• Pathogens- Foreign invaders that enter the
immune system and cause an immune
response.
• Also known as Antigens
– Bacteria
– Viruses
– Fungi
– Protists
Streptococcus
Bacteria
Rhinovirus
Amoebic
Dysentery

• Pathogens have tags surrounding them called
that indicate that they are invaders
to the body
Bacteria
Antigens

• Antigen - any substance that the body regards as foreign (virus,
bacterium, toxin)
• Antibody - a disease fighting protein developed by the body in
response to the presence of an antigen
• Antigen-antibody reaction or immune reaction

– Phagocytes (macrophage )-
phagocytic (surrounds and
engulfs) protects body by
ingesting invading cells
– Lymphocytes – Cells that
produce specific antibodies
against a foreign pathogen
•Leukocytes- Another name for
white blood cells, there are two
general classes of leukocytes

– mature in thymus gland
– Cell mediated immunity
– mature in bone marrow
– antibody-mediated immunity

• Any change other than injury that disrupts the
normal functioning of the body. Some
diseases are inherited, some are caused by
environmental factors, and other are caused
by agents such as bacteria, viruses, parasites
and fungi.

• The human body provides the right conditions
for pathogens. We provide them with the
right temperature, watery environment
nutrients

• Skin
– Barrier
– Provides and acidic environment

All contain Lysozymes which destroy
bacteria and viruses

• The Immune System- bodies primary defense
against pathogens
• Pathogens are disease causing microbes

What do you think happens to the number of white blood cells in
the area?

27

28

An autoimmune reaction attacks the
insulin producing cells of the pancreas