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Immune system
Pathogen=
Disease causing agent
► Any
change (not including injury) that
disrupts the normal
functions of the body
► Caused by
 Agents►bacteria,viruses,fungi
 Materials in the
environment
►(cigarette
smoke
 Inherited- hemophilia
Germ Theory
► Louis
Pasteur/Robert Kouh-1800 said disease
caused by germs…what about before?
► What rules do we follow for identifying the
microorganism that causes a specific disease.
 Koch’s Potulates
► Pathogen
identified in sick organism not healthy one
► Pathogen grown in pure culture
► Healthy organism becomes sick when infected with pure
culture pathogen
► Pathogen extracted and must be same as original
pathogen
Agents of Disease
► Our
body is great for pathogens
 Suitable temperature,watery,lots of nutrients
► We
already have loads of yeast and bacteria in/on us- large
intestine, mouth which are either harmless or helpful
 What do the pathogens do?
► destroy cells,release toxins, block bloodflow,remove
nutrients,disrupt bodily functions
►
► Virusis
 Invade and replicate on the cells using the cells
own RNA or DNA (that’s why we cant kill a virusis)
Bacteria-Most are harmless
Harmfull cause disease in two ways
1.breaking down tissue of the
2.infected organism or releasing
toxins
Protists ex Malaria, Sleeping sickness
feed off the nutrients of infected host
Worms- same as protists
Fungi- Most harmless- ringworm etc can be
deadly
How are Diseases spread?
► Physical
contact
 To help cover your mouth, wash your hands
► Contaminated
Food and Water
 All food contains bacteria
► Infected
Animals
 The animals that carry the pathogen from
person to person are called =vectors
How do we fight them?
► Antibiotics-
kills the bacteria not the cells
► Over the counter drugs (careful) these treat
the symptoms not eh disease.
40.2 Immune system
► Immune
systems function is to fight infection
through the production of cells that inactivate
foreign substances or cells. This is immunity.
 1st line of defense is your skin, mucus, sweat, tears
contain lycoenzyme and salt. Oil and sweat glands
produce acidic environment.
 Mouth nose and anus are protected by mucus, cilia that
line your nose and throat help push pathogens away
from your lungs (Lugie) stomach has acid.
Second line of defense
► Inflammatory
response
 Mast cells release histamines that cause the blood walls
to be leaky. White blood cells then cross over into the
tissue. Many are phagocytes that engulf and destroy
bacteria. Tissue swells you say ouch!
 Immune can release chemicals that increases (yep, you
make the temp) =Fever . High temp stops or slows the
growth of many pathogens (Bacteria can replicate every
20 minutes)
 For viruses we make proteins called interferon
Specific Defenses= immune
response
► Antigen
= substance that triggers a response Two
types
► Humoral immunity made of B cells (lymphocytes)
they provide immunity against antigens and
pathogens in body fluids)
► Pathogen enters the body and its antigens are
recognized by Bcells which grow and divide
rapidly, producing large numbers of plasma and
memory B cells. (memory B cells stay behind after
pathogen is gone so you will not be reinfected
Cell mediated Immunity
►T
cells defend against abnormal cells and
pathogens inside living cells. (both are
lymphocytes)
 They do this by T cells dividing into Killer T cells, helper
T cells, suppressor Y cells and memory B cells.
 T cells kill invador
 Helper T produce memory T cause secoundary response
if pathogen ever comes back
 When attack is under control suppreassor T cells shut
down Killer T
 Problems Transplants
► Acquired
immunity is when we deliberately
infect a person either by exposure or a
Vaccination
► Passive immunity- limited time ex- Moms
milk, rabies shot, Malaria medication etc…