1. Irritate the membrane lining the upper
respiratory tract.
2. Cilia stop beating.
3. Extra mucus forms in the trachea and
bronchi causing ‘smoker’s cough’.
49. Non- smoker Smoker
Note more mucus present
compared to a non-smoker.
50. 4. Smoking weakens the walls of the alveoli
and repeated coughing can destroy some of
them.
This breakdown of alveoli is called emphysema.
51. Question: MAY, 2007
Why do people who suffer from emphysema
become breathless on minimal physical activity
e.g. walking upstairs? (3)
Emphysema results in a reduction in lung
volume.
Less surface area to absorb oxygen.
Person cannot produce enough energy.
52. Question: MAY, 2010
Explain why:
i) patients suffering from emphysema absorb less
oxygen; (3)
Emphysema is a condition caused by the
deterioration of the alveolar wall. This decreases
the surface area for absorption therefore there is
decreased gaseous exchange (less oxygen uptake).
Award half a mark if they mention alveoli burst.
53. Question: MAY, 2010
Explain why:
ii) emphysema patients tend to hyperventilate
(rapid breathing); (3)
Emphysema patients try to compensate for the
decrease oxygen uptake by taking quick rapid
breaths. This increases oxygen concentration in
the lungs and therefore increases oxygen
absorption.
54. Question: MAY, 2010
Explain why:
iii) emphysema patients are more prone to
pulmonary infections such as bacterial
bronchitis. (3)
Emphysema is mainly caused by smoking.
Cigarette smoke stops the cilia in the breathing
system from beating, leading to an accumulation
of mucus and microbes in the lungs. Microbes
remain in lungs and can infect , bringing about
pulmonary infections.
55. 5. Babies born to mothers who smoke:
are generally lighter than babies born
to non-smoking mothers
are at a risk of premature birth
56. Question: SEP, 2011
Explain why pregnant females are
encouraged to avoid smoking. (3)
Higher risk for miscarriages.
Higher risk for premature birth.
Less oxygen reaches embryo – baby is
born smaller than average.
Chemicals in smoke affect the brain of
the embryo and baby is born mentally
retarded.
57. What is ‘passive smoking’?
When people
breathe in the
smoke from other
people’s
cigarettes.
59. Examples of lung diseases:
Asthma
Lung cancer
Bronchitis
Emphysema
60. Examples of lung diseases:
Pneumonia Normal alveoli
[inflammation of alveoli]
Pneumonia
61.
62. Feature Function
1) alveoli present a large
to absorb oxygen
surface area
to allow oxygen to diffuse
2) alveolar lining is very thin
into the blood easily
3) alveolar surface is moist to allow oxygen to dissolve
4) a dense capillary network to pick up and transport
surrounds the alveoli oxygen
5) a mechanism to renew the to keep a high concentration
air in contact with the gradient between the alveoli
alveoli and the blood
