c21 respiration

8/3/2019 C21 Respiration

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RespirationRespiration


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21.1 Why do Living Things Respire?

Purpose of Respiration

All living organisms need energy to carry out activities

like movement, growth and reproduction.

This energy is obtained from the food the organismstake in.

Energy Conversion

Plants convert light energy from the sun to chemicalpotential energy stored in food substances.

Animals get this energy by feeding on plants or on

other animals that feed on plants.


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Energy Transfer through living

organisms

Plants convert light energy

to chemical energy stored

in food substances.

Some animals get energy

by feeding on plants.

Other animals such as

humans get energy by

feeding on plants as well as

animals that feed on plants.


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21.1 Why do Living Things Respire?

Where does respiration occur?The energy stored released from the food substance when thefood is are broken down in the cells, in a process known asrespiration.

Definition of RespirationThe process by which food molecules are broken down torelease energy is called respiration.

Usefulness of Respiration

Living organisms use this energy in many ways such as1. muscle movement,

2. producing new materials, such as muscles and bloodtissue,

3. maintaining a constant body temperature in animals.


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21.2 Aerobic Respiration

What are the reactants and products of aerobic respiration?

Respiration occurs in every living plant and animal cell.

glucose water

carbon

dioxide

energyoxygen


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The word aerobic means "requiring air", but the only

important component of air (as far as respiration is

concerned) is the gas oxygen.

Most living organisms, both animals and plants, need

oxygen for respiration to take place.

Since oxygen is needed, we call it aerobic respiration. It can

be summarised in the equation below:

Glucose + Oxygen Carbon dioxide +Water + Energy


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What are the reactants and products of aerobic respiration?

In respiration, glucose in food substances combines withoxygen to release energy.

Carbon dioxide and waterare produced as waste products.

Enzymes speeds up the reaction.


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Respiratory System


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Breathing refers to the movements that bring about an

exchange of gases between the body and its

surroundings.

The air that we breathe in is called inspired (orinhaled) air.

The air that we breathe out is called expired (orexhaled) air.

W

atch a video:o Breathing Movementshttp://www.youtube.com/watch?v=Mf8xTqfspp4&NR=1


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Diaphragm movement and

breathing


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1. Diaphragm pushes down.

Lungs volume increases.

2. Pressure in lungs is lower

than surrounding.

3. Air enters into lungs.


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1. Lungs volume decreases.

2. Pressure in lungs ishigher than surrounding.

3. Air exits from lungs.


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What happens in breathing?

Most animals

o take in oxygen (O2) &

o release carbon dioxide(CO2)

Where does the exchange

of gases occur?

Humans use the lungs for

the exchange of gases.

external nostril

lungs carbon dioxide

oxygen


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lungs

heart

air sac

air movement

thin film of

moisture

blood capillary

1. In the lungs, air sacsare surrounded by tiny

blood vessels called

blood capillaries.

2. Oxygen entering the

air sacs diffuses

into the blood inthe blood capillaries.

3. Carbon dioxide produced by other parts of the

body enters the bloodstream. In the lungs,

carbon dioxide diffuse from the blood into

the air sacs. Carbon dioxide is then released

when we breathe out air.

red blood cells

tissue cellsoxygen diffuses into tissue cell


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The air sac can also be called the

alveoli.

- TO other parts of the body

- Blood is oxidised (full of oxygen)

- FROM other parts of the body

- Blood is deoxidised (lacks oxygen and full of carbon dioxide )

Watch the aerobic respiration video:

Respiration 3D Medical Animation

http://www.youtube.com/watch?v=HiT621PrrO0&feature=related


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What is the difference between

respiration and breathing?Breathing Respiration1. It is a physical process

involving the exchange of

oxygen and carbon dioxide.

1. It is a chemical process

involving the reacting glucose

and oxygen to produce carbon

dioxide and water.

2. Energy is NOT released 2. Energy is released

3. It takes place outside the

cells.

3. It takes place within the cells.

4. Enzymes are NOT involved. 4. Enzymes are used in the

chemical reaction.


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21.3 How do Plants Breathe?

Like animals, plants

needs oxygen for

respiration.

The exchange of

gases takes place

mainly through

openings in the

leaves called

stomata.

oxygen diffuses

out through stoma

carbon dioxide

diffuses in through

stoma PhotosynthesisPhotosynthesis


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Two stomata on a duckweed leaf.

Stomata, which means "mouths" in Greek, do indeed resemble tiny

mouths surrounded by swollen lips. The "lips" are actually individual

cells (called guard cells) that can swell up even further to close off the

stomata.


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Did you just say that plants breathe?

It is important to realise that green plants respire at all times, like

all living organisms. However, they are unique in that they can

also make their own food by photosynthesis . As a by-product of

this process, they produce a waste substance, oxygen, which they

release from the cells of their leaves into the air.

Of course, plants may re-use some of this oxygen produced in

photosynthesis for aerobic respiration. So it is WRONG to

assume that plants do not need oxygen, or do not respire in the

same way as other living organisms.What happens in these

plants is merely a question ofbalance between the processes of

photosynthesis and respiration.


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At night, photosynthesis does not take place.

o Oxygen enters the air spaces in the leaves by

diffusion.

o The carbon dioxide produced in respiration entersthe air spaces in the leaf, then leaves the leaf

through stomata by diffusion.


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In the day, when photosynthesis occurs, the carbondioxide in the leaf is rapidly used up.

As a result, the carbon dioxide concentration in the airspaces in the leaves becomes lower than that of the

surrounding air. Thus, carbon dioxide diffuses through the stomata

into the air spaces in the leaf.


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Occurs only in

the day

Occurs both day

and night


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21.3 How do Plants Breathe

oxygen carbon dioxide

Night Day

carbon dioxideoxygen

oxygencarbon dioxide

Gaseous exchange during photosynthesis

Key:

Gaseous exchange during respiration

c21 respiration

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