Blood
Did you know that your body contains around 5 litres of blood? Your blood is technically a liquid
connective tissue – it transports many substances through your body and helps to maintain
homeostasis - the control of your internal conditions such as nutrient, water, waste and gas levels.
Your blood is made up of red blood cells,
white blood cells, platelets and liquid plasma
(which is actually yellow!)
red blood cells
white blood cells
platelets
Fo r ev ery cu bi c
m ill ili tre of bl oo d
A ro un d 4-6 m ill
4,5 0 0 -11,0 0 0
15 0,0 0 0 - 4 0 0
, 0 0 0 pl atel ets
O n an av erag e da
io n re d bl oo d ce lls
w hi te bl oo d ce lls
y yo u prod uc e:
20 0, 0 0 0 m ill io
10,0 0 0 m ill io n
w hi
plasma
4 0 0, 0 0 0 m ill
Red Blood Cells
Red blood cells are also known as erythrocytes,
and are the most common type of blood cell and
make up around 45% of your blood. They are known
as phantom cells as all that they contain is a large
amount of haemoglobin – a protein that has a great
affinity for combining with oxygen. Red blood cells
cannot reproduce themselves, and must be replaced
by new blood cells that are produced inside of red
bone marrow from stem cells at the amazing rate of
about 2 million cells every second!
Red blood cells are biconcave – they are like discs
with a curve on both sides into the middle, so that
the centre is the thinnest part. This means they can
bend and take on a bell shape to
pass through the thinnest blood
vessels. It also gives them a high
surface area to volume ratio.
Immature red blood cells begin
ngs of the arterioles. They
with a nucleus, but this is pushed
hinnest blood vessels
mon. Nearly every tissue
out of the cell when it is fully
aries running through
mature, to make it as flexible as
o arterioles on one end
it is and give it its shape. This
her. These capillaries are
does however mean that they
e of oxygen, nutrients and
carry no DNA, meaning that they
st carry blood very close
es in order to make this
cannot repair themselves when
they become damaged.
yo u have :
n re d bl oo d ce lls
te bl oo d ce lls
io n pl atel ets
White Blood Cells
White blood cells are also known as leukocytes.
These make up only a small percentage of the total
number of cells in your blood stream. However,
white blood cells are extremely important to your
body's immune system.
There are two major classes of white blood cells:
Granular leukocytes
There are three types of granular leukocytes;
neutrophils, eosinophils and basophils. Neutrophils
contain digestive enzymes that neutralise bacteria
invading the body, eosinophils contain enzymes
that digest viruses that antibodies in the blood have
bound to and basophils release histamine in order to
intensify allergic reactions, protecting the body from
any parasites.
Agranular leukocytes
There are two main types of agranular leukocytes
– monocytes and lymphocytes. Monocytes develop
into microphages and engulf and ingest pathogens
from infections and wounds. Lymphocytes include B
cells that produce antibodies to fight of infections by
pathogens and T cells that fight off viral infections.
IGNIS
11