Download blood cells - School

Plasma and cells in suspension
If blood is separated it no longer looks like the red liquid that we recognise.
centrifuge
55%
45%
The blood sample separates into two parts.
The top half is a straw coloured liquid called plasma.
The bottom half is a dark collection of blood cells.
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Products dissolved in plasma
Blood has to rely on its plasma to transport some of these useful or waste products.
For example, plasma carries CO2 from the cells to the lungs.
blood flowing along a
capillary
plasma
CO2
CO2
blood cell
CO2
CO2
CO2
blood cell
Dissolved digestive products
The third and fourth roles are also centred around the moving of a substance
from one place to another.
Plasma is responsible for carrying dissolved food.
Remember!
Our digestive system breaks down the food we eat to release the useful nutrients.
Leaving the plasma
The soluble food dissolves into the plasma and is carried from the small intestine to
the cells of the body.
Here they diffuse into the cells and are used in various chemical reactions.
glycerol
sugars
amino acids
plasma
body cell
fatty acids
Removing urea
The final role of the plasma is to carry a particular waste product from the liver to
the kidneys.
The waste product is called urea.
Urea is made in the liver by the breakdown of amino acids.
As urea is toxic, it must be removed from the body as quickly as possible!
The blood now has to help the body do this.
The full load
All this is being carried in just the plasma!
white blood
cell
platelets
fatty
acids
sugar
red blood cell
amino
acids
urea
carbon dioxide
Image of the 3 constituents
red blood cells
white blood cells
platelets
Inside
the
red
blood
cells
Actually, although the red blood cell is a “cell”, it does not contain
one of the 3 parts of a “normal” cell.
Red blood cells have no nucleus.
This may seem odd but, there is a reason for it.
Red blood cells also contain a unique substance called haemoglobin.
This is a special iron based pigment whose presence is essential if the red
blood cell is to perform its job.
Fe2+
Inside the alveoli
Here is a close up showing the diffusion of oxygen gas.
As the oxygen gas diffuses across the lining of the alveolus, it dissolves in the moist
layer.
This speeds up the diffusion process.
moist layer
O2
lining of alveolus
lining of capillary
red blood cell
O2
Oxyhaemoglobin
If we now concentrate on one red blood cell, we can see how important the
haemoglobin molecule is to the process of transporting oxygen.
The oxygen molecule diffuses into
the red blood cell.
each red blood cell
contains the pigment...
Haemoglobin
+
O2
Oxyhaemoglobin
These two molecules bind together to
produce this new substance.
Oxygen diffusion at the capillary
bed
White blood cell
Let’s now consider the white blood cell.
The white blood cell is bigger than the red blood cell.
It has a much more varied shape and there are different types of white blood
cell within the blood.
Role in defence
White blood cells play a part in the defence system of the body.
There are far fewer white blood cells within the blood compared with red blood cells.
They are designed to fight microbes such as bacteria and viruses.
Match the cells to the correct
functions
Methods of attacking microbes
As we saw when we covered the blood system, white blood cells are found in blood.
They have a nucleus, which can vary in shape from one sort of white blood cell to the
next.
They have 3 main methods of attacking microbes.
1. Producing antitoxins
Remember that microbes can cause an infected person to feel ill by releasing toxins
(poisons). The first way white blood cells defend the body is by releasing antitoxins.
These chemicals are designed to neutralise the effects of the toxins and render them
harmless.
Methods of attacking microbes
2. Ingesting Microbes
Some white blood cells actually ingest (eat) the microbes and then break them down
once they are inside the cell. The microbe is destroyed by powerful digestive enzymes,
which are released within the cytoplasm of the white blood cell.
white
blood cell
microbe
The white blood cell surrounds the
microbe.
Methods of attacking microbes
3. Releasing antibodies
As well as releasing antitoxins, the
white blood cell can
release another chemical known
as an antibody.
Antibodies - you can
think of them as target
specific bombs.
Their shape is important
because it fits exactly onto a
site on the microbe.