IMMUNOLOGY
300 Level/BMLS
University of Jos
By
Abah Michael Idoko
*Immunology First Line of Defense Lecture
Notes*
*Introduction*
The first line of defense, also known as innate immunity, is the
body's initial response to infection or injury. It provides
immediate protection against pathogens, such as bacteria,
viruses, and fungi, and is crucial for preventing infections. This
non-specific defense mechanism is present from birth and is the
same in everyone, providing a general defense against pathogens.
The first line of defense is essential for survival, as it provides
the initial protection needed to prevent infections and allow the
adaptive immune system to develop.
*Physical Barriers*
,The first line of defense includes physical barriers, which are the
body's first line of protection against pathogens. These barriers
prevent pathogens from entering the body and include:
1. *Skin*: The skin is the body's largest organ and provides a
physical barrier against pathogens. It is composed of multiple
layers of epithelial cells that are tightly packed, making it
difficult for pathogens to penetrate. The skin's acidic pH, sweat,
and sebaceous glands also contribute to its antimicrobial
properties. The Sebum oil produced on the skin surface traps
microbes and prevents entry into the body cavities, the cerumen
(ear wax) produced by the ears traps micro organisms from entry
into the system, the lysozymes produced by the tears in the eyes
help to flush out dust particles and contaminants from the eyes.
2. *Mucous membranes*: Mucous membranes line the
respiratory, gastrointestinal, and genitourinary tracts, and
provide a physical barrier against pathogens. They also produce
mucus, which traps pathogens and other foreign particles,
preventing them from entering the body. The hair follicles
within the nasal cavity alongside the production of mucus
prevents penetration of microbial entrance into the system via
sneezing and coughing actions to expel the inhaled substances,
the GIT is operates at a highly acidic pH to enable destruction of
microbial substances that have been ingested , the HCL in the
stomach combats infectious bacteria and parasitic materials by
the stomach enzymes. The vaginal surface has an acidic pH that
, enables the moist surface to fight off microbial invasion to
prevent contraction of infectious agents.
3. *Epithelial cells*: Epithelial cells line the surfaces of the
body and provide a physical barrier against pathogens. They also
produce antimicrobial peptides and proteins that help to kill
pathogens.
4. *Ciliated epithelium*: Ciliated epithelium lines the
respiratory tract and helps to clear mucus and pathogens from
the airways.
Examples of the first line of defense include:
1. *Skin infections*: The skin provides a physical barrier
against pathogens, and the presence of commensal bacteria on
the skin helps to prevent infections.
2. *Respiratory infections*: The mucous membranes in the
respiratory tract provide a physical barrier against pathogens,
and the presence of cilia helps to clear mucus and pathogens
from the airways.
3. *Gastrointestinal infections*: The mucous membranes in
the gastrointestinal tract provide a physical barrier against
pathogens, and the presence of commensal bacteria in the gut
helps to prevent infections.
300 Level/BMLS
University of Jos
By
Abah Michael Idoko
*Immunology First Line of Defense Lecture
Notes*
*Introduction*
The first line of defense, also known as innate immunity, is the
body's initial response to infection or injury. It provides
immediate protection against pathogens, such as bacteria,
viruses, and fungi, and is crucial for preventing infections. This
non-specific defense mechanism is present from birth and is the
same in everyone, providing a general defense against pathogens.
The first line of defense is essential for survival, as it provides
the initial protection needed to prevent infections and allow the
adaptive immune system to develop.
*Physical Barriers*
,The first line of defense includes physical barriers, which are the
body's first line of protection against pathogens. These barriers
prevent pathogens from entering the body and include:
1. *Skin*: The skin is the body's largest organ and provides a
physical barrier against pathogens. It is composed of multiple
layers of epithelial cells that are tightly packed, making it
difficult for pathogens to penetrate. The skin's acidic pH, sweat,
and sebaceous glands also contribute to its antimicrobial
properties. The Sebum oil produced on the skin surface traps
microbes and prevents entry into the body cavities, the cerumen
(ear wax) produced by the ears traps micro organisms from entry
into the system, the lysozymes produced by the tears in the eyes
help to flush out dust particles and contaminants from the eyes.
2. *Mucous membranes*: Mucous membranes line the
respiratory, gastrointestinal, and genitourinary tracts, and
provide a physical barrier against pathogens. They also produce
mucus, which traps pathogens and other foreign particles,
preventing them from entering the body. The hair follicles
within the nasal cavity alongside the production of mucus
prevents penetration of microbial entrance into the system via
sneezing and coughing actions to expel the inhaled substances,
the GIT is operates at a highly acidic pH to enable destruction of
microbial substances that have been ingested , the HCL in the
stomach combats infectious bacteria and parasitic materials by
the stomach enzymes. The vaginal surface has an acidic pH that
, enables the moist surface to fight off microbial invasion to
prevent contraction of infectious agents.
3. *Epithelial cells*: Epithelial cells line the surfaces of the
body and provide a physical barrier against pathogens. They also
produce antimicrobial peptides and proteins that help to kill
pathogens.
4. *Ciliated epithelium*: Ciliated epithelium lines the
respiratory tract and helps to clear mucus and pathogens from
the airways.
Examples of the first line of defense include:
1. *Skin infections*: The skin provides a physical barrier
against pathogens, and the presence of commensal bacteria on
the skin helps to prevent infections.
2. *Respiratory infections*: The mucous membranes in the
respiratory tract provide a physical barrier against pathogens,
and the presence of cilia helps to clear mucus and pathogens
from the airways.
3. *Gastrointestinal infections*: The mucous membranes in
the gastrointestinal tract provide a physical barrier against
pathogens, and the presence of commensal bacteria in the gut
helps to prevent infections.
