Unit 12: Diseases and Infection
D: Understand how the human body responds to diseases and
infections.
[IMAGE1]
Ajmal Shekeb NOORMAL
,Assignment 12D Ajmal Shekeb NOORMAL
Scenario
I am completing a clinical work experience placement where I am shadowing the work of a
healthcare science team within their immunology department. The science of clinical
immunology is a fast-developing area of the NHS and the immunology department wishes to
promote the vocational opportunities available in this field via the NHS Practitioner Training
Programme and their own clinical work experience placements programme. My role is to
prepare information leaflets and posters relating to human immune defences; these will be
used as part of the student induction programme.
Specific and non-specific immune responses:
Immune system, the complex group of defence responses found in humans and other
advanced vertebrates that helps repel disease-causing organisms (pathogens). Immunity
from disease is actually conferred by two cooperative defence systems, called nonspecific,
innate immunity and specific, acquired immunity. Nonspecific protective mechanisms repel
all microorganisms equally, while the specific immune responses are tailored to particular
types of invaders. Both systems work together to thwart organisms from entering and
proliferating within the body.[13]
The innate, or non-specific, immune response is the initial line of defence against non-self-
pathogens. Physical, chemical, and cellular defences against infections make up the innate
immune response. The primary goal of the innate immune response is to stop invading
infections from spreading and moving throughout the body. [14]
The majority of microorganisms encountered in ordinary life are resisted before they create
illness symptoms. Because these potential pathogens, which include viruses, bacteria,
fungus, protozoans, and worms, are so diverse, an organism can benefit from a generic
defence mechanism that diverts all forms of this complex microscopic horde. Physical
barriers such as the skin, chemical barriers such as antimicrobial proteins that hurt or
destroy intruders, and cells that target foreign cells and body cells harbouring infectious
pathogens are all examples of nonspecific protection provided by the innate immune
system.[13]
Adaptive immune response is the second line of defence against non-self-pathogens. Only
vertebrates have adaptive immunity, which is also known as acquired immunity or specific
immunity. The adaptive immune response is tailored to the pathogen. The adaptive immune
response is designed to fight non-self-pathogens, but it can also harm itself. Autoimmune
disorders can arise as a result of this (e.g., lupus, rheumatoid arthritis). [14]
The body has a number of nonspecific methods of fighting infection that are called early
induced responses. They include the acute-phase response and the inflammation response,
which can eliminate infection or hold it in check until specific, acquired immune responses
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, Assignment 12D Ajmal Shekeb NOORMAL
have time to develop. Nonspecific immune responses occur more rapidly than acquired
immune responses do, but they do not provide lasting immunity to specific pathogens.[13]
Nonadaptive immune responses rely on a number of chemical signals, collectively called
cytokines, to carry out their effects. These cytokines include members of the family of
proteins called interleukins, which induce fever and the acute-phase response, and tumour
necrosis factor-alpha, which initiates the inflammatory response.[13]
[14] Line of Timeline Cells Antigen Examples
Defenc Dependenc
e y
Innate First Immediate Natural killer Independent Skin, hair,
(non- response (0 - cells, cough, mucous
specific) 96 hours) macrophages, membranes,
neutrophils, phagocytes,
dendritic cells, granulocytes
mast cells,
basophils,
eosinophils
Adaptive Second Long term T and B Dependent Pus, swelling,
(specific) (>96 hours) lymphocytes redness, pain, T
and B
lymphocyte
response
While the innate immune response is immediate, the adaptive immune response is not.
However, the effect of the adaptive immune response is long-lasting, highly specific, and is
sustained long-term by memory T cells.[14]
Physical barriers to infection:
The body is continually protecting itself against pathogen assault. Stopping pathogens from
entering your body is the first line of defence against infection. These first lines of defence
are generic defences that aren't tailored to specific pathogen kinds. This is referred to as
non-specific barriers, and they might be physical or chemical in nature. [3]
Physical barriers are vital in keeping microorganisms from reaching infection-prone organs.
At the cellular level, barriers are made up of closely bound cells that prevent invaders from
penetrating deeper tissue. The endothelial cells that line blood vessels, for example, have
extremely tight cell-to-cell contacts that prevent pathogens from entering the circulation.
Cell junctions are made up of cell membrane proteins that connect to the extracellular
matrix or complementary proteins from nearby cells. Different types of cell junctions can be
found in numerous tissues throughout the body. Invading microorganisms may attempt to
break down these substances chemically, using enzymes such as proteases that can cause
structural damage to create a point of entry for pathogens. [1]
The epidermis of the skin comprises a thick layer of dead cells that acts as a physical barrier.
Microbes are removed from the epidermis by shedding it on a regular basis. Mucus is
produced by the mucous membranes, which traps germs. Microbes, dust, and pollutants are
filtered out of the air by hair in the nose. Cilia borders the upper respiratory system,
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