THE THREE LINES OF DEFENCE

There are “Three lines of Defense” that all contribute to the Immune System ,each an

important part in the destruction of Pathogens

(Pathogens are any foreign substance found in the body that causes an Immune Response)

First Line of Defense

SkinThick layers of Skin make

the penetration of Pathogens nearly Impossible

The First Line of DefenseSweat and Oil on your skin kill most Pathogens they come in

contact with due to the fact that your Sweat is acidic.

Mucus Membranes

Thick walls of Mucus line your Nose, Throat , and Stomach. Mucus acts as a kind of glue that traps any Pathogens that happen to be going by . The Cilia (little hairs) then move the Pathogen filled

Mucus out of the body

SecretionMucusTearsSalivaSweat

The various secretions push out pathogens and also

contains a chemical called Lysozyme that breaks

through the cell walls of Bacteria therefore killing

them.

Mucus

Tears

Saliva

Sweat

Second line of

Defense

Innate Immune Response

There are four important non-specific (Innate) defenses that come into action once a pathogen has entered the body.Inflammatory ResponseTemperature ResponseProteinsWhite Blood Cells

The Inflammatory Response

A series of events that repress infection and speed healing through dilation of blood vessels.

Histamines dilate blood vessels and bring white

blood cells to the area of infection thus causing

Inflammation

Swelling ,Redness, and Puss may also occur

(Puss—A build up of millions of dead white blood cells )

Temperature Response

To fight pathogens the body will raise its temperature a couple

degrees above normal to try and kill them.

Fever helps to combat bacteria due to the fact that Pathogens

cannot survive high temperatures.

ProteinsA variety of proteins

provide a non-specific defense from Pathogens

Interferon is a protein release by cells infected with a virus.(Its causes nearby cells to create an enzyme that prevents Viruses from

making proteins and RNA)

White Blood Cells (Phagocytes)

Neutrophils , macrophages and natural killer cells wait within

tissue for pathogens to annihilate.

Neutrophils overwhelm and destroy pathogens by sacrificing themselves for wellbeing of the

rest of the body

Macrophages consume and kill pathogens as well as

clear the body of dead cells and debris.

Natural killer cells puncture the cell membranes of

pathogens, allowing liquid to rush in and make the cell

burst

The Third Line of

Defense

The 3rd line of defense is Called “The Acquired Immune Response” is a specific

Immune response unlike the first and second line of defense. Its is an Immune response that you gain by being infected with pathogens or virus’ and combating

them.

Acquired Immune Response

Helper T-Cells activate both cytotoxic T cells and

B cells

Helper T-Cell

The helper T Cells recognize Virus’s that

would otherwise go un-noticed. It then alerts the

B-Cells. The B cells first analyze the virus then

they construct a antibody that is specifically for that

one virus.

After the Virus is smothered in antibodies and cannot

infect anything other cells the killer t cells are called to the seen to dispose of the incapacitated virus and kill

the infected cells.

Armed Memory B-Cell

Antibodies are Immune System proteins that destroy pathogens

The End!!!

By:Johnathan Baekgaard