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The Immune System
Basics
Pathogens of Disease
• Bacteria
– Bacteria are cellular (prokaryotic) and are
Living organisms
- 3 common shapes
• Bacilli (rod), cocci (circular), spirilli (spiral)
– Cause disease by
• Destroying cells and tissue
• Releasing toxins in body
– Examples
• Strep Throat, tetanus, anthrax, syphilis, tuberculosis, MRSA, food
poisoning, chlamidia, gonorhhea
– Preventions
• Some have vaccines, personal hygiene, antiseptics
– Treatments
• Antibiotics- substances that can be administered that kill the
bacterial cells causing infection
– Usually break down cell walls or interfere with metabolic
processes
Pathogens of Disease
• Viruses
– Noncellular particles
• Genetic material (DNA or RNA)
• Capsid-protective coating made of protein
– Not considered living
• Cannot reproduce on own, no metabolic processes, no response to
stimulus
– Cause disease by
• Disrupting cellular activity and destroying cells
– Examples
• Common Cold, Flu, Small Pox, HIV, chicken pox, genital warts, herpes, hepatitis
– Prevention
• Some have vaccines, personal hygiene, antiseptics
– Treatments
• None- body must defeat on own, some the body cannot defeat EVER
• Some drugs (antiviral) can slow the spread of virus within the body
Function of the Immune System
to fight infections and protect the body from
invaders.
White Blood Cells-Specialized cells of the
immune system
fight disease
Pathogens
• Bacteria (food poisoning, tuberculosis,
pneumonia)
• Viruses (influenza, AIDS, colds,ect..)
• Protists (malaria and others)
Infect body and cause disease!
Antigen- a substance on the surface of a pathogen
that triggers an immune response (DEFENSE).
Nonspecific Defenses
• Skin- Creates barrier between external
environment where pathogens exist and the
inside of the body
– Pathogens must enter body to cause
infection/sickness
• Inflammatory Response (Swelling)-Blood
vessels expand and WHITE BLOOD CELLS
(disease fighters) enter the wound or infection
site
• Fever- Body raises core temp. to try to kill
pathogen
– Some pathogens can only survive under certain temp.
Specific Defenses
• Humoral Response
– Involve Special Types of White Blood Cells
• T-Helper Cells activate B-Cells when they detect invaders
(pathogens)
B- Cells (B lymphocytes) produce plasma cells
Plasma cells produce antibodies
– antibodies=substance that will cling to the antigen on the
surface of a pathogen an immobilize the pathogen or cause
them to cling together.
– Once infection detected by helper T many plasma cells are
generated B cells to produce antibodies
• Macrophages (PHAGOCYTES)-engulf and destroy
immobilized or inactivated pathogens
Specific Defenses
• Cell Mediated
– Helper T Cells- recognize pathogens and
activate B cells (Humoral Response) and
Cytotoxic (Killer) T Cells
– Killer T Cells- Once activated kill pathogen
directly
Immunity
• Bodies ability to not become sick against a
specific invader/pathogen
– It takes a while for plasma cells to figure out what
antibody will kill a specific pathogen, many antibodies
are produce in “trial and error method”
– Pathogen causes infection and sickness in meantime
– Eventually plasma cells produce an antibody that
works.
– Special B memory cells remember the correct
antibody that worked against that specific invader
– The next time the invader enters your body the
Immune system knows how to destroy it before it can
cause infection or disease.
Vaccine
• Altered (weakened) form of the real pathogen
Scientists alter in lab
– No longer capable of causing disease
– Injected in body
– Allows body to recognize and immune system build
immunity to the pathogen
• When the real pathogen enters body your body
is already immune (knows how to kill it before it
can cause infection/sickness)
Treatments for Diseases
• Bacterial Diseases- bacteria are living
things
– Antibiotics-drugs that interfere with the
chemical processes of living things
• Specifically harm bacterial cells without causing
harm to us
• Viral Diseases-not living
– Body must defeat on own, no cures
A.I.D.S and the Body
• AIDS infects and kills Helper T Cells
• Helper T Cells detect pathogens/invaders
• Once enough T Helper are killed by virus the
body is no longer capable of recognizing
invaders
• RESULT- Person becomes seriously infected or
sick from pathogens that a healthy person may
defeat rather easily
– Usually die from simple infections
(cold,flu,pneumonia)