The immune system is vital for the life of humans and
works constantly, but not always quietly, behind the scenes to keep our blood
stream free from potentially dangerous foreign organisms. The methods by which
it can achieve this are ingenious. The immune system is composed of specialist
blood cells called lymphocytes which have the ability to detect anything in
the blood stream that is non-self and destroy it.
The recognition of self and non-self matter forms
the basis of immunity and the distinction between the two means that our immune
systems can attack foreign (non-self) matter and leave the cells and molecules
of the human body (self) free to carry out their functions. However, the immune
system does not solely consist of these white blood cells but includes many
of the major organs of the body and lymphocytes could be described as our last
line of defence. Our first line of defence involves the human bodys largest
organ, the skin.
It would have been impossible the evolution of the human
race reach the advanced stage it is today, if our skin had been permeable to
bacteria. The linings of our respiratory tract are also involved as they secrete
a layer of mucous which helps to trap any bacteria that may have entered our
body while we breath. Another major aspect of our immune systems is our digestive
system as many bacteria find it easy to enter the body whilst being carried
by food. Therefore it is important that conditions in the small and large intestines
are maintained to prevent these bacteria from causing damage the intestines
or entering the blood stream. This aspect of immunity will be discussed in further
detail later in the article.
The Blood Stream
It is said that the ferocity of the reaction of white
blood cells on bacteria is similar to that of a Piranha fish in response to
food. They have the ability to detect tiny protein fragments released by the
bacteria and migrate to their location within seconds. Once they reach the bacteria,
they can kill by using one of two methods. The first method is to attach to
the bacteria and release toxic compounds which would kill them. If however,
the bacteria are too strong for this kind of attack, the white blood cell will
engulf and digest it.
The immune system of the blood stream also possesses
another type of specialised cell called a memory cell. Once a new type of bacteria
has been destroyed by the immune system these cells will remember that specific
strain. This means that should the bacteria enter the bloodstream in the future,
the immune system will recognise it destroy it before it can cause harm. It
is for this reason that we only get measles once!
The reason why the common cold is never dealt with in
the same swift manner is because this strain of bacteria is constantly evolving.
This means that each new outbreak is caused by a bacteria which is not recognised
by the memory cells, even though the average person has at least one cold
each year. It is only when the bacteria have invaded the body and been allowed
to multiply, due to an impaired immune system, that infections result and symptoms
The symptoms that we experience are all a response by
the immune system in an attempt to remove the bacteria from the body. Coughing,
sneezing and an increased production of mucous by the lungs, throat and nose
are attempts by the body to get rid of unwanted bacteria. There are certain
nutrients which have been shown to enhance the function and production of white
blood cells. Some studies have shown that vitamin C can increase the production
of white bloods cells in the bone marrow and herbal supplements, such as echinacea
and green tea, have been shown to enhance the production of toxins which the
immune cells use to kill bacteria. Vitamin A can help to maintain the mucous
membranes and allow an efficient production of mucous.
The Digestive System
As well as facilitating the delivery of nutrients to
the body, the digestive system forms the largest fraction of the entire human
immune system, it has the task of screening the content of the intestines for
possible pathogens or other unwanted invaders. Our digestive system is home
to approximately 400 different species of bacteria and each person has around
100 trillion bacteria in their intestines, accounting for 1-1.5kg of total body
weight. The gut flora plays an important role in maintaining normal intestinal
function, however not all bacteria are beneficial.
The health of the digestive system is dependent on maintaining
a delicate balance between the desirable and undesirable bacteria found in the
gut. When this balance is disrupted, disease and inflammation can occur as a
result of an overgrowth of pathogenic bacteria, compromising the functioning
of the digestive system. Pathogenic bacteria produce infectious diseases by
invading tissues, excreting antigens and/or toxins that damage tissues. Levels
of pathogenic bacteria can reach as high as 85% of total floral composition;
some common examples include Bacillus coli, Candida albican, Escheria coli and
If pathogenic bacteria predominate in the digestive system,
a range of adverse health effects can result. These include diarrhoea, disrupted
bowel rhythm, nutrient deficiencies, poor digestion and impaired absorption.
Beneficial bacteria, also known as probiotics, include Lactobacillus acidophilus,
Bifobacterium bifidus and Lactobacillus casei. Probiotics are capable of maintaining
the proper balance of the intestinal flora by competing out potentially pathogenic
bacteria (undesirable bacteria). Probiotics reduce the presence of undesirable
bacteria by competing for adhesion sites and nutrients, producing anti-microbial
substances and lowering the pH of the digestive tract through the production
of short chain fatty acids.
Probiotics stimulate the intestinal immunologic barrier,
and also have a role in controlling food allergies. The immune stimulating effect
of probiotics also helps to maintain the floral balance, through the removal
of pathogenic bacteria by the immune system.
The composition of the diet can influence the microflora
of the digestive tract and the inclusion of certain factors can promote and
support the presence of probiotic strains. A diet rich in whole grains and fresh
fruit and vegetables and high in complex carbohydrates and fibre help beneficial
bacteria to break down food and encourages the production of short chain fatty
acids, which have several benefits at the level of the colon including reducing
pH and energy production. Fermented foods such as cultured yoghurt, cottage
cheese, live yoghurt and other soured milk products all contain certain types
of the beneficial bacteria and so their consumption can help replenish levels
in the gut. There are also factors that can deplete levels of beneficial bacteria;
the measures implemented in destroying pathogenic bacteria such as the use of
pesticides and the cooking of foods also destroys probiotic bacteria.
Diets that are too high in sugar and too low in natural
soured milk products can reduce the ratio of good to bad bacteria. An excessive
intake of alcohol and the use of certain drugs, such a broad-spectrum antibiotics,
non-steroidal anti-inflammatory medication and oral contraception, can reduce
levels of beneficial bacteria in the body. The most natural way of ingesting
large concentrations of good bacteria is with our foods. However, the activities
involved in the processing and preparation of food can be detrimental to the
beneficial bacteria found in fresh goods and foods that are rich sources of
beneficial bacteria, such as Camembert cheese, sauerkraut and yoghurt are not
usually present in the diet in great quantities.
Additionally, the quantity of bacteria required for any
preventative or therapeutic effect is beyond the amount that could conceivably
be provided by the diet. For example, a person would have to consume a litre
of yoghurt to obtain between 1 and 10 billion bacteria whereas as probiotic
supplements can provide as much as 2 billion bacteria in a single capsule.
In summary, the immune system consists of a number of
organs of the body which are all working to ensure that the body is kept free
from pathogenic, and some potentially life threatening bacteria. However, dietary
steps can be taken to aid our bodys defences against these bacteria which is
especially essential during the winter months. Along with a diet rich in fresh
fruit and vegetables, there are a number of supplements which can be taken that
may further increase the efficiency of our immune system.
These include: Vitamin C (High Strength) Vitamin
A Zinc Probiotics (Friendly bacteria) Echinacea Goldenseal Green Tea Cats Claw
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