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BTEC unit 12 - diseases and infections assignment D
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BTEC applied science unit 12 assignment D grade distinction
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Assessment DAmber James 10266480
For our bodies to stay healthy from dangerous bacteria and viruses they need to
be able to fight and become immune. To do this they create different responses.
Non-specific immunity is where the body will protect the immune system from
any bacteria or viruses. They are classed as the body’s first line of defence, and
they can include skin, stomach, eyes, and bladder. The skin, epidermis, protects
the body by blocking bacteria, viruses, and any harmful substances from getting
into the body, and it keeps important nutrients that the body needs from leaking
out. The epidermis is the top, thin layer of the skin, for places on the body that
might endure more wear, the epidermis is thicker to protect further. The skin also
produces sebum that can lower the pH of bacteria to make it safer for the body
to handle if it ever invades (Myer, 2018). The stomach is an important part in
protecting the body, it does this by releasing enzymes that break down proteins
in food, it then releases hydrochloric acid which kills any microorganisms that
have been on your food. Not only does it protect your body, but it protects itself
by lining the walls in mucus with a neutral pH to prevent the enzymes destroying
the stomach (BBC, n.d.). The eyes have many different aspects that protect the
body from harm, these include, eyelashes (catching any particles that come near
the eye to prevent it entering and causing someone to blink), tears (tears are
salty which help clean the eye, and they contain antibodies that prevent
infection), and the orbit (the bone socket that the eye ball is located in to prevent
damage from objects hitting the eye area) (Garrity, 2022). The bladder is
constantly picking up unwanted products from our body and flushing it away, this
prevents any bacteria from fully forming and developing in the tract.
Sometimes bacteria can pass through the defence and enter the body. Luckily
our body knows how to fight back. The second line of defence include an
inflammatory response, blood clotting and phagocytosis. The inflammatory
response is activated when tissue is injured either by bacteria, heat, and/or
trauma. When the body detects an invasion it sends out cytokines, these
cytokines promote more inflammation to trap the germs and begin healing the
injury. This will cause redness, swelling, and moderate pain. This response can be
brought on by a foreign object entering the body and releasing microorganisms
into the bloodstream. Once there is an injury, white blood cells rush to the area
to begin fighting, for inflammation they release a chemical called histamine to
dilate capillaries and arterioles. This then causes blood to rush faster to the
affected area, which in turn brings more phagocytes with them. Neutrophiles can
then enter the infected area through the capillaries and destroy the bacteria
(Britannica, 20204).
Phagocytosis is when phagocytes intake
particles to carry them away from the infection
and destroy them. The way it can engulf cells is
by having the correct binding site, if they don’t it
won’t happen. This also does not occur unless
the foreign cell and phagocyte are in contact.
There are many different receptors that will bind
to specific phagocytes, opsonin receptors are
used with bacteria that has been covered in
immunoglobulin G antibodies. The body coats
, these cells in antibodies to make white blood cells aware they are foreign and
need to be destroyed. Scavenger receptors target bacteria molecules due to
bacteria having a matrix surrounding them, this makes it easier for the body to
identify the threat because human cells do not have the same structure. Some
cells are able to make antibodies that will then bind to antigens from the
infection, this makes it easier for the body to know how and what it needs to
fight. The process of a cell phagocytizing can happen for many different cells, for
example, for a macrophage to phagocytize it needs to correctly follow these
steps:
1. The first step is having the foreign cell (which we will call a virus) and the
macrophage cell to physically encounter each other. One way they can
move together is by cytokines. These are proteins used to aid in cell
signalling, this helps when an infection is in a specific area (infected elbow
cut).
2. Secondly, the microphages receptors help bind the virus to surface. This is
where phagocytosis begins, however it will only start if the bonding was
successful. Sometimes, when tackling a virus, the virus will exploit the
host cell by tricking the cell into engulfing it. This then enables the virus to
replicate and spread. Once this has happened the host cell is then infected
and classed as foreign, therefore the body will treat it as a virus and begin
to destroy it.
3. next the macrophage begins to absorb the virus. It does this by
using pseudopods from the cytoplasm to surround
the cell. They can expel ‘arms’ and cover the virus
because the host cell is flexible and full of fluid.
4. This entails that the virus is surrounded in a bubble called
phagosome. The virus has a pocket of cytoplasm keeping
it safe within the macrophage.
5. After that, the phagosome bonds with a lysosome to make a
phagolysosome. It does this because without the lysosome it would not be
able to destroy the virus. The lysosomes’ role is to clear the waste from
cells, this is done by lowering the pH inside the cell which makes the virus
neutral or die, so it does not affect the cell.
6. The waste is then expelled from the cell via exocytosis.
(Academy, n.d.)
There are 3 mechanisms that help prevent major loss of blood. Vascular
spasm, when the walls of the blood vessels contract to slow the blood flow
until other mechanisms begin to work. Platelet plug formation, when an
area is damaged platelets will become sticky and plug the area to stop
blood flowing. Coagulation, when proteins and enzymes transform blood
plasma solid to pause red blood cells and plug blood vessels. There is a
cascade mechanism with blood clotting that starts with thromboplastin
being released from the damaged tissue. As thromboplastin is an enzyme
it can catalyse due to calcium ions, this then causes prothrombin (inactive)
to be turned into thrombin (active). Fibrinogen is then converted to fibrin
that makes fibres; this happens when thrombin catalyses. These fibres
become mesh that captures platelets and red blood cells to create a clot
(Evans, 2023).
There is then a humoral response that b-lymphocytes and antibodies are needed
to help fight infections. This is classed as specific immunity. The B cells that are
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