The Immune System

1
The Immune System
2
Pathogens include certain bacteria, protists,
fungi, and worms, and viruses. Diseases that are
caused by pathogens are known as infectious
diseases
3
This system destroys pathogens or invaders of
your body in different ways
4
Non Specific Defenses (works with many invaders)
include Skin, sweat and oil glands, saliva,
tears, mucus, cilia and stomach acids and enzymes.
Macrophages and neutrophils are able to detect
invaders and actually engulf them (phagocytosis)
Pus is a mixture of dead neutrophils, broken down
tissue cells and dead pathogens.
5
Natural Killer Cells can release chemicals that
make holes in a cancer cell or a cell infected by
a virus. Other parts of the immune system
enhance their action.
6
At the site of an invasion Mast cells release
histamine that causes the blood vessels to dilate
bringing more blood and phagocytes (macrophages,
neutrophils) to the area.
7
Interferons are sometimes produced from virus
infected cells. These interferons then migrate
to uninfected cells and trigger the production of
proteins that will inhibit the virus to
successfully reproduce in those cells.
8
Lymphocytes originate in bone marrow from stem
cells, which also give rise to various other
kinds of cells. Some lymphocytes, called B cells
or B lymphocytes, continue their development in
bone marrow. Others, called T cells or T
lymphocytes, are transported to the thymus gland
where they mature. Eventually both B and T cells
travel in the blood to the lymph nodes and other
parts of the lymphatic system.
9
The surfaces of viruses, bacteria, fungi, cancer
cells, pollen, and other cells contain certain
molecules called antigens. An antigen is a large
molecule, usually a protein, that provokes an
immune response. The word antigen is a
contraction meaning "antibody-generating."
Antibodies are proteins found on the surface of
certain white blood cells, or in blood plasma,
that attach to particular antigens.
10
Once B Cells have recognized their antigen,
they are activated, divide then develop into
plasma cells that secrete the specific antibody
that corresponds to the antigen. The antibodies
immobilize the invader and target them for other
cells to attack them. You have more than 100
million different B Cells that are waiting to
someday find their antigen. This all happens in
body fluids and the blood or humoral immunity.
11
Cell Mediated Immunity and the role of the helper
T Cells with cytotoxic T Cells and humoral
immunity.
Macrophages display the antigens of pathogens
they have "eaten." This display activates a
specific version of helper T cells. The activated
helper T cells in turn stimulate cytotoxic T
cells and B cells. When a Cytotoxic T Cells find
their antigen, they clone themselves.
12
When you are first exposed to a pathogen,
specific B and T cells multiply and defend
against that particular pathogen. Some of that
"brand" of B and T cells remain in your body.
These long-lasting lymphocytes are called memory
cells. The first formation of B and T cells to
battle a new invading pathogen is called the
primary immune response. This first response is
relatively slow and weak because time is needed
for enough specific lymphocytes to form to defeat
the pathogen.