Circulatory system
1/ Blood flow (Heart and circulatory
system)
2/ Blood vessels
3/ Vasoconstriction and vasodilation
Circulatory system
1/ Blood flow (Heart and circulatory
system)
Pulmonary
artery2
Vena cava
1
Aorta
3
Pulmonary
4
vein
Right atrium1
Right ventricle2
3 atrium
Left
4Left ventricle
Semi-lunar valves
4 3
1
Right Atrio-Ventricular
valve
AV valve
2
Left AtrioVentricular valve
AV valve
Carotid artery
Pulmonary vein
Jugular vein
Pulmonary artery
Aorta
Vena cava
Coronary artery
Hepatic
vein
Renal vein
Portal
vein
Hepatic artery
Renal artery
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What is the function of arteries?
Arteries take the blood Away from the heart,
What is the function of veins?
Veins have Valves
What happens as the blood moves away from the heart?
A decrease in blood pressure
Why do we need a heart made of two pumps?
One side restores blood pressure after the blood has
passed in the tiny capillaries of the organ tissues. The other
sides restores blood pressure after the blood has passed in
the tiny capillaries of the lungs.
What does oxygenated blood means?
Blood which contains a higher concentration of oxygen
than surrounding tissues.
What does deoxygenated blood means?
Blood which contains a low concentration of oxygen.
https://www.youtube.com/watch?v=ABTvNR5
9K5Q
Circulatory system
1/ Blood flow (Heart and circulatory
system)
2/ Blood vessels
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2. What does the outer layer of
connective tissue in arteries and
veins contain?
Elastic fibres
3. What is the importance of the
elastic fibres in arteries?
They enable the walls of the artery
to pulsate (stretch and recoil) to
accommodate surges in blood.
4. How does the muscular wall of
veins compare with that of
arteries?
It is thinner
5. What is the function of the
valves found in veins?
Prevent back flow of blood
6. What is the function of
capillaries?
Allow exchange of substances
between the blood and living
tissues.
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Veins carry the blood towards
the heart.
Veins have an outer layer of
connective tissue containing
elastic fibres.
They have a much thinner
muscular wall than arteries.
Blood flows along veins at lower
pressure than arteries.
The lumen of a vein is wider
than that of an artery.
Valves are present in veins to
prevent the back flow of blood.
Capillaries merge together to
form venules which again
merge to form veins which carry
the blood back to the heart.
Capillaries form a dense
network, they allow exchange
of substances with tissues.
They are only one cell thick so
they allow quick and efficient
exchange of materials.
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Arteries carry blood away from
the heart
Arteries have an outer layer of
connective tissue containing
elastic fibres and a middle layer
containing smooth muscle with
more elastic fibres.
The elastic walls of the arteries
stretch and recoil to
accommodate the surge of blood
after each contraction of the
heart.
The smooth muscle in the walls of
arterioles (small arteries) can
contract or relax causing
vasoconstriction or vasodilation to
control blood flow.
During strenuous exercise
arterioles leading to working
muscles vasodilate increasing
blood flow.
At the same time arterioles
leading to abdominal organs
vasocontract reducing blood flow.
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Function of veins?
Veins carry the blood towards
the heart.
• Structure
Veins have
an outer layer of
of veins?
connective tissue containing
elastic fibres.
How ishave
a vein’s
muscular
wall
• They
a much
thinner
compared wall
to arteries?
muscular
than arteries.
is blood
in veins
• How
Blood
flowspressure
along veins
at lower
compared
arteries?
pressure to
than
arteries.
• How
The islumen
of a of
vein
is wider
the lumen
veins
than thattoofarteries?
an artery.
compared
structure
feature of
• What
Valves
are present
in veins
veinsisto
missing
in arteries?
What
its blood.
function?
prevent
the back
flowis of
• What
Capillaries
merge together to
are venules?
form venules which again
merge to form veins which carry
the blood back to the heart.
• Function
Capillaries
form a dense
of capillaries?
network, they allow exchange
of substances with tissues.
capillaries
andthick
how so
• Structure
They areofonly
one cell
Itthey
helpsallow
its function?
quick and efficient
exchange of materials.
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Arteries
blood away from
Arteries carry
function?
the heart
Arteriesstructure?
have an outer layer of
Arteries
connective tissue containing
elastic fibres and a middle layer
containing smooth muscle with
more elastic fibres.
The
elasticofwalls
offibres
the arteries
Function
elastic
?
stretch and recoil to
accommodate the surge of blood
after each contraction of the
heart.
What is the effect of contraction or
The
smooth
the walls
of
relaxation
of muscle
smooth in
muscles
in the
arterioles (small arteries) can
walls of the
arterioles?
contract
or relax
causing
vasoconstriction or vasodilation to
control blood flow.
How dostrenuous
arterioles react
to
During
exercise
arterioles
leading to working
strenuous exercise?
muscles vasodilate increasing
blood flow.
At the same time arterioles
leading to abdominal organs
vasocontract reducing blood flow.
Circulatory system
1/ Blood flow (Heart and circulatory
system)
2/ Blood vessels
3/ Vasoconstriction and vasodilation
• The smooth muscle in the walls of arterioles
(small arteries) can contract or relax causing
vasoconstriction or vasodilation to control
blood flow.
• This process allows changing demands of the
body’s tissues to be met.
• Give 2 examples of circumstances during
which vasoconstriction and vasodilation take
place and describe the pattern of dilation and
contractions.
• During exercise
• Regulate body temperature
• During exercise
– During strenuous exercise arterioles leading to working
muscles vasodilate increasing blood flow.
– At the same time arterioles leading to abdominal organs
vasocontract reducing blood flow.
• To regulate body temperature
– When we are too hot, blood vessels supplying blood to the
skin can swell or dilate (vasodilation). This allows more
warm blood to flow near the surface of the skin, where the
heat can be lost to the air.
– When we are too cold the blood vessels supplying warm
blood to the skin become narrow or constrict
(vasoconstriction). This reduces the flow of warm blood
near the surface of the skin, and reduces heat loss.
– A very common mistake in exams is to write that the blood
vessels move up and down in the skin. The blood vessels
do not move during vasodilation and vasoconstriction.