H.
BTEC L3 EXTENDED DIPLOMA IN APPLIED SCIENCE
Unit 12: Diseases and Infection
Assignment 12D: Understand how the Human body response to diseases and infections
human body responds to diseases and
Diseases and infections that arise in the body are fought off
infections by the immune system: the body’s defence system.
The immune system is comprised of two sub-divisions, the
non-specific immune system, and the specific immune
system. Both these systems work to defend the body
against diseases and infections.
In this assignment, the mechanism of action for these
immune systems will be explained in terms of how and why
they work to defend the body. In addition to this, responses
involved in the specific immune system will be compared
and evaluated, looking at their roles and the speed and
specificity of their response. Specific named examples of
diseases and infections will be used in this evaluation to
identify how the immune system defends the body.
Defence mechanisms Figure 1- Diagram of the non-
specific defence system (6)
Non-specific
The first line of defence is the
non-specific immune system (see
Figure 1), and these defences
include physical, chemical
barriers and phagocytosis. They
are non-specific as they do not
fight certain types of pathogens
and are general (1).
1
, H.
BTEC L3 EXTENDED DIPLOMA IN APPLIED SCIENCE
Unit 12: Diseases and Infection
The physical barriers of the non-specific immune system barrier of the non-specific immune system (1). The
are the skin and the nose. The skin covers the majority of stomach is part of this non-specific line of defence as it
the body’s surfaces which helps to prevent infection from produces hydrochloric acid, a strong chemical that can kill
pathogens (1). It is a thick layer of dead cells in the pathogens caught in mucus in the airways/pathogens
epidermis, acting as a physical barrier. Normally, when the consumed in food/water (1). The hydrochloric acid in the
skin is exposed when cut/grazed, it can heal itself by stomach is another chemical barrier in the non-specific
forming a scab that acts as a physical barrier, preventing immune system that prevents infections from pathogens.
pathogenic infections (1). The nose is another physical This defence is suitable in its purpose of defending the
barrier as it contains internal nasal hairs, preventing body as it prevents body cells from becoming infected by
infection from pathogens (1). When pathogens enter, they pathogens as they are destroyed by these chemical
adhere to the wet surface of nasal hairs, preventing them barriers.
from reaching the lungs, so they do not cause infection. In
addition, mucus is produced in the nose by cells that trap Phagocytosis is a mechanism that is
invading pathogens before they can enter the lungs (1). part of the non-specific immune Figure 2- Diagram of phagocytosis (1)
The mechanism of blowing the nose removes mucus, system, and this is the second line
including any pathogens trapped in the mucus of the nose of defence in place for when
(1). This defence is suitable for its purpose of defending the pathogens manage to pass the first
body as it prevents pathogens from entering the body line of defence, entering the body-
further by acting as a physical barrier. refer to Figure 2. To start this
process, a pathogen is detected by
The chemical barriers of the non-specific immune system a phagocyte- a type of white blood
are the mouth, eyes, trachea and bronchi, and stomach. cell that engulfs pathogens (1). The
The mouth produces saliva that acts as a chemical barrier pathogen has a specific antigen on
as they consist of antimicrobial substances containing its surface known as PAMPs (Pathogen Associated
lysozymes that break down bacterial cell walls. The eyes Molecular Patterns)- antigens are molecules that trigger an
are another form of a chemical barrier as they secrete immune response. These PAMPs help phagocytes to
tears from tear ducts that consist of antibacterial enzymes, identify pathogens that invade the body as phagocytes
helping to protect against infections from pathogens, e.g., have specialist receptors on their cell-surface membrane,
bacteria (1). The trachea and bronchi have cells known as PRRS (Pathogen Recognition Receptors) that bind and
cilia that work by moving mucus and pathogens towards attach to PAMPS. In addition to this, molecules called
the throat where they are swallowed into your stomach (1). opsonin, e.g., antibodies may coat the pathogen so that
The mucus is formed by goblet cells in the airways so that phagocytes can easily bind. The binding of PRRs to PAMPs
pathogens are trapped- this mucus formed is a chemical activates the phagocyte which causes it to engulf the
2
BTEC L3 EXTENDED DIPLOMA IN APPLIED SCIENCE
Unit 12: Diseases and Infection
Assignment 12D: Understand how the Human body response to diseases and infections
human body responds to diseases and
Diseases and infections that arise in the body are fought off
infections by the immune system: the body’s defence system.
The immune system is comprised of two sub-divisions, the
non-specific immune system, and the specific immune
system. Both these systems work to defend the body
against diseases and infections.
In this assignment, the mechanism of action for these
immune systems will be explained in terms of how and why
they work to defend the body. In addition to this, responses
involved in the specific immune system will be compared
and evaluated, looking at their roles and the speed and
specificity of their response. Specific named examples of
diseases and infections will be used in this evaluation to
identify how the immune system defends the body.
Defence mechanisms Figure 1- Diagram of the non-
specific defence system (6)
Non-specific
The first line of defence is the
non-specific immune system (see
Figure 1), and these defences
include physical, chemical
barriers and phagocytosis. They
are non-specific as they do not
fight certain types of pathogens
and are general (1).
1
, H.
BTEC L3 EXTENDED DIPLOMA IN APPLIED SCIENCE
Unit 12: Diseases and Infection
The physical barriers of the non-specific immune system barrier of the non-specific immune system (1). The
are the skin and the nose. The skin covers the majority of stomach is part of this non-specific line of defence as it
the body’s surfaces which helps to prevent infection from produces hydrochloric acid, a strong chemical that can kill
pathogens (1). It is a thick layer of dead cells in the pathogens caught in mucus in the airways/pathogens
epidermis, acting as a physical barrier. Normally, when the consumed in food/water (1). The hydrochloric acid in the
skin is exposed when cut/grazed, it can heal itself by stomach is another chemical barrier in the non-specific
forming a scab that acts as a physical barrier, preventing immune system that prevents infections from pathogens.
pathogenic infections (1). The nose is another physical This defence is suitable in its purpose of defending the
barrier as it contains internal nasal hairs, preventing body as it prevents body cells from becoming infected by
infection from pathogens (1). When pathogens enter, they pathogens as they are destroyed by these chemical
adhere to the wet surface of nasal hairs, preventing them barriers.
from reaching the lungs, so they do not cause infection. In
addition, mucus is produced in the nose by cells that trap Phagocytosis is a mechanism that is
invading pathogens before they can enter the lungs (1). part of the non-specific immune Figure 2- Diagram of phagocytosis (1)
The mechanism of blowing the nose removes mucus, system, and this is the second line
including any pathogens trapped in the mucus of the nose of defence in place for when
(1). This defence is suitable for its purpose of defending the pathogens manage to pass the first
body as it prevents pathogens from entering the body line of defence, entering the body-
further by acting as a physical barrier. refer to Figure 2. To start this
process, a pathogen is detected by
The chemical barriers of the non-specific immune system a phagocyte- a type of white blood
are the mouth, eyes, trachea and bronchi, and stomach. cell that engulfs pathogens (1). The
The mouth produces saliva that acts as a chemical barrier pathogen has a specific antigen on
as they consist of antimicrobial substances containing its surface known as PAMPs (Pathogen Associated
lysozymes that break down bacterial cell walls. The eyes Molecular Patterns)- antigens are molecules that trigger an
are another form of a chemical barrier as they secrete immune response. These PAMPs help phagocytes to
tears from tear ducts that consist of antibacterial enzymes, identify pathogens that invade the body as phagocytes
helping to protect against infections from pathogens, e.g., have specialist receptors on their cell-surface membrane,
bacteria (1). The trachea and bronchi have cells known as PRRS (Pathogen Recognition Receptors) that bind and
cilia that work by moving mucus and pathogens towards attach to PAMPS. In addition to this, molecules called
the throat where they are swallowed into your stomach (1). opsonin, e.g., antibodies may coat the pathogen so that
The mucus is formed by goblet cells in the airways so that phagocytes can easily bind. The binding of PRRs to PAMPs
pathogens are trapped- this mucus formed is a chemical activates the phagocyte which causes it to engulf the
2
