Download The circulatory system

The Circulatory System
Heart, Blood, Blood Vessels
© PDST Home Economics
The Heart
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Pump for the blood
In the chest, between
the lungs, protected by
breastbone, ribs, spine.
Size of the owners fist.
Structure of the heart
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Hollow inside
Divided in two lengthways by septum
Has 4 chambers
Upper chambers = left and right atria (atrium)
Lower chambers = left and right ventricles
Valves separate the atria from the ventricles and prevent
backflow of blood
Structure of the Heart
Blood Flow through Heart
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Deoxygenated blood gathered from all around the
body flows into the R atrium in veins called the vena
cava.
It then flows through the tricuspid valve into the R
ventricle.
The R ventricle contracts the tricuspid closes and
the blood flows out other valves into the pulmonary
artery which takes it to the lungs to have oxygen
added and to have carbon dioxide removed.
Blood Flow through Heart
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The oxygenated blood returns to the L atrium in the
pulmonary veins.
It then goes through the bicuspid valve into the L
ventricle.
The L ventricle contracts, closes the bicuspid valve
and the blood goes out through valves into the aorta
the largest artery in the body.
The aorta splits into many branches and takes blood
to every body cell.
The cells take food and oxygen out of the blood and
put carbon dioxide and other waste into it.
Then the whole process begins again.
Flow of blood through the heart
Blood circulation in
the body
Coronary circulation
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The cells that make up the wall of the heart need a
supply of blood.
This blood is carried by a special artery called the
coronary artery a branch from the aorta.
If these blood vessels get blocked with fat a person
is suffering from coronary heart disease
Coronary artery
The blood
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4-5 litres
Plasma (yellow liquid)
Red blood cells
White blood cells
Platelets
Red blood cells
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Contain a red pigment
called haemoglobin
Oxygen sticks to the
haemoglobin and gets
carried in the
bloodstream
To make haemoglobin
the body needs Iron
White blood cells
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Fewer but bigger than
red blood cells
They attack and kill
harmful bacteria and
viruses and fight
diseases.
They make anti-bodies
that fight disease.
Platelets
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These make the blood clot
so not too much blood is
lost when we get cut.
Functions of blood
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Transport: oxygen, food, waste products, heat,
chemicals.
Prevents infection, fights disease.
Prevents blood loss by clotting
Blood Vessels
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Tubes that the blood flows through
Three types
Arteries, Capillaries, Veins
Arteries
Largest vessels
 Walls made of 3 layers
1 outer connective tissue
2 middle muscle
3 inner endothelium cells
 Mainly carry oxygenated blood (pure)
 Carry blood away from the heart
 Blood in arteries is under great pressure so their walls
need to be strong and elastic.
 The pulse is the gush of the blood through an artery near
the skin surface after each heartbeat.
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Capillaries
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Smallest vessels
Arteries divide again and again
an eventually form capillaries.
Very thin walls made of
endothelial cells
Thin walls allow substances to
get out of and into the blood
Capillaries join up to make
veins
Veins
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Walls are thinner than arteries but
lumen is bigger
Same 3 layers in walls as arteries
Blood under low pressure so valves
needed to prevent backflow
Mostly carry deoxygenated blood
(impure)
Carry blood towards the heart
Take Your Pulse