Past Exam Question
Remember this
was an A4 sheet!
So your answer
should be approx
half!
Ventilation - Inspiration
External intercostals contract
Lung volume
increases
Internal intercostals relax
Ribs pulled up and out
Diaphragm flattens
Atmospheric pressure greater
Lung pressure less
INSPIRATION – air forced into
lungs
Ventilation - Expiration
Internal intercostals contract
Lung volume
decreases
External intercostals relax
Ribs move down and in
Diaphragm relaxes into
‘dome’
Lung pressure greater
Atmospheric pressure less
EXPIRATION – air forced out of
lungs
Label the Lungs
Tuberculosis
Bacteria inhaled by person not immune
to it
Bacteria start to reproduce in upper lung
where plenty of oxygen
Usually in young
children
Primary
Infection
Immune system responds, phagocytes
arrive and ingest bacteria
Lymph nodes that drain area of lungs
become inflammed and enlarged –
Post-Primary Infection (may not
happen)
In healthy, more
resistant people
Few symptoms and the infection is
controlled, but some bacteria remain
Many years later bacteria re-emerge in
a second infection
More difficult to control. Lung tissue
damaged, scar tissue forms
Lung tissue and blood coughed
up,without treatment can fatally spread
throughout body
Lung Structure
Structure
Trachea
Bronchi
Bronchioles
Alveoli
Features
• Supported by c-shaped rings of cartilage
• Lined with cilliated epithelial cells to sweep mucus up to
throat
• Goblet cells produce mucus to trap dirt & microbes
• Larger branches supported by cartilage, less in smaller
• Lined with cilliated epithelial cells to sweep mucus up to
throat
• Goblet cells produce mucus to trap dirt & microbes
• Walls are made of muscle and epithelial cells
• Muscle allows them to constrict to control air flow to
alveoli
• Tiny air sacs (100-300μm in diameter)
• Lined with epithelial cells
• Membrane is gas exchange surface
• Contain collagen and elastic fibres (stretch and spring
back)
TB Exam Question
(b) After 4 minutes of exercise, the breathing rate was 20 breaths per minute.
Explain how you could use this information and the graph to calculate tidal
volume.
(c) When a person starts to breathe out, the percentage of oxygen in the air
first exhaled is the same as the percentage of oxygen in the atmospheric air.
Explain why.
Answers
(a) Immediate/rapid increase, steady rise and plateau clearly
identified; Ignore references to rest period if clearly
identified as such
1
(b) Find value of pulmonary ventilation from graph / 26-28;
Divide by breathing rate/20;
2
(c) Air is from nose/trachea/bronchi/not been in alveoli/dead
space; Gas exchange/diffusion only in alveoli / not in these
structures;
2