Chapter : 11
Gas exchange
In humans
Made by
Alamin Bakri
Intercostal muscles
• External intercostal
• Internal intercostal
ribs
Function of cartilage in trachea
• Support the trachea and keep it open
• Prevent it from collapsing when there is no air
in it
Gas exchange surface
Alveoli
Its an air sac in lungs where gas exchange
happens
Features of gas exchange surface
• large surface area
• Thin walls
• Good blood supply
• good ventilation with air
Role of ribs ,intercostal muscles
and diaphragm during breathing
During inspiration During expiration
1) External intercostal muscles 1) External intercostal muscles
contract pulling rib cage relax
upward and out ward 2) Internal intercostal muscles
2) Internal intercostal muscles contract pulling the ribcage
relax backward and inward
3) Muscles of diaphragm 3) Muscles of diaphragm relax
contract pulling diaphragm bring it back to its dome
downward shape
This increases the volume of This decreases the volume of
the thorax and decreases the the thorax and increases the
pressure inside causing air pressure inside causing air to
rush into the lungs be squeezed out
Investigating CO2 composition
between expired and inspired air
• Limewater is used as indicator
• When CO2 is bubbled into limewater
It turns form clear cloudy
The effect of physical activity on
breathing rate and depth
• During any physical activity the muscles uses oxygen
for respiration to release energy
• As activity increases cell needs more energy
therefore more oxygen
• As activity increases this will increase the breathing
rate and depth to get more oxygen for the cells
Exercise and Carbon dioxide
concentration in blood
• During physical activity large amount carbon
dioxide is released into the blood by
respiration
• This lowers the blood PH which is detected by
the brain
• Brain sends signals to breathing system to
increase rate and depth of breathing for
carbon dioxide to diffuse out of the blood
through the alveoli
Role of cilia and goblet cells in
protecting the breathing system
• Goblet cells secret mucus in nose trachea and
bronchi
Mucus traps dust particles and pathogens to
entering to the alveoli
• Then the mucus is pushed upward by hair like
structures called cilia
Its pushed to the throat to not block the lungs
and prevent respiratory infection
