The Circulatory System
 To
carry digested food from the small
intestine to all areas in the body which need it.
 To
carry oxygen from the lungs to the rest of
the body.
 To
aid in the disposal of all wastes from the
body.
 To
 To
distribute heat.
fight diseases by using white blood cells to
fight off infection.
 The
blood is made up of different types of cells
and a liquid medium for which they are
transported.
 The cells in the blood are Red Blood Cell
(Corpuscles), White Blood Cells and Platelets.
 Plasma is the liquid medium of blood.
 Red Blood Corpuscles are technically not cells
at all, as they do not contain a nucleus.
 Their red colour is from a substance known as
haemoglobin.
 Haemoglobin binds with oxygen so it is the red
blood corpuscles that carry oxygen in the body.
White Blood Cells are largest and not as plentiful
in the blood as corpuscles.
 These cells are used to fight infection.
 Foreign bodies are either devoured by the cells or the
cells produces antibodies, which in turn attack the
infection.
 Platelets are small fragments of cells, and are
responsible for blood clotting.
 A Haemophiliac (someone who cannot clot)
doesn’t have any platelets.
 Plasma is the medium in which all the cells are
maintained.
 It contain water, proteins (fibrinogen), food, wastes
(e.g. CO2), Antibodies and Hormones.

 The
heart is a four-chambered hollow muscle,
used to pump blood all over our bodies.
 It is divided into four compartments, the left
and right ventricles and the left and right atria
(atrium in singular).
 The right side of the heart pumps blood low in
oxygen (de – oxygenated) to the lungs.
 The left side of the heart pumps blood rich in O2
(oxygenated blood) all over the body.
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Blood enters the heart through the superior and inferior
Vena Cava and into the right atrium.
The tricuspid valve opens and the blood is moved into the
right ventricle.
The walls of the right ventricle contract and the blood is
pumped up to the lungs (through the pulmonary artery)
where oxygen replaces CO2 in the blood.
The oxygenated blood enters the heart from the lungs
through the left atrium (via the pulmonary vein).
Again a valve opens and the blood moved into the left
ventricle.
The walls of the ventricle contract and the blood is
pumped all over the body via the Aorta.
The rate of beat is controlled by the pace maker in the
septum.
Arteries:
 Carry blood away from the heart always.
 Have thick muscular walls
 Have a pulse
 Deep under the skin
 Have no valves
Veins:
 Carry blood to the heart.
 Have thin walls
 Do not have a pulse
 Near surface of the skin
 Have valves to stop back-flow of blood.
 Capillaries are small blood vessels acting as veins and
arteries.
 The walls of capillaries are only one cell thick so
substances (Food or cells) can easily get through them
and into the blood or out.
The Hepatic portal system is a transport system
between the small intestine, the liver and the heart.
 It consists of the hepatic portal vein, the hepatic
artery and the hepatic vein.
 The hepatic artery carries oxygenated blood to the
liver for use and the collection of wastes.
 The hepatic vein carries the used blood back to the
heart.
 The Hepatic Portal Vein carries blood from the small
intestine to the liver.
 This blood is low in O2 but rich in Glucose and
other food types.
 The Glucose is converted to Glycogen in the Liver
and stored there.

 Hypertension
(or high blood pressure) is
caused by the blood vessels becoming narrow
because of the build up of fat or from stress.
 The
heart therefore needs to pump harder to get
the blood through the narrow vessels.
 This
can cause the left ventricle to grow, and can
lead to the heart not functioning properly.
 The
heart also needs a supply of blood and gets
from the coronary arteries.
 If
these arteries get blocked, a heart attack
occurs.
A
stroke is caused by a blockage or leak of blood
vessels in the brain.
 Every
year in Ireland, 10,000 people die of heart
attack or stroke.
The risks factors of heart
attack and stroke are:
 Smoking – nicotine can
also block the arteries.
 Obesity – more fat
deposits in the blood vessels
 Regular exercise can
reduce the risk of heart
disease.
 Stress increases the risk of
heart attacks.
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