Download Ch15 Animal Transport + Exchange Systems

Unit 2: Multicellular Organisms
Chapter 15: Animal Transport
and exchange systems
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Unit 2: Multicellular Organisms
Chapter 15: Animal Transport
and exchange systems
Lesson 1: Mammalian
circulatory system: HEART
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Learning Intentions:
Animal Transport
By the end of this chapter you should:
• Be able to demonstrate the pathway of oxygenated
and deoxygenated blood through heart, lungs and
body.
• Describe the heart structure to include right and left
atria and ventricles and location and function of
valves (you DO NOT NEED valve names). Blood
vessels to include: aorta, vena cava, pulmonary
arteries and veins.
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Introduction
• A large multicellular organism has a small surface area in
relation to its volume. (See Torrance. ch14 – pg111).
• Therefore it needs additional absorbing areas to take in
oxygen and food.
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The need for additional absorbing
areas in humans
• Humans have for
example
– Alveoli in the lungs
– Villi in the intestine
These greatly increase
the surface area for
the absorption of
oxygen and digested
food respectively
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The need for a circulatory system
• Once the essential
substances have entered
the animal’s body, they
must be carried to all of
it’s living cells at a faster
rate than is possible by
diffusion.
• In mammals, this rapid
transport of essential
materials is achieved by
an animal’s circulatory
system.
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Mammalian circulatory system
• The circulatory system
consists of the
– Heart (a muscular pump)
– Blood vessels (a system of
tubes)
• These carry blood to all
parts of the body.
• Nutrients, oxygen, carbon
dioxide and hormones are
transported in the body.
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The Heart
The heart is a muscular pump located in the centre
of our chest. Its job is to pump blood all around the
body.
Group Task – Study this
diagram of a section through a
human heart.
Try and work out –
a) How many chambers (large
spaces) there are in the
heart?
b) Why one side is coloured
blue and one side coloured
red?
c) Why one side has a thicker
wall than the other side?
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The Heart - Chambers
• The heart is divided into two
separate sides.
• Each side has 2 hollow chambers an atrium and a ventricle.
• The upper chambers are the right
and left atria these collect blood.
• The lower chambers are the right
and left ventricles, these pump
The diagram shows the 4 chambers
blood.
viewed from the front of a person.
• The wall of the heart is made of The right hand side of a person is
therefore on the left of the diagram
cardiac muscle.
and vice versa.
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The function of veins and arteries.
We will look at their structure later!
Veins carry blood into the heart while arteries carry
blood away from the heart.
The veins carry blood into the atria while the arteries
carry blood away from the ventricles.
vein
artery
Pulmonary
Artery
Pulmonary
vein
artery
Aorta
vein
Vena cava
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Blood flow
• This diagram shows
the path taken by
blood as it flows
through the heart and
its associated vessels.
• Let’s look at it in more
detail.
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Blood flow and associated vessels
• Our blood flows through three different types
of blood vessels is shown below.
VEIN
HEART
ARTERY
CAPILLARIES
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Flow of blood: Summary
• The flow of blood
from the LV back to
the LV... As follows.
Pulmonary
Artery
Pulmonary
vein
Aorta
Vena cava
• LV> aorta> body>
vena cava> RA> RV>
pulmonary artery>
lungs> pulmonary
vein> LA> LV.
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Blood flow – In more detail
• Blood passes through the heart twice (each time it
passes around the body also called double circulation).
• The blood firstly is pumped to the lungs where it picks
up oxygen, becoming oxygenated.
• The blood is then pumped around the body where
respiring cells remove the oxygen. This deoxygenates
the blood.
• The blood vessels that carry deoxygenated blood to
the lungs are pulmonary arteries, while pulmonary veins
return oxygenated blood to the heart.
• The artery that carries oxygenated blood away from
the heart and around the body is the aorta. The vena
cava is the vein that returns deoxygenated blood to
the heart from the body.
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Rob the Red Blood Cells
Journey!
Rob is a new red blood cell and needs
direction about where he’s going and what
will happen to him on his journey around
the body.
?
Can you help advise him?
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Review Questions
•
•
•
•
Where did Rob pick up Oxygen?
Where did Rob take it to?
Why did Rob change colour?
What things would be floating around Rob in
the blood?
• What other cells are there in the blood with
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Thickness of ventricle walls
The muscle wall of the left
ventricle is THICKER than
the right ventricle. This is
because the left ventricle
has to pump blood right
round the body, whereas
the right ventricle only has
to pump blood to the lungs.
(which are right next to the
heart).
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The Heart - Valves
The heart has four valves in it. The job of the valves is
to keep blood flowing in one direction through the
heart. The valves stop the blood flowing backwards
within the heart.
Valve 4
Valve 3
Valve 2
Valve 1
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The Heart – Valves 1 and 2
• Valves 1 and 2 are situated between the atria and
the ventricles.
• When they open, blood passes from the atria into
the ventricles.
• When the ventricles contract, the blood, under
pressure closes valves 1 and 2. This prevents blood
flowing back into the atria.
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The Heart – Valves 3 and 4
• Valves 3 and 4 are situated between the ventricles
and the two arteries that leave the heart.
• Once blood has been pumped through valves 3 and 4
they close, preventing backflow of blood from
arteries into ventricles.
• Blood is therefore only able to travel in one
direction through the heart.
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Our heart beat is caused by the
valve opening and closing
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Heart valve disease
• If one or more valves
are diseased or damaged, it can
affect how blood flows through the
heart in two ways:
• If your valve does not open fully, it
will obstruct the flow of blood.
• If the valve does not close properly,
it will allow blood to leak backwards.
• People with heart valve disease may
be advised to have surgery on your
valve, which can greatly improve the
symptoms and quality of life.
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Heart valve surgery
There are two options for valve surgery:
valve repair and valve replacement.
• Valve repair is often used for mitral
valves that become floppy and leak but
are not seriously damaged.
• Valve replacement is when the
diseased valve is replaced with a new
valve. The most common types of
replacement valves are mechanical
(artificial) valves or tissue (animal)
valves.
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Consolidation exercise: The Heart
Individual task - collect the diagram which represents a section
through a human heart and stick it into the middle of a page in your
jotter.
Now see if you can complete and label
the diagram by 1) naming the four chambers.
2) drawing and shading in the
muscular walls of each ventricle.
3) indicating the positions of the four
valves.
4) naming the four blood vessels
associated with the heart.
5) drawing arrows to show the flow of
blood through the heart.
6) colouring the “correct” side of the
heart blue and the other side red.
7) indicating what the red and blue
colours
represent.
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5 Biology
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The Heart: Watch this
Watch the following video clip about the
human heart.
Heart : Twig
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Unit 2: Multicellular Organisms
Chapter 15: Animal Transport
and exchange systems
Lesson 2: Mammalian
circulatory system: BLOOD
VESSELS
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Learning Intentions: The vessels
associated with the heart
By the end of this chapter you should:
• Be able to compare the structure and function of arteries,
veins and capillaries.
• Specifically that
•
•
•
Arteries have thick, muscular walls, a narrow central
channel and carry blood under high pressure away from the
heart.
Veins carry blood under low pressure; have thinner walls and
a wide channel. Veins contain valves to prevent backflow of
blood and carry blood towards the heart.
Capillaries form networks at organs and tissues, are thin
walled and have a large surface area, allowing exchange of
materials.
• Describe coronary arteries and their function.
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There are three types of blood
vessels
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Task: Comparing Arteries and Veins
Artery
Vein
Group Task –
Study these diagrams of an
artery and a vein.
Stick copies into your notes.
1) Describe three differences
in the structure of arteries
and veins.
2) Decide in which blood vessel
the pressure will be
highest. Give a reason for
your choice.
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ANSWER:
Vessels
ComparingBlood
Arteries
and Veins
Arteries have thick, muscular walls and a narrow central
channel.
Veins have thinner walls and a wide channel. They also
contain valves to prevent the backflow of blood.
Arteries carry blood at high pressure AWAY from the
heart. Veins carry blood under low pressure back to the
heart.
Artery
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Vein
Individual Task – Study your wrists.
1) Are the blood vessels that you can
see near the surface, arteries or
veins?
2) Can you find your pulse in your
wrist? What do you think your pulse
actually is?
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What is a pulse?
Each time the heart beats,
blood is forced along the
arteries at high pressure and
this pressure wave can be felt
as a pulse beat.
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Capillaries fun facts
• There are an estimated 10 billion capillaries, measuring
approximately 25,000 miles, in the average human body.
• Each capillary has a length of about 1.1 millimeter.
• Most capillaries are little more than a single cell layer
thick.
• Capillaries are the smallest and most numerous vessels in
the body through which blood flows.
• The thin capillary wall helps to increase the exchange of
materials between cells in the tissue and the blood.
• While a person is resting, approximately 5% of the blood
circulating is in the capillaries,
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Capillary networks
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Capillaries
• An artery divides into smaller vessels and finally into a
dense network of tiny, thin walled capillaries.
• Capillaries are the most numerous type of blood vessel
in the body. They present a large surface area and are
in close contact with all living cells in tissues and organs.
This diagram shows the network of
capillaries spreading through the skin in a
fingertip. The larger blood vessels are
small arteries which carry the blood to
the capillaries.
Individual Task – Press on the tip of your
fingernail and watch what happens. Can you
explain the change in colour that occurs.
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Capillaries cont
• Capillaries are often
referred to as exchange
vessels since all
exchanges of materials
between blood and living
tissue takes place through
their thin walls (only one
cell thick).
• Capillaries unite to form
larger vessels that
converge to form veins.
• The diagram shows a
simplified version of the
human circulatory system.
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TASK COPY: Capillaries
Blood flows from arteries into capillaries and then back to veins.
As the blood flows through capillaries substances are exchanged
with the nearby body cells
This diagram shows a capillary
network in the inner lining of a
cheek.
Notice how all the cheek lining
cells are very close to a blood
capillary.
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Group Task – Decide whether the
following substances will be leaving
or entering the blood at this
capillary network.
1) Oxygen
2) Carbon dioxide
3) Glucose
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Task: Stick your diagram + complete
the task below.
Individual Task – Stick the diagram of a capillary network into
your notes. Colour the blood vessels red and the cytoplasm of the
body cells yellow.
Individual Task - below your
diagram draw one enlarged body
cell with a capillary beside it.
Individual Task – now draw arrows
to represent the movement
direction (diffusion) of
1) oxygen
2) carbon dioxide
3) glucose
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Blood Vessels: Summary: Watch this
Watch the following video clip which contains information
about blood vessels and the blood that flows around in
them.
Blood : Twig
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Coronary Artery
This diagram shows the outside of
the heart. Small arteries can be
seen branching off the aorta. These
are called coronary arteries and
they are very important as they
supply the muscles in the wall of the
heart with oxygen.
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Coronary Heart
Attack
• The coronary arteries can
become narrower as we get
older.
• A fatty diet, smoking and lack of
exercise all contribute to this.
• Eventually, a clot can block the
artery leading to a heart attack.
Muscle cells in the heart wall
become starved of oxygen and
die. The heart may stop
contracting and unless the heart
is quickly restarted the
individual will die.
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Unit 2: Multicellular
Organisms
Chapter 15: Animal Transport
and exchange systems
Lesson 3: Mammalian
circulatory system: BLOOD
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Learning Intentions: Blood
By the end of this chapter you should:
• Be able to describe that mammals, nutrients, oxygen
and carbon dioxide are transported in the blood.
• Red blood cells are specialised by being biconcave in
shape, having no nucleus and containing
haemoglobin. This allows them to transport oxygen
efficiently in the form of oxyhaemoglobin.
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Remember blood is made of
different cells
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Blood
• Blood is a liquid tissue consisting of:
–
–
–
–
plasma
red blood cells
white blood cells
platelets
• One of the functions of blood is to transport materials
around the body. White blood cells and platelets are part
of the body's immune system, but plasma and red
blood cells are involved in transport.
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Task: Can you name three nutrients that
are carried in the blood?
Group Task – Look at this
diagram which represents the
parts of blood.
Decide which part carries
a) oxygen
b) carbon dioxide
c) nutrients.
How many did you get correct?
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The Blood
Nutrients such as glucose and amino acids dissolve in the
fluid part of the blood – the plasma.
Carbon dioxide gas is also carried around the body in
blood plasma.
Oxygen is transported around the body in red blood
cells.
Group Task –
can you find
out what white
blood cells and
platelets do?
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Plasma
Plasma is a straw-coloured liquid.
It transports dissolved substances
around the body, including:
– Hormones, (Remember hormones are chemical
substances that help to regulate processes in the
body) such as insulin which regulates the level of glucose in
the blood. Oestrogen and progesterone are two hormones
involved in the female menstrual cycle.
– Nutrients, such as water, glucose, amino acids, minerals
and vitamins
– Waste substances, such as carbon dioxide and urea
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Microscopy - Seeing the
composition of Blood
This diagram shows a drop of blood as viewed under
a microscope. The nuclei of the white blood cells have
been stained purple to make them visible.
Notice how few white cells there are compared to
red cells.
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Why is blood is red?
This diagram represents an image of blood magnified
thousands of times using an electron microscope.
The bright red colour of the red blood cells comes
from the presence of a pigment called haemoglobin.
Haem = Containing iron
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Red blood cells have no nucleus
• The absence of a nucleus is
an adaptation of the red
blood cell for its role. It
allows the red blood cell to
contain
more haemoglobin and,
therefore, carry more oxygen
molecules. It also allows the
cell to have its distinctive biconcave shape which aids
diffusion
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Red Blood Cells
• FUN FACT: The average
healthy adult has 35
trillion red blood cells in
their body.
• Red blood cells have a
biconcave shape which
allows them to absorb
lots of oxygen as blood
passes through the
lungs.
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Red blood cells are very small
so they can easily pass through
narrow blood vessels.
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Haemoglobin & Oxyhaemoglobin
• As blood passes through
the lung capillaries,
haemoglobin (a dark red
colour) combines with
oxygen to form
oxyhaemoglobin (bright
read colour).
• When blood reaches the
capillaries beside respiring
cells. Oxyhaemoglobin
quickly releases the
oxygen which then
diffuses into cells.
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Consolidation exercise:
The Blood
Individual Task – Stick this diagram into your notes.
Then underneath your diagram.
1. List all the substances that are carried dissolved in
the plasma.
2. Describe three ways that red blood cells are designed
to carry oxygen around the body.
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TYK Torrance pg’s 123/4 Qu’s 1-3
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TYK – How did you do?
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TYK – How did you do?
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National 5 Biology
Unit 2: Multicellular
Organisms
Chapter 15: Animal Transport
and exchange systems
Lesson 4: Organs of
gaseous exchange
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Learning Intentions:
Structure of the lungs
By the end of this chapter you should:
• Be able to describe the structure of the lungs
•This should include...
• The trachea and its rings of cartilage which
keep main airways open.
• Comparisons can be made between cartilage
in airways and lignin in xylem.
• The cilia and mucus. Specifically that mucus
traps dirt and microorganisms and cilia moves
this up and away from the lungs.
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The Lungs
The lungs are a mammals gaseous exchange (where
gases enter and leave the bloodstream).
Can you name the gas that enters the
blood and the gas that leaves the blood
in the lungs?
windpipe
bronchus
bronchioles
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Inhaled air enters the body
through the mouth or nose.
It then travels down
through a system of tubes
decreasing in diameter the windpipe (trachea)
which divides into bronchi
(singular bronchus) which
enter each lung.
Each bronchus then
branches into lots of
smaller tubes called
bronchioles which carry air
throughout each lung.
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Task
• Collect a diagram
of the lungs and
label the various
tubes.
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The Trachea - Windpipe
The windpipe and bronchus (larger airways) are
surrounded by rings of cartilage.
rings of
cartilage
These rings are not complete.
They are c-shaped held
together by ligament
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Is there something in common with
rings of cartilage in the trachea and
lignin in xylem vessels (plants) ??
• Rings or spirals of Lignin
reinforces cell walls, keeping
them from collapsing. This is
particularly important in the
xylem, because the column of
water in the hollow xylem cells
is under tension and without the
lignin reinforcement the cells
would collapse.
•
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The Trachea - Windpipe
Individual Task – see if you can feel the rough rings
of cartilage in your own throat.
You can also feel this “rubbery” material in your
ears and at the tip of your nose.
rings of
cartilage
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Paired Task – decide what you
think the function of this cartilage
is. Clue – ligament?
The rings of cartilage protect the
windpipe by preventing it from
collapsing if it is struck. They spring
back keeping the windpipe open and
air moving into and out of the lungs.
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The Trachea – Cilia & mucus
The trachea and bronchi are lined with tiny hairlike cilia and cells that secrete sticky mucus
Dirt particles and microorganisms
that we inhale stick to the mucus
lining the windpipe. This traps
them and prevents them entering
the lungs.
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The cilia then beat rhythmically
back and forward sweeping the
dirty mucus away from our lungs,
up to our mouth. This mucus is
then swallowed and the acid in
our stomach kills the
microorganisms.
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5 Biology
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Microscopy of the Windpipe
Section through lining layer
(epithelium) of windpipe showing cilia
and mucus-producing goblet cells
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Scanning electron
micrograph image of cilia in
the windpipe.
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The internal structure of the lung Alveoli
This diagram shows that the bronchioles in each
lung end in groups of tiny air sacs deep in the lungs
called alveoli (singular alveolus). These air sacs are
the place where oxygen and carbon dioxide are
exchanged with the bloodstream.
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Why are alveoli so numerous?
• Alveoli are so numerous that they
provide a very large surface area
for gas exchange with the blood.
• There are around 300 million
alveoli in each lung (600 million
in total).
• The total internal surface area
of the two lungs is about 90m2
• If they were flattened and
stitched together they would
cover an area equal to a tennis
court.
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National 5 Biology
Unit 2: Multicellular
Organisms
Chapter 15: Animal Transport
and exchange systems
Lesson 5: Gas Exchange
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Learning Intentions: Gas
Exchange
By the end of this chapter you should:
• Be able to describe the gas exchange in the lungs
•This should include...
• Oxygen and carbon dioxide are exchanged
through the alveolar walls. Alveoli have a large
surface area, thin walls and a good blood supply
for more efficient diffusion of gases.
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Internal structure of the lung
- Alveoli and capillary network
Alveoli are well designed for gaseous exchange.
They are surrounded by a dense network of
capillaries which give a rich blood supply. If the
capillaries from a man’s lungs were unwound and
laid end to end they would stretch for 600 miles.
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Alveoli and capillary network –
Structure related to function
• As discussed the alveolus is surrounded by a dense
network of blood capillaries.
• The lining of an alveolus is very thin and in close
proximity to the walls of the blood capillaries, which are
themselves only one cell thick.
• This combination of
– Large surface area
Presents ideal conditions for
– Short distance
gas exchange to occur
– Thin walls
between alveolar air and
– Good blood supply
blood.
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Task: Alveoli
Paired task
Study the diagram –
a) Decide which part
of the blood oxygen
enters and which
part carbon dioxide
leaves.
http://www.bbc.co.uk/bitesize/ks3/science/o
rganisms_behaviour_health/life_processes
/revision/5/ - SEE ANIMATION
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b) Suggest why the red
blood cells are
shown in different
colours in the
diagram.
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Gas Exchange - Getting oxygen
from the air into the blood,
• Blood arriving at the lungs is described as
deoxygenated because it contains a low concentration
of oxygen.
• Since air breathed into an alveolus contains a higher
concentration of oxygen, diffusion occurs.
• Oxygen first dissolves in the moisture on the inner
surface of the thin lining of the alveolus and then diffuses
into the blood and surrounding capillaries.
• The blood therefore becomes oxygenated (rich in
oxygen) before leaving the lungs and passing to all parts
of the body.
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Gas Exchange - Removing waste carbon
dioxide from the blood into the air
• Deoxygenated blood
contains a higher
concentration of carbon
dioxide than the air
entering the alveoli.
• Therefore carbon dioxide
diffuses from the blood
into the alveoli from where
it is exhaled.
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Individual consolidation task:
1) Collect the alveoli diagrams and stick them into your
jotter.
2) On the first diagram label the alveoli, blood capillaries
and the bronchiole.
3) On the second diagram do the following –
a) Draw in some red blood cells.
b) Label the capillary, alveolus wall and bronchiole.
c) Draw arrows in different colours to show the flow of
oxygen and carbon dioxide between the alveolus and
the blood.
4) Underneath your diagrams list three ways that alveoli
are designed to allow efficient diffusion of gases.
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The Lungs in Action
Individual Task
Study the animation which illustrates the flow of gases into and
out of the lungs(Multimedia Science School).
List all the parts of the body that oxygen passes through from
entering the body until it reaches the muscles.
Now list all the parts of the body that carbon dioxide passes
through from the muscles until it is breathed out.
Can you now explain why there is less oxygen and more carbon
dioxide in the air we breathe out.
Finally, describe what happens to our breathing when we start
to run having been resting.
Can you now explain why this change in our breathing happens?
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The Lungs – Watch this
Watch the following video clips about the lungs.
Lungs : Twig
FactPack: Lungs : Twig
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National 5 Biology
Unit 2: Multicellular
Organisms
Chapter 15: Animal Transport
and exchange systems
Lesson 6: Food Transport
System
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Learning Intentions:
Food Transport System
By the end of this chapter you should:
• Be able to demonstrate that
• Food is moved through the digestive system by
peristalsis.
• Understand the structure of villi in the small intestine
• Specifically they have a large surface area,
thin walls and a good blood supply to aid
absorption of glucose and amino acids.
• Understand the structure of villi in relation to the
lacteals which absorb fatty acids and glycerol (the
products of fat digestion).
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Food transport system
• The alimentary canal is our
body’s digestive system.
• As insoluble molecules of food
pass along this muscular tube
they are broken down to a
soluble state by digestive
enzymes.
• The salivary glands, liver and
pancreas, which are connected
by ducts to the alimentary canal
(gut) are described as associated
organs.
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Revision: Digestive System Structure
The digestive system is essentially a continuous
tube which runs from the mouth to the anus. The
human gut is over 5 meters long!
A
B
D
C
E
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Individual Task – Study
this diagram of the
digestive system and
see how many parts (AE) that you can identify.
A = Oesophagus (gullet)
B = Stomach
C = Small Intestine
D = Large Intestine
E = Rectum
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Oesophagus and Peristalsis
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• The oesophagus
(gullet) is a muscular
tube that connects
the mouth to
stomach.
• Once food had been
swallowed, it is
moved down the
oesophagus by
muscular action
called
Mrs Smith - National
5 Biology peristalsis.
84
Mechanism of Peristalsis
Contraction
behind food
Relaxation in
front of food
• Part of the gut wall is composed
of circular muscles.
• When this contracts behind a
portion of food, the central hole
of the tube becomes narrower
and the food is pushed along.
• At the same time the circular
muscle in front of the food
becomes relaxed allowing the
central hole to enlarge and let
the food slip along easily
http://www.westga.edu/~lkral/peri
stalsis/index.html
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Functions of Peristalsis
• Peristalsis also squeezes
semi-solid food through the
stomach and along the
intestines.
1. PERISTALSIS OF THE
STOMACH
• This movement helps to mix
the food with digestive juices.
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Functions of Peristalsis
• Peristalsis also squeezes
semi-solid food through the
stomach and along the
intestines.
2. PERISTALSIS OF THE
INTESTINE
• This movement helps Following
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absorption of the end products
of digestion in the small
intestine peristalsis keeps
unwanted wastes on the move
through the large intestine on87
Mrs Smith - National 5 Biology
their way to be eliminated.
End products of digestion
• Imagine the small intestine
of a person that has just
eaten an egg sandwich.
• As a result of complete
digestion
– the starch in the bread has
been broken down into
glucose.
– The protein in the egg to
amino acids
– The fat in the butter to the
products of fat digestion
(Fatty acids and glyserol)
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What happens to the end
products of digestion?
• So after complete digestion
– Carbohydrates are broken down into glucose.
– Proteins are broken down int amino acids
– Fats are broken down into fatty acid and
glycerol
• All of these different substances must now
be absorbed and transported around the
body
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Absorption in the small intestine
• Man’s small intestine is around 7 metres in length
and 2·5cms in diameter.
• The main function of the small intestine is to
absorb the end products of digestion through its
wall and then pass them into the circulatory
system.
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Absorption in the small intestine
Structure related to function
• The small intestine is very
efficient at its job because of its
structure.
• In biology structure is always
related to function!
• It is long and its internal
structure is folded.
• The inner lining of the small
intestine is not smooth.
• Instead, it has thousands
microscopic, finger-like,
projections called villi (singular
villus) protruding from it.
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Task: Villi
Paired task
Study this diagram which
shows villi on the inner lining
of the small intestine.
a) Decide what their
function might be.
Clue – they contain a rich
blood supply.
b) Suggest how their shape
helps them to function?
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The role of Villi
•
•
Villi increase the surface area of the small intestine for
the absorption of digested food into the bloodstream.
In addition to providing a large surface area villi are
ideally suited to the jobs of absorption and transport of
digested food because each villus has a special structure
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Villus Structure
This diagram represents a section
through one villus.
There are three structural
features which aid absorption.
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1) The surface walls are thin (one
cell thick) to allow digested
food to easily diffuse (pass)
through rapidly.
2) It contains a good blood supply.
A dense network of blood
capillaries absorb glucose and
amino acids.
3) Tubes in the centre called
lacteals absorb and transport
the products of fat digestion.
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TASK: Villus Structure
Individual Task
Collect the villus diagram and stick it into the centre of your
jotter.
Draw an arrow onto your
diagram to represent the
absorption of glucose and
glucose and
amino acids.
amino acids
products of
fat digestion
Now draw another arrow on
the diagram to represent
the absorption of the
products of fat digestion.
Note – you will have to
distinguish these arrows in
some way.
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The Digestive System
Watch the following video clips about digestion and the
small intestine.
Introduction to Digestion : Twig
Small Intestine : Twig
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TYK Torrance pg’s 128 Qu’s 1-4
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TYK – How did you do?
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