Systems - Air & the Human Respiratory System

8/9/2019 Systems - Air & the Human Respiratory System

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2009 Marshall Cavendish International (Singapore) Private Limited


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Questions to think about

What is air

made upof?

What are the organs of the

human respiratory system,

and what are their functions? How do fish,

mammals and plants

take in oxygen and

give out carbondioxide?



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All mixed up!

Air is a mixture of gases.

About one-fifth of air is oxygen.

The remaining four-fifths are mostly madeup of nitrogen and a small amount of

carbon dioxide, water vapour and some

other gases.



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All mixed up!

oxygencarbon dioxide,

water vapour and

other gases

nitrogen



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All mixed up!

Oxygeno Most living things need oxygen to stay

alive.

o Living things take in oxygen in order tobreak down digested food to produceenergy in a process called respiration.

o Living things on land take in oxygenfrom the air around them.

o Animals and plants that live in wateruse oxygen that is dissolved in water.

o Animals living in the ground and rootsof plants use oxygen that is found inthe soil.



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All mixed up!

Oxygen

o Oxygen is also needed for burning.

oW

hen we light a candle, burn a piece of paperor set fire to wood, oxygen is used up.

o A continuous supply of fresh air rich in oxygen

is needed to keep things burning.



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All mixed up!

Nitrogeno Although nitrogen makes up four-

fifths of the air, this gas is notused by most living things.

o Only some bacteria living in thesoil are able to use nitrogen fromthe air around them.

o Plants must have nitrogen to live,but they are not able to usenitrogen from the air.

o Bacteria that live in the roots ofplants change nitrogen from theair that is in the soil, into a formplants can use.



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All mixed up!

Carbon dioxide, water vapour andother gases

o When living things respire or when things

burn, oxygen is used up and carbon dioxideis produced.

o Carbon dioxide is important to plants.

o During the day, plants use carbon dioxide

and water to make food in a process calledphotosynthesis.

o Oxygen is produced at the same time.



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Respiratory system

Breathing is the process of taking in airinto our bodies and giving it out again.

We breathe so that we can take inoxygen for respiration.

At the same time, carbon dioxide isformed.

Carbon dioxide is removed from ourbodies and released into the air when

we breathe out. The parts of a living thing that help it to

breathe form the respiratory system.

Different animals have different parts intheir respiratory systems.



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Human respiratory system

Lungs

o When you breathe in,

your ribs move out and

upwards.

o Yourdiaphragm, a thin

sheet of muscle moves

downwards.o This causes your chest

to become bigger.diaphragm

air



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Lungs

o As a result, air rushes

into your body through

yournose or your

mouth.

o Air that enters your

respiratory system iscleaned, warmed and

moistened.diaphragm

air



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Lungs

o The air then moves down

your windpipe.

o Your windpipe branches to

the left and right into two

smaller tubes.

windpipe



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Lungs

o Each of these tubes lead to

one of your two lungs.

o These tubes branch further

into tiny tubes that end in

balloon-like air sacs.



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Lungso The air sacs have a rich supply of

blood vessels.

o When the air you breathe inreaches your air sacs, oxygen

passes through the walls of the

sacs into the blood vessels.

o Your body then

carries the oxygento all parts of your

body.



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Lungs

o When you breathe out,

your ribs move in and

downwards.o This time, your diaphragm

moves upwards.

o This causes your chest to

become smaller and the airthat has carbon dioxide in

it, is forced out of your

lungs.diaphragm

air



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Animal respiratory system

Fish

o Fish breathe with their

gills.

o Gills are feather-like

structures with a rich

supply of blood

vessels.o They are found under

the gill covers of fish.

gills



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Fisho A fish makes use of the oxygen

that is dissolved in the wateraround it.

o When water enters the mouthof the fish and flows over itsgills, oxygen passes throughthe walls of the blood vesselsand into the blood.

o Oxygen is then carried by theblood to different parts of thefish.



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Fish

o Carbon dioxide passes

through the walls of the

blood vessels, dissolves in

the water and is carried

away as the water flows

out from under the gill

covers.



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Mammals living in water

o The whale and dolphin are

mammals that live in water.

o Just like fish, they stay inwater all the time.

o Like all mammals, the whale

and dolphin breathe through

lungs.o They need to come up to the

water surface to take in air,

otherwise they will drown.



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Mammals living in watero The whale and dolphin have

special nostrils called

blowholes on top of theirheads.

o During breathing, the whaleand dolphin only need to stickpart of their heads out of thewater to expose their blowholes

to the air.o A whale often blows through its

blowhole to get ride of waterthat has entered it.

blowhole of a dolphin

blowhole of a whale



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Plant respiratory systemPlant respiratory system

Like animals, plants alsoexchange gases with theirsurroundings.

The exchange takes placethrough tiny openings onthe surface of the leaves.

These tiny openings are

called stomata. One such opening is

referred to as a stoma.

stoma



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Plant respiratory systemPlant respiratory system

Stomata are usually

found on the underside

of leaves, away from

direct sunlight.

This is to prevent water

inside the plant from

evaporating throughthe stomata.

stoma



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Plant respiratory system

In respiration, plants use

oxygen from the air to

release energy from the

food they have made. Carbon dioxide is

produced in the process.

This process of

respiration takes place

all the time.

carbon

dioxide

oxygen

All the time



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Besides respiration,plants also carry outphotosynthesis during

theday.

Carbon dioxide entersthe plants through thestomata.

Oxygen that is producedis released into thesurroundings through thestomata too.

carbon

dioxide

oxygen

During photosynthesis



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At night, only

respiration takes

place.

Oxygen is taken in

and carbon dioxide is

given out through the

stomata.

carbon

dioxide

oxygen

All the time



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Systems - Air & the Human Respiratory System

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