Download Get your students involved in the Olympic

Series 8
15
Blood is vital for life. It carries oxygen,
nutrients and hormones to the body via a
network known as the circulatory system.
This system also helps heal wounds, fight
infections and take away wastes. Powered
by a remarkable pump known as the heart,
some people fail to keep their circulatory
system in good condition.
Brain
common carotid artery
jugular vein
subclavian artery
subclavian vein
axillary vein
superior vena cava
In ancient times people tried to
figure out the heart and the
circulatory system. The ancient
Egyptians thought the heart
pumped blood to convey fluids and
even order to the body, but did not
realise that the blood circulated.
Ancient Greek physician Galen
(about AD129-210) believed the
system was responsible for
pumping pneuma, a vital spirit in
the air, around the body. He also
believed the liver manufactured the
blood and carried nutrients around
the body. In 1628 English physician
William Harvey published his book
William Harvey
De Motu Cordis et Sanguinis in
Animalibus ( An Anatomical Exercise Concerning The
Motion Of The Heart And Blood In Animals ). In this book
he explained how simple experiments showed that blood
circulated throughout the body pumped by the heart.
Italian doctor Marcello Malpighi (1628-1694) would
complete the picture by discovering the role of the
capillaries. He was also the first person to see red
blood cells and discover that they gave blood its colour.
cephalic vein
pulmonary artery
pulmonary vein
azygos vein
heart
brachial vein
inferior vena cava
descending aorta
mesenteric artery
testicular/
ovarian artery
Heartbeat sequence
kidney
basilic vein
renal artery
renal vein
radial artery
common iliac
artery
common iliac
vein
palmer
arterial
arch
Full right
atrium
palmer
venous
arch
Inferior
vena cava
digital
veins of
the hand
femoral artery
digital arteries
of the hand
femoral vein
great saphenous vein
arterial network
of the knee
protective
outer layer
venous network
of the knee
digital arteries of the foot
tricuspid
valve
mitral
valve
Right
ventricle
Left
ventricle
descending aorta
Myocardium
(heart muscle)
muscle
layer
Full left
atrium
inner
lining
2
Full right
ventricle
Full left
ventricle
In the diastole phase the atria and ventricles relax,
allowing blood to flow from the atria to the ventricles.
Deoxygenated
blood flows
to the lungs
3
Open aortic
valve
Contracted
ventricle
In the systole phase the ventricles contract,
forcing blood into the pulmonary artery and aorta.
PLATELETS
A doctor takes a
patient’s pulse
There are three kinds of blood vessels:
1. Arteries Carry blood from the heart to the rest of the body.
They have a thick layer of muscle to cope with the high pressure.
2. Veins Carry blood from the body back to the heart. Thinner than arteries,
veins have valves inside to stop the blood flowing away from the heart.
3. Capillaries Carry blood between arteries and veins, forming a
platelets
web through body tissue to allow oxygen and nutrients to filter out to
all parts of the body. The capillaries are the most numerous vessels
red
and the thinnest. The walls are just one cell thick, which makes them
blood
leaky enough to allow the nutrients and oxygen to get through.
cells
s Platelet concentrates
shown under a microscope
outer
layer
Did you know?
direction
of blood
flow
3
red
blood
cells
n It was once believed that the heart was
the centre of all emotions. We still refer
to the heart when talking about emotions.
n If you put all of the blood vessels in an
adult human body end to end they would
wrap around the Earth four times.
n Blood cells are created in the bone
marrow. Each cell has a lifespan of about
120 days. Red blood cells contain no
nucleus and therefore
have no DNA.
Get your students involved in the Olympic experience with The Daily Telegraph’s new resource kit
If an injury occurs platelets, the smallest
blood cells, help to stop bleeding by plugging
the broken blood vessel wall and releasing
chemicals that promote clotting.
RED BLOOD CELLS
s Red blood cells
These pigmented cells also called erythrocytes
contain haemoglobin, which contains iron that
attracts oxygen. These give blood its red colour.
The cells have a large surface area to absorb
oxygen from the lungs but are flexible enough
to squeeze through small blood vessels
(some measuring as little as 0.005 mm
or 5 micrometers).
WHITE BLOOD CELLS
There are five main types of white blood cell,
neutrophils, eosinophils, lymphocytes,
basophils and monocytes. They all have
particular roles to play. Some, known as
phagocytes, destroy foreign organisms.
white
blood
cells
valve
flap
cell
nucleus
Contracted
left atrium
Oxygenated
blood from
left lung
2
Oxygenated
blood flows to
the uPper and
lower body
Blood vessels
inner
lining
capillary
wall
Aorta
Contracted
right atrium
Flowing through the network of veins, arteries and
capillaries that make up most of the circulatory
system is the blood. Blood is composed of:
1
n When blood carries plenty of
oxygen it becomes bright red.
The blue colour of veins is due
to the fact that they
are carrying little or
no oxygen.
digital veins of the foot
aortic
valve
The pumping of the heart, or more specifically the opening and closing of
heart valves, creates waves of movement in the arteries that can be felt
as a throbbing. This is known as a pulse. The best places to feel this are
an artery in the wrist and the carotid artery in the neck. The pulse is
useful for checking to see if a person has a normal blood circulation.
Pulse rates vary according to how active the body is, but emotional
excitement can also make the pulse rate race. Pulse rates also vary from
person to person and even according to age. A baby’s pulse rate per minute at rest can be between 110 and 140, an adult’s between 50 and 85.
elastic
layer
n About 98 per cent of the entire
length of the circulatory system is
made up of capillaries.
dorsal vein of the foot
Pulmonary
veins
Blood
muscle
layer
Did you know?
posterior tibial artery
dorsal artery of the foot
Right
atrium
Pulse
peroneal artery
posterior tibial vein
LEft
atrium
inferior
vena cava
Oxygen-poor blood enters the heart from
the superior and inferior vena cava.
anterior tibial artery
Sometimes, when blood flow is restricted to an area
of the body, a person can experience numbness and
then a prickling or tingling sensation called paraesthesia,
also known as “pins and needles”. This happens because
the nerves, which provide information for the sense of
touch to the brain, are deprived of blood, resulting in
that area of the body losing this sense. When the blood
returns the nerves begin sending messages again, giving
that tingling feeling. Cutting off the circulation for long
periods can cause damage. Persistent feelings of
tingling may indicate nerve damage.
and pumps it to the lungs. Oxygen-rich
blood coming from the lungs then enters
the left side of the heart where it is
pumped around the body. The heart is
made up of long thin fibres of muscle
that beat in time with each other according
to a natural pacemaker in the right atrium.
Superior
vena cava
1
anterior tibial vein
Pins and needles
Pulmonary
artery
ulnar artery
testicular/
ovarian vein
small saphenous vein
A doctor takes a patient’s blood pressure
Pulmonary
artery
pulmonary
valve
Although it is only the size of a fist, the
heart pumps blood around a system of
blood vessels that measures about
50,000km. It has four chambers, a left and
a right atrium and a left and right ventricle.
The chambers on the right side take in
blood from the body that is low in oxygen
brachial artery
Blood pressure
Blood pressure is a measure of how much the blood pushes
on the walls of vessels in the circulatory system. It is usually
measured using a stethoscope and a sphygmomanometer
and is recorded using a two-number system, for instance
120/80. The first number is the systolic blood pressure,
the pressure in the arteries as the heart pumps it out. The
second number is the diastolic, the pressure in the arteries
when the heart relaxes after pumping. Blood pressure varies
according to what the body is doing. If blood pressure is too
high or too low it can cause problems. High blood pressure,
or hypertension, has many causes but a common one is
blockage of the arteries. It can cause serious problems such
as heart attack. Low blood pressure, or hypotension, is often
caused by a loss of blood or other fluids or vasodilation,
widening of the blood vessels. It can cause dizzy spells,
fainting, shortness of breath and even seizures.
Aortic
arch
superior
vena cava
The heart
hepatic vein
hepatic artery
Inside the heart
axillary artery
Aortic arch
Discovering circulation
Circulatory
system
THE
PLASMA
Blood is about 55 per cent plasma. A yellowish
liquid, plasma consists mostly of water but
10 per cent is nutrients including glucose, salts,
hormones and proteins. One of the proteins is
fibrinogen, which has a key role in blood clotting.
plasma
Find out more
Sources and further study:
DK E.explore Human Body by Richard Walker (DK)
Encyclopedia Of The Human Body by Richard Walker (DK)
Cambridge Illustrated History: Medicine edited by Roy Porter (Cambridge)
The Human Body (BBC DVD)
Encyclopaedia Britannica
Editor: TROY LENNON Designer: PAUL LEIGH
FOR DETAILS GO TO
www.news.com.au/dailytelegraph/classmate
Tuesday 11.30am on