Introduction
My role as a member of a healthcare scientific team's immunology department's shadowing
programme is to create educational leaflets and posters that are focused with human defence. The
body is protected from dangerous microorganisms and illnesses by the intricate network of cells,
tissues, and organs that make up the immune system in humans. Clinical immunology is a rapidly
expanding area of medical study that focuses on the identification, therapy, and management of
immune system illnesses.
→P5 ←
Non- Specific defence
The innate immune system, also known as the non-specific defence, is a group of mechanisms that
aid in defending the body against external invaders such as bacteria, viruses, fungi, and parasites.
This is because the first line of protection against infections is these defences. Therefore, the a
non-specific consists of cellular defence, chemical defence, and physical barriers.
Physical barrier → The first line of protection against invading diseases is physical barriers.
The skin is the largest physical barrier in the body, and as a result, it serves as a barrier that stops
viruses from entering the body. The mucous membranes, which line the respiratory, digestive, and
urinary tracts, are also physical barriers that prevent pathogens from entering the body. This
indicates that these physical barriers contribute to limiting the entry of foreign substances into the
body, hence lowering the risk of infections.
Skin: The skin which is the largest organs in the body help to sever as a physical barrier against
pathogen. The epidermis, dermis, and hypodermis are three layers of packed cells that make up the
skin. As a result, the epidermis, or outermost layer of skin, is a thin layer of densely packed cells that
aid in protecting the body from harmful substances including heat, cold, and injury to the body. A
thicker layer of dermis, which is composed of blood vessels, nerves, sweat glands, and hair follicles,
lies underneath the epidermis. In addition, the hypodermis, the innermost layer of skin, is fatty and
contains blood and lymphatic veins. (Save My Exams, 2017)
,Mucous membrane: Mucous membranes, commonly known as the thin, moist layers of tissues that
line various bodily structures. In order to defend against harmful pathogens, foreign particles, and
other potentially harmful substances, it provides a physical and chemical barrier. As a result, it is an
essential component of the body's nonspecific defence. The formation of mucus, a thick, sticky fluid
that provides a physical barrier to trap and stop the entry of dangerous microbes including bacteria,
viruses, and fungi into the body, is one of the mucous membranes' main functions. This is due to the
presence of antimicrobial substances in mucus, such as enzymes, antibodies, and other proteins,
which may destroy or neutralise dangerous microorganisms. In order to help move mucus and
pathogens that have been caught in the membrane's surface out of the body, mucous membranes
also include cilia, which are microscopic hair-like projections that line the membrane's surface. By
doing so, the chance of infection is decreased and toxic chemicals are prevented from accumulating.
Mucous membranes have a strong blood supply as a result, making it possible to respond quickly to
infections. This indicates that in reaction to an infection or harm the blood vessels in the mucous
membranes enlarge, allowing more immune cells to enter the afflicted region and combat off the
invaders. (Save My Exams, 2017)
Endothelia: All the blood vessels and lymphatic vessels are lined by endothelium, a single layer of
cells known as endothelia cells. The endothelium is a thin layer of cell that lines the inner surface of
blood vessels and lymphatic vessel which plays an important role that help in protecting the boyd as
a part of non-specific defence system. Therefore, endothelium help the body in many ways such as
protecting the body through its physical barrier function. The endothelial cel form a continuous later
which separated the blood and the lymphatic fluid from the surrounding tissues, which help to
prevent harmful substances from entering the body. This means that the endothelium helps to
regulate the exchange of fluid, electrolytes and other substance between the blood and lying tissues.
In addition, endothelial cells release a number of inflammatory mediators, including cytokines and
chemokines, in response to an infection or damage that draws immune cells to the area. Aside from
releasing adhesion molecules, the endothelial cells also help immune cells stick to blood vessel walls
and move into tissues, where can get rid of infections or fix tissue damage. Additionally, endothelium
is crucial in controlling blood coagulation. This is due to the fact that endothelial cells release a
chemical when a blood vessel ruptures, which encourages the development of blood clots and helps
to limit excessive bleeding. (Johanna Hol Fosse et al., 2021)
, Chemical barrier →Chemical barrier, a part of the body's non-specific defence mechanism,
aids in providing resistance against dangerous substances including bacteria, viruses, and fungi. This
is due to the chemical barrier, which consists of many body-produced substances that may either kill
or limit the growth of certain pathogens. Sebum is thus one of these substances.
Sebum: Sebaceous glands in the skin release sebum, a mixture of lipids that includes triglycerides,
wax esters, squalene, and cholesterol esters. Sebum supports the body's general defences in a
number of ways. This is because sebum aids in preventing pathogen entry into the body. Since
sebum has an oily texture, it is challenging for germs to adhere to the skin and reach the skin's
deeper layers. Moreover, sebum also includes fatty acids, an antimicrobial substance which has been
found to interfere with the growth of a variety of pathogens. Because of the fatty acids in sebum, the
skin's surface has a lower pH, which makes it more susceptible to many pathogens. Additionally,
sebum protects and moisturises the skin, reducing damage and inflammation that might weaken the
skin's protective barrier. As a result, it aids in the body's defence against infection by preventing the
entry and development of possible invaders. (Biology LibreTexts, 2019)
Lysozyme: An enzyme called lysozyme is crucial in defending the body against bacterial infections. It
may be present in tears, saliva, and mucus, among other bodily fluids, and it functions to weaken
various bacteria's cell walls. This is so because bacterial cell walls are made of unique molecules
called peptidoglycan. The mechanism by which lysozyme functions is by catalysing the hydrolysis of
the bonds forming the peptidoglycan's sugar molecules. As a result, the bacterial cell wall becomes
more fragile and finally breaks down, killing the germs. Additionally, lysozyme works especially well
in defending mucosal surfaces, including those around the mouth, nose, and eyes. Lysozyme found in
saliva, tears, and mucus helps to prevent these illnesses since these surfaces are continually exposed
to environmental microorganisms. (Bmrb.io, 2020)
Stomach acid : Gastric acid, commonly referred to as stomach acid, is extremely significant. The body
is protected by stomach acid, which destroys potentially hazardous pathogens in food and drink. This
is due to the pH range of 1-3, which indicates that it is acidic and difficult for bacteria, viruses, and
pathogens to survive. Proteins are broken down into smaller peptides by stomach acid, which aids in
the small intestine's enzyme digestion. This is because harmful proteins that trigger an immune
response are prevented from being absorbed. In addition, stomach acid also helps to denature
toxins and other harmful substances that may be present in food or water. For instance, pepsin is an
enzyme that aids in protein breakdown but also contains antimicrobial properties that aid in
destroying of pathogenic microbes and other harmful organisms. (Newman, 2022)
