Transcript The Immune System

The Immune System
History of Medicine
1857
1883
Germ Theory
Louis Pasteur
hypothesizes that
disease is caused by
small organisms.
1928
1955
Today
History of Medicine
Koch’s Postulates
Robert Koch finds 4
conditions that prove a
pathogen causes a disease.
1857
1883
Germ Theory
Louis Pasteur
hypothesizes that
disease is caused by
small organisms.
1928
1955
Today
History of Medicine
Koch’s Postulates
Robert Koch finds 4
conditions that prove a
pathogen causes a disease.
1857
1883
1928
1955
Germ Theory
Antibiotics
Louis Pasteur
hypothesizes that
disease is caused by
small organisms.
Sir Alexander Fleming
discovers penicillin.
Today
Bacteria don’t grow around mold!!!
History of Medicine
Koch’s Postulates
Robert Koch finds 4
conditions that prove a
pathogen causes a disease.
1857
1883
Polio Vaccine
Jonas Salk’s vaccine against polio becomes
available. Discontinued in the U.S. in 1994.
1928
1955
Today
Polio Comeback!
Germ Theory
Antibiotics
Louis Pasteur
hypothesizes that
disease is caused by
small organisms.
Sir Alexander Fleming
discovers penicillin.
Worldwide efforts
increase to vaccinate
people against polio.
Pathogens
• Defined: microorganisms
that cause disease
– Viruses: turn cells into
virus making factories
– Bacteria: prokaryotes
that can release toxic
chemicals
– Fungi: pierce cells and
absorb the nutrients
– Protozoans: single cells
protista (eukaryotes)
– Parasites: grow and feed
on a host
Pathogens (contd)
• Some carried by wind,
water, direct contact,
indirect contact…
• Some carried by vectors
– Vector: object that
carries a pathogen
– Examples:
1) Malaria – mosquitos
carry the protozoan
2) Black Death – carried by
flea’s of mice
3) West Nile Virus – carried
by birds, but spread by
mosquitoes
The Skin
• 1st line of defense: physical barrier
• Oils & sweat destroy some pathogens
– Some cells burst
– Some cells shrivel
Mucus Membranes
• Coat the openings of the body
– Nose, mouth, ears, eyes, genitals, anus
• Lined with cilia & sticky fluids to trap pathogens
White Blood Cells
• Job: Search & destroy
• Phagocytes: surround & engulf invaders
– Phagocytosis (see animation)
• Lymphocytes:
– T cells: destroy infected body cells
– B cells: Inactivate invaders
Defense Proteins
• Antibodies
– Proteins made by B cells
– Attach to antigens found on
surface of cells
– How they help:
1) Bind to antigens of
pathogen (like handcuffs)
– Causes pathogens to clump
– Easy targets for phagocytes
2) Weakens the cell membrane
of pathogen
– Causes them to burst
Defense Proteins
• Interferon
– Cell becomes
infected by virus
– Infected cell
releases
interferon to
neighbors
– Healthy cell
(right) absorbs
the interferon
and creates
defense enzymes
– Healthy cell able
to fight virus
virus
Virus
RNA
New virus
New virus
New virus
New virus
Interferon
proteins
New virus
Vaccination
• Prevents infections (not a
cure)
• Vaccination process
– Weakened pathogen is
injected
– Antigens of pathogen
cause your immune
system to attack
• Immune system response:
– Production of memory
cells (for future
infections)
– Antibodies bind to
antigens (for current
infection)
• Goal: Speed up immune
response if you encounter
the actual virus
Kobe Kuiz
1) What did Louis Pasteur contribute to our knowledge of medicine?
2) Which part of our immune system coats the openings of the
body?
3) Name and describe the two types of lymphocytes.
4) What are antibodies and how do they help keep us from harm?
5) Summarize how vaccines are created.
6) Which pathogen…
1)
2)
absorbs nutrients from living tissue?
is prokaryotic?
7) Which illness is spread by mice?
8) What is the vector of malaria?