Download Erythrocytes (red blood cells)

Blood
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Human Biology.
Clare Hargreaves-Norris
Introduction
The circulatory system is comprised of:
 Blood, this fluid transports vital
substances to all areas of the body.
 Blood is transported in vessels known as
arteries, veins and capillaries.
 The heart acts as a pump to move the
blood around the body.
Clare Hargreaves-Norris
Main Functions of Blood.
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There are three main functions of blood.
–
Transportation.
–
Defence.
–
Regulatio.
Clare Hargreaves-Norris
1. Transportation
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Erythrocytes, (red blood cells), carry oxygen to
the cells of the body.
Carbon dioxide is carried back to the lungs.
Nutrients such as glucose, vitamins and minerals
are transported around the body.
Hormones are secreted into the blood and attach
to the plasma so that they can be transported
around the body to their target organs.
All waste materials such as urea are carried in the
blood to be removed and excreted.
Clare Hargreaves-Norris
2. Defence
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There are five types of leucocytes, (white blood cells).
All leucocytes are responsible fighting infection,
(protecting the body from disease).
Some leucocytes work as phagocytes, (they engulf and
destroy microorganisms).
Some leucocytes, (lymphocytes), produce antibodies, which
give the body future resistance to re-infection.
Coagulation. Platelets start the clotting process to prevent
excessive blood loss and to stop infection from gaining
entry into the body.
Clare Hargreaves-Norris
3. Regulation

Blood regulates body heat by absorbing it
from the liver and muscles as it passes by,
and then transports it around the body.
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Composition of blood
Blood is made from
 Plasma (55%) a strawcoloured fluid
 Erythrocytes (red
blood cells)
 Leucocytes (white
blood cells)
 Platelets
(Thrombocytes)
Clare Hargreaves-Norris
Structure
Plasma
Function
90%
water.
Renews the cellular
8% plasma proteins. fluid.
Maintenance of pH
2% hormones,
of the blood at 7.4.
enzymes, nutrients,
inorganic ions
Makes the blood
(electrolytes) and
viscous.
waste.
Provision of energy
to the cells.
Produces chemical
reactions.
Protection against
infection.
Clare Hargreaves-Norris
Erythrocytes
(red blood
cells)
Structure
Function
Minute
Red
biconcave discs.
Obtain their red colour
from haemoglobin that
combines with oxygen to
form oxyhaemoglobin.
 Made in the red bone
marrow.
Take approximately 7
days to form.
They function for
approximately 4 months.
They are then destroyed
by the liver or spleen.
blood cells
carry oxygen
around the body to
the cells.
Carbon dioxide is
taken away from
the cells.
Clare Hargreaves-Norris
Leucocytes
(white blood
cells)
Structure
Function
Colourless

Contain
a
cells.
nucleus.
Larger than red
blood cells.
Less white cells
than red.
Ratio
approximately 1
to every 600 red
cells.
1.
1.
2 different types:
Granulocytes, (75%),
-Neutrophils, (54%),
phagocytosis.
- Eosinophils, (1%),
allergic reactions,
defence against worms.
-Basophils, (!%),
inflammatory response.
Agranulocytes.
-Lymphocytes, (23%),
produce antibodies to
kill foreign proteins.
-Monocytes, (2%),
Clare Hargreaves-Norris
phagocytosis.
Platelets
(Thrombocytes).
Structure
Function
Platelets
Start
are
formed in the red
bone marrow.
Tiny fragments.
Even smaller than
red blood cells.
the blood
clotting process by
producing a substance
called thrombokinase.
This sets off a chain
of reactions.
This results in the
laying of fibres, which
cover the wound.
Prevention of blood
loss.
Prevention against
invasion of infective
microbes.
Clare Hargreaves-Norris
Blood clotting
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Platelets produce a
substance called thrombokinase.
This sets off a chain of reactions
resulting in the laying of fibres
which cover the wound.
This prevents blood loss and
invasion of foreign materials.
When the blood clots it forms a
scab.
This is a natural protective seal
to the area.
Clare Hargreaves-Norris
Factors affecting the blood clotting
process
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It is important that you are aware that
certain factors can affect the blood
clotting process. The health and efficiency
of the blood supply can be affected by:
Smoking
Alcohol
Poor nutrition intake
Anti-coagulant drugs such as warfarin and
aspirin.
Clare Hargreaves-Norris