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• Blood is a tissue that transports substances
around the body
• Blood carries oxygen and glucose to the cells
of the body and transports waste and carbon
dioxide away from the cells.
• It contains red and white blood cells and
platelets floating in liquid plasma.
• Red blood cells contain a red pigment called
haemoglobin that carries oxygen. Red blood cells are
the part of blood that gives it it’s colour. They also
have a large surface area and are without a nucleus to
make more room for oxygen.
• White blood cells fight pathogens to prevent disease.
They do this by producing antibodies or carrying out
phagocytosis.
• Platelets are small fragments of cells that help the
blood to clot by forming a network with proteins in
the blood.
• Plasma is a pale yellow liquid which contains
nutrients such as glucose, waste products such
as carbon dioxide and chemicals. All the blood
cells float in the plasma.
There are three types of blood vessels in our
bodies:
1) Arteries
2) Veins
3) Capillaries
Arteries carry blood away from the heart.
The blood coming from the heart has to be
pumped at high pressure around the body so
arteries have thick, elastic walls to
withstand the high pressure of the blood.
As the blood is pumped, the walls flex and
recoil, we can feel this if we put our fingers
on our necks or wrists. It is called a pulse.
Diagram of an Artery
Veins carry blood to the heart.
The blood going to the heart is at lower
pressure than that in the arteries so veins
have thinner walls and valves to stop the
blood flowing back the wrong way.
Diagram of a Vein
Capillaries carry nutrients and oxygen to
cells and remove carbon dioxide and waste
from cells.
Capillaries have walls that are just one cell
thick to allow these substances to pass in
and out of the blood easily.
Diagram of a Capillary
Blood is pumped from the heart through the
arteries, these get smaller and smaller until
they become capillaries which carry the
nutrients and oxygen to the cells. The
capillaries then join together again to form
veins and carry waste and carbon dioxide
back to the heart.
• The heart is a pump
• It is made of a special type of
muscle called cardiac muscle
• It pumps blood around your
body
• It is the size of your fist
• It is divided in half to produce a left
and a right side
• Each side has two chambers
• The upper chambers are called the
ATRIA
• They receive blood into the heart
• The lower chambers are called the
VENTRICLES
• They pump blood out of the heart
On your diagram of the heart put
on the following labels
Right atrium
Left atrium
Right ventricle
Left ventricle
Double Circulation
• Blood passes through
the heart twice on one
journey around the body
• It goes through the
heart first to be sent to
the lungs
• It then returns to the
heart
• Second time it is
pumped around the body
• This is known as double
circulation
On your diagram of the heart put
on the following labels
From the lungs
To the lungs
From the body
To the body
Can you resuscitate this man???
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Key stage 3
Biology
37. The Circulatory System
Coronary arteries become blocked
with deposits of cholesterol
This cuts off blood supply to the
heart muscle
The cells do not have oxygen or
glucose
Therefore they cannot respire
No energy is produced
Muscles cannot contract
Heart stops beating
Heart Attacks
• The muscle cells will respire
anaerobically for a short
time.
• This produces lactic acid
and cramp
• This is what causes the pain
in a heart attack
Risk Factors
• High Cholesterol Diet
• Stress
• Smoking
• Lack of Exercise
• High Blood Pressure
One of the problems about a heart attack is that the
ventricles flutter irregularly rather than beating
properly.
In the 1970’s, Frank Pantridge, working at the Royal
Victoria Hospital in Belfast, invented a portable
defibrillator.
This gives the heart a short, sharp electric shock
which is enough to get it beating properly again.
It is small and light and can be carried in an
ambulance or kept in workplaces, ready for use
should someone have a heart attack.
defibrillator demonstration