This is a DISTINCTION assignment marked by Pearson BTEC exam board. It is learning aim D- understand how the human body responds to diseases and infections.
Please use this assignment as a guide and do not copy and paste as you will be marked down by the examiners due to PLAGIARISM.
UNIT 12-DISEASES AND INFECTION
Learning aim D: Understand how the human body responds to diseases and
infections.
INTRODUCTION
A pathogen is a microorganism which causes diseases. There are different types of pathogen
virus, bacteria, parasites and fungi. A bacteria is a microscopic pathogen, single-cell
organisms that quickly reproduces as soon as it enters the body. Bacteria are prokaryotic
cells which produces harmful toxins and causes inflammation. Virus is an infectious microbe
which can cause deadly diseases. It reproduces by being in control of the host cell and
reproduces the virus. Viruses are considered non-living as to reproduce they a host
otherwise they cannot reproduce by themselves. Parasites are organism that lives on or in a
host organism. They are normally specialised organism from their host. Parasites either live
on host surface or inside the host body. Fungi is a eukaryotic cell, single cell or multicellular
organisms; it can be found everywhere on the land such as soil or plant material.
Medicine helps to prevent infection through vaccines which contains a deadly virus or
weaken version of a disease which protects the human body from infectious diseases.
Another effective medicine against infectious diseases are antibiotics and antivirals which
kill the bacteria or stop it from reproducing. Hygiene is another important aspect for
preventing infection as it can prevent a person getting an infectious disease. For instance,
washing your hands with soap and warm water every time a person touches a surface can
prevent getting a disease and spread the disease. Handling food and prepare it correctly can
prevent infections spreading around such as salmonella.
The immune system protects the human body from infectious diseases entering our body.
An antigen is microbe which can consist of bacteria, virus, chemicals or other substances
outside the body. When an infectious disease enters the body antigens our immune system
produces antibodies to fight the disease. It will then store the information about the disease
and next time that the disease tries to invade the body it will fight off the disease. The
immune system is important as it allows us to have a healthy life, help us maintain healthy
tissue and help us fight the disease or pathogens.
The aim of this report is to explain specific and non-specific defences on how it protects the
body, compare the roles of specific and non-specific mechanisms in the body and evaluate
the roles of cell mediated and humoral responses.
SPECIFIC DEFENSE MECHANISM
Specific defence mechanism also known as adaptive immunity the antibodies have the
ability to immunise the body against specific pathogens or antigens. Antigens are proteins
or substances where your immune system produces antibodies against a specific infection.
They are able to distinguish different pathogens as a result they work slowly as they need to
identify which pathogen is which and because the lymphocytes that controls the pathogen
need to build up their numbers and this takes time. This defence mechanism allows the
, pathogens to remember the pathogen in order to make a strong response for the next time
the pathogen enter the body. There are two types of specific defence: cell mediated
immunity and humoral immunity. Cell mediated immunity occurs when T-lymphocytes also
called T-cells they are active when the pathogen is exposed. The first defence mechanism of
our immune system is lymphocyte which are white blood cells. There are 3 main types of
lymphocytes T-cells, B cells and natural killer cells. B-cells are found in blood stored in lymph
nodes, are covered in antibody surface receptors and they respond to antigen. T-cells are
found in thymus and they focus on targeting the specific antigen. Natural killer cells are
known for rapidly killing infected pathogens, detecting and controlling any signs of cancer.
NON-SPECIFIC MECHANISM
Non-specific mechanism also known as innate immunity is the first line of defence so it
treats all pathogens the same so they respond quickly as the body responds immediately as
it will recognise the pathogen. Examples of non-specific defence are skin, mucus, cilia, acid
and fever. The skin is a strong physical barrier, mucus traps all pathogens from the outside,
cilia small hair found in the airways which pushes the mucus away from the lungs and the
acid found in the stomach or urine kills pathogens.
The phagocyte is attracted to the pathogens via chemicals, and it will move toward the
pathogen. The phagocyte has specific receptors on its surface membrane which attracts the
pathogen found on the surface. The lysosomes found in the phagocyte moves towards the
phagosome formed by engulfing the pathogen. Digestion of ingested microbe by enzyme
then residual body forms containing indigestible material and then there is a discharge of
waste material. Macrophages are phagocytes cells also known as monocytes formed in the
bone marrow and later circulate in the blood.
Inflammation occurs to protect the human body against infected microorganisms. So,
substances in our white blood cells enter our blood or tissue to protect the body. As a result,
in the area of injury the blood flow raises around it which causes redness or warmth. There
could be some side effects such as fluid leaking into our tissues which will be seen as
swelling this can cause pain and trigger nerves. There are two types of inflammation acute
and chronic. Acute inflammation is when our body cells begin a healing process when there
is sudden damage in our body such as cutting our finger. Our body cells will send
inflammatory cells to the injury. Chronic inflammation is when our body cells carry on
sending inflammatory cells when there is no infection it can last for many months or years.
Abdominal pain and chest pain are examples of chronic inflammation.
A fever is a rise in temperature and it occurs when a microorganism invades hypothalamus.
As a result, this reduces the pathogens to reproduce quickly. A person has fever because
they have an infection so the body is trying to kill the virus or bacteria this is when our
immune system activates.
Interferon are proteins which are part of defence mechanism and indicate our immune
system that there are germs or cancer cells in our body. Infected cells release a chemical
called interferon when our healthy cells have been invaded by germs. The immune system
will be able to recognise the infected pathogens as interferon is producing interferon that
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