Respiration & Breathing
Respiration
What is respiration?
It is the release of energy from food
substances in living cells.
respiration
 Sugar is oxidised to release energy, carbon
dioxide and water are formed.
 Equation:
 sugar + oxygen




energy + carbon dioxide + water
(i) sugar comes from food
(ii) oxygen comes from air
(iii) carbon dioxide is excreted thru’ lungs
(iv) energy is used for life processes or lost
as heat (keeps body warm).
Breathing system
To move air in and out of lungs for
gaseous exchange.
Gaseous exchange
Diffusion of oxygen from lungs into blood.
Movement of carbon dioxide from blood
into lungs.
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Breathing System - Nasal Passage
nasal cavity
epiglottis
voice box
windpipe
Path taken by air to lungs.
1 Air passes through nasal passages, wind
pipes and alveoli.*
2 Wind pipes are kept open by cartilage
rings.*
3 Gaseous exchange takes place in alveoli.*
Air Sacs - Alveoli
How air enters and leaves the lungs
The Rib cage
Breathing
1 Chest expands to inhale
2 Chest contracts to exhale
Is breathing voluntary?
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Inhalation
Exhalation
Compare and Contrast
The Rib Cage
The Bell jar
Composition of air in the lungs
Gas
Oxygen
Carbon dioxide
Nitrogen
Water vapour
Percentage in Percentage in
inhaled air
exhaled air
21%
16%
0.04%
4%
79%
79%
a little
a lot
Experiment to show that
exhaled air contains
Carbon Dioxide
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Indicator used to test for presence
of Carbon Dioxide
 calcium hydroxide
 (lime water)
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To test for presence of Carbon dioxide
in Expired air
Gaseous exchange in alveoli
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Pulmonary Circulation
Respiratory System
Air Sacs
Gaseous Exchange
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Respiratory System
Return
Exercise- Breathing Hard
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Recovery period
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Energy
What is energy needed for?
• Animals - for movement, sending messages
through nerves, transport of food, keeping warm.
• Plants - for taking up minerals from soil, opening
and closing of stomata, and transport of food.
• All organisms - for growth, cell division, and
moving molecules against a concentration gradient
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Respiration in animal and plant
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Gills of fish
 Fish breathe with gills.
Gill
cover
 Gills are feather-like
structures with a rich
supply of blood vessels.
 Gills are found under the
gill covers of fish.
How a fish breathes in …
Water enters
the mouth of the fish …
How a fish breathes in …
Water enters
the mouth of the fish …
Gills
… and flows over the gills.
Oxygen passes through the walls
of the blood vessels and into the blood.
How a fish breathes out …
Carbon dioxide passes
through the walls
of the blood vessels
and dissolves in the water.
How a fish breathes out …
Carbon dioxide passes
through the walls
of the blood vessels
and dissolves in the water.
Water with dissolved
carbon dioxide flows out
from under the gill
cover.
Dolphins and whales breathe …
blowhole
… through special
nostrils called
blowholes on top of
their heads.
blowhole
How do different animals breathe?
 Lungs
eg. Man, whale, seal, bat, snake, dog, cow
 Moist skin
eg. Frogs, toads, salamander, earthworm
 Gills
eg. Fish, tadpole, mudskipper
 Breathing tube
eg. Wriggler, water stick insect
 Breathing holes
eg. Ant, dragonfly
Respiratory System in Plants
underside of a leaf
stoma
• Plants exchange
gases with their
surroundings
through the stoma.
My Pals are Here!
Science 4B © 2003
You are reminded that under the Copyright Act, it is an offence to reproduce or copy any part of this presentation without permission from Times Media Private Limited.
In the day
At night
During photosynthesis
carbon dioxide
oxygen
During respiration
During respiration
oxygen
carbon dioxide
carbon dioxide
oxygen
My Pals are Here! Science 4B © 2003 Times Media Private Limited
You are reminded that under the Copyright Act, it is an offence to reproduce or copy any part of this presentation without permission from Times Media Private Limited.
Respiration and
Photosynthesis
Which is faster?
What does it depend
on?
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