Transcript Immune System

Immune System
Keeping you safe
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Good health is something you may take
for granted.
Until you or someone close to you gets
sick.
Then the value of good health becomes
all too obvious
Why do you get sick?
How do you get better?
These are questions that can be
answered!
Disease
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Disease: any change other than an
injury that disrupts the normal
functions of the body
• Some are inherited
• Some are caused by the environment
• Some are caused by bacteria, viruses,
and fungi
Pathogens
Pathogens: disease causing agentssuch as- bacteria, virus, and fungi
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Patho- sickness agent
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Gen- to create
 Infectious diseases- diseases caused
by pathogens infecting the body
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Germ Theory of Disease
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I.
• History of disease origin belief
curses
 evil spirits
 night vapors
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Dispel History of Disease Origin
Beliefs
 Louis Pasteur
 Robert Koch
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Koch’s Postulates
Observations of both Koch and
Pasture was that:
 Disease is caused by microorganisms
(germs)
 Led to the Germ Theory of Disease
 World filled with microorganisms
 Which microorganism actually causes
the disease?
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Here’s the scenario:
 1975 Allen Steere at
Yale University:
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Answered the question- which
microorganism causes a specific disease!
Small area of Connecticut- 39 children,
several adults suffered from joint pain and
inflammation.
Most cases in summer/ fall
Suspected could be pathogen carried by
an insect.
Many children reported infection began
with what they thought was an insect bite!
Bite followed by expanding rash
Bull’s Eye
Rash
Lyme Disease
Steere called it Lyme Disease
 Linked skin rash to tiny deer tick
 Dr. Willy Burgdorfer
• found spiral shaped bacterium in the
ticks (got to name the bacteria
Borrelia burgedorferi)
• found same spiral shaped bacterium
in the patients
Borrellia bergdorfori
• injected bacteria into lab mice
• mice got arthritis and other
symptoms like the children
• Steere recovered the bacteria from
mice- passed on those bacteria to
healthy mice
• Healthy mice then got sick
Koch’s Postulates
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Burgdorfer and Steere relied on Koch’s
(Pronounced Cock’s) Postulates
Robert Koch Developed series of guidelines still
used today to identify pathogens that cause a
specific disease
• 1) Pathogen should be found in sick organism and not
that of a healthy one
• 2) Pathogen must be isolated and grown in lab in pure
culture
• 3) When purified pathogens placed in a new host, new
host get same disease that infected original host
• 4) Injected pathogen should be reisolated from the
second host, should be identical to the original pathogen
Pathogens
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Agents of Disease:
Why is the human body so good for
pathogens?
right temperature
moist environment
abundance of nutrients
Large Intestines: harbors dense colonies of
bacteria
Mouth, throat, tissues surrounding eyeballs:
bacteria and yeast
Vaginal area: lots of yeast-how do we get yeast infections?
Antibiotics
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Antibiotics kill off the normal bacteria that
keep yeast in check, with free reign of the
area, yeast go to work and over produce
causing a curd like substance to be
produced, a.k.a.- yeast infection.
Question? How do pathogens cause
disease?
bacteria can break down the tissues
• parasites include protists, fungi and worms
• some remove nutrients from digestive system
• others destroy blood cells and neurons
bacteria can release toxins in the
body
 toxins: poisons that produce illness
by disrupting bodily functions
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Botulism – C. botulinum
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Tetanus- C. tetani
found in soil
 one of most powerful toxins/ does not allow
muscles to go back to relaxed state.
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Anthrax
Spread of Disease
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How Diseases are Spread:
Some infectious disease can be spread
from person to person through:
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Coughing
Sneezing
Physical Contact
Contaminated water
Food
Infected animals
Vectors
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Vectors: animals, such as ticks and mosquitoes,
spread many diseases
Vector: organisms that carry disease-causing
agents
What was the vector for Lyme disease?
Often the key to stopping disease from spreading
Avoid tall grass will keep the deer tick away
Wash Hands
Good Hygiene
Avoid infected people
STI’s (STD’s)
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Sexually Transmitted Infections
(STI’s)
diseases by exchange of bodily fluids
 also known as having sex
 some of the most dangerous pathogens are
spread by having SEX
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STI’s (STD’s)
Syphilis- caused by bacteria in body
fluids
 Gonorrhea- caused by bacteria in
body fluids
 Chlamydia- caused by bacteria
 Hepatitis B&C- caused by virus
 AIDS- caused by virus
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STI’s (STD’s)
Genital Herpes- caused by virus
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Fighting Infectious Diseases:
 If prevention fails (keeping pants
on!) there are drugs that can
possibly help to fight pathogens.
 Most useful drugs- antibiotics
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Antibiotics: compounds that kill
bacteria without harming the cells of
animals or humans by interfering
with the cellular processes of
microorganisms
 Antiviral Drugs: inhibit ability of
viruses to invade cells and multiply
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Drugs
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2 methods:
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destroy cell wall of bacteria, so cannot live
(penicillin)
• Fleming tried to grow Staphylococcus (a
bacterium), became contaminated with
Penicillium notatum. Fungus inhibited the growth
of the bacterium.
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Blocks protein synthesis in the ribosome of
bacteria (streptomycin)
• Antibiotics have NO effect on Virus
Immune System
II.
 With all the pathogens scurrying
about, why aren’t we always ill?
 We have a protective system known
as the Immune System: a series of
defenses that guard against disease.
 some are simple barriers
 others are pistol packing security
guards
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Non-Specific Defenses
The Simple Barriers
 1st line of defense:
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• keep pathogens (the bad guys) out
• Skin is crucial, the most important
barrier!
Non-Specific Defenses
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When blood shed begins (skin torn apart)
pathogen allowed to enter and infect
Shows the pinnacle importance of skin
We’d be hopeless with out the skin
Mouth and Nose:
Mucous- traps virus and bacteria
Cilia- the gatekeeper pushes pathogens
away from lungs
Stomach acid and digestive enzymes:
Non-Specific Defenses
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Full on blitz, sneak past mucous and the
gatekeeper (cilia) and reach stomach
Destroy pathogens
Lysozymes: enzymes that break down
bacteria cell walls
• Found in mucous, saliva, sweat and tears
• 2nd line of defense:
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(first line fail) Inflammatory response is
next in line
Inflammatory response
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Inflammatory response: a non-specific defense
reaction to tissue damage caused by injury or
infection!
Steps:
Pathogen infects tissues
Blood vessels dilate (expand)
White blood cells (leukocytes) leak from dilated
vessels and go to infected areas
WBC are phagocytes: engulf and destroy bacteria
Phago= to eat
Cyte= cell
Inflammatory response
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Hypothalamus: releases
endogeneous pyrogenes (chemicals)
that increase core body temperature
• This is a fever!
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Higher temperature slows down or
stops growth of pathogens
Inflammatory response
Higher temperature from fever
increases heart rate so that WBC get
there faster
 Higher temperature speeds the
activity of WBC’s and the reactions
that help repair damaged tissues
 Interferons- help resist viral
infections
 inhibit the synthesis of viral proteins
therefore blocking viral replication
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Specific Defenses:
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Non-specific failure! Immune response
becomes specific and varied- known as
the IMMUNE RESPONSE
Triggered by Antigens: carbohydrates,
proteins, or lipids on a pathogen that
trigger the immune response
Immune response can be humoral
immunity or cell- mediated immunity
Specific Defenses:
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Humoral- immunity against pathogens in
body fluids (blood and lymph)
Produced by lymphocytes
• B- lymphocytes produce antibodies
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Antibody: protein that helps destroy a
pathogen
• Generally “Y” shaped
• Two identical antigen binding sites that bind to
antigen
Specific Defenses:
Influenza Virus: Here comes trouble
with a capital “I” (do antibiotics
help?)
 Influenza enters- has antigen on
surface
 Antibody recognize virus as foreign
 Begin to clump on (pile on top)
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Specific Defenses:
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Phagocytes recognize clump (gobble
gobble) engulf and destroy mass!
How are antibodies produced?
Custom-made- specific to a specific
antigen!
B-cells (B= bone marrow) made early in
fetus development:
Genes coding for antibodies rearrange
slightly differently in each B-cell
Specific Defenses:
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At end of development, due to slight
difference, there are millions of different
B-cells, each of which can recognize a
different antigen
So, when pathogen enters the body, a
small fraction of B-cells will recognize as
foreign.
B-cells very happy and reproduce (split)
many copies made, known as plasma
cells.
Specific Defenses:
Plasma cells release the antibodies
into blood stream to seek out and
destroy the pathogen.
 Plasma cell activation and regulation
monitored by T-lymphocytes (T=
thymus)
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Specific Defenses:
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Cell Mediated Immune Response:
Helper T regulate production of antibodies
by B-cells, but other T cells can attack
pathogens directly- called Killer T cells
(cytotoxic T cells)
Killer T’s transfer proteins into membrane
that cause it to be “leaky” so fluid will leak
out of the cell. Pathogen dies!
Killer T- why tough to do organ transplant:
Specific Defenses:
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We will recognize our own organs by
surface proteins
Everybody has different surface proteins
that will be recognized as foreign, immune
system will attack!
Rejection is painful even at the organ
level! (That’s why people resort to toilets)
Must find very similar surface markers and
take drugs to suppress immune response
to prevent rejection
Permanent Immunity
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Been known for more than 2000 years
(measles/small pox- got once, never
again)
Known as permanent immunity- done by
memory B and T cells that are ready and
armed
Active Immunity
Edward Jenner: produced first vaccine
Permanent Immunity
Cowpox sufferers never got small
pox?
 Could you infect someone with
cowpox to prevent small pox?
 Decided to infect Jamie Phipps with
fluid from cowpox sores.
 Jamie got cowpox.
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Permanent Immunity
Two months later, the mad scientist
Jenner took it one step further,
infected Jamie with small pox.
 Surprise! Jamie did not die a
horrible death from small pox!
 The first vaccine discovered.
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Vaccination
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Vaccination: injection of a weakened or
mild form of a pathogen to produce
immunity (vacca means cow- from cowpox
and cow hands and milk maids and
farmers and other people who deal with
cows that gave Jenner the brilliant idea to
play with little Jamie)
Immunity from a vaccine is known as
ACTIVE immunity because body of
recipient has the ability to respond
immediately to exposure to the pathogen.
Passive Immunity:
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If antibodies from another animal for a
particular pathogen are injected into our
bodies- the antibodies produce a passive
immunity (only a few weeks) while they
are in the body.
Often given to travelers (who will be in
tropical areas for a limited time)
Maternal immunity is a passive immunity
(placenta/ milk provide antibodies)
III. Immune System Disorders
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Although the immune system
defends the body against all the evil
powers of the world, sometimes
disorders occur.
Immune System Disorders
Two Main Types of Disorders:
 Immune system over reacts to
antigens (the “girl response”) –
produces discomfort or even disease
 Immune system is weak (the “boy
response”)
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Immune System Disorders
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Allergies (overreaction)
Result when antigens from allergens
(things that create allergies, such as
pollen, or another girl in the picture, or
dust mites) bind to mast cells (another
type of immune cell in the nasal passage)
Allergen antigen bind to mast cell, mast
cell release chemicals known as
histamines that increase blood and fluid
flow to area
Immune System Disorders
Histamines responsible for sneezing
and runny nose and eyes
 Antihistamines for allergies?
 Can result in asthma- smooth muscle
contractions reduce size of
passageway of air in lungsbreathing difficult- usually triggered
by particular antigen (i.e. pollen)
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Autoimmune Diseases
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Immune attacks own body- yup, you guessed it,
an autoimmune disease!
Could be caused by an infection
Example: strep throat (streptococcus bacteria) if
left untreated will cause the immune system to
produce antibodies to destroy the bacteria.
Antigens on streptococcus so similar to cardiac
cells, immune response could also attack heart
Results in rheumatic fever: antibodies and killer T
cells kill and scar cells of the heart lining
(pericardium) and valves
Autoimmune Diseases
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Example:
• Juvenile onset diabetes
• Multiple Sclerosis
• AIDS
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Example of cells of immune system
weakened by infection
Autoimmune Diseases
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Early 1980’sPeople started coming down with infections
including:
Protozoans in the lungs
Fungal infections of the mouth and throat
Karposi Sarcoma (a rare skin cancer)
Normal immune systems could battle these
infections off like the weak advances Iraqis
Doctors soon realized that their patients’ immune
systems must be compromised.
HIV / AIDS
Way the disease was spread made
them suspect a virus.
 1983- HIV identified (Human
Immunodeficiency Virus)
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HIV / AIDS
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The nuts and bolts:
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Virus enters body (HIV)
Attaches to receptors on T cells
T cells normally help recognize and aid immune
response
Body does not produce antibodies to HIV
HIV replicates within cells of immune system
(because it is inside cells, less likely to bind to
antibodies)
NO CURE FOR AIDS
Spread by contact with infected blood or other body
fluids (Oral/Anal still going to get it)
Abstain
Faithful, get checked, latex condom