Transcript File

The Immune System
Health and Disease
Disease
is an abnormal condition that affects the body of an organism.
 Germ Theory of Disease: Observations of Louis Pasteur and Robert Koch led
them to believe that infectious diseases were caused by microorganisms of
different types (germs).

Science that deals with protecting and improving the health
of the people in a community
• Focuses on the health of the whole population
• Ways to improve public health:
•

Education about diseases and causes

Provide clean drinking water

Promote healthy living habits

Ex. Farmers markets and hand sanitizers
in schools and hospitals

Research causes and treatments of
various diseases

Vaccination Campaigns

Food and Drug Safety regulations
Types of Diseases
Infectious Disease



Spread from one organism
to another
Measles and the common
cold
Pathogens

Organisms and agents that
cause infectious diseases

Certain bacteria, fungi,
protists, and viruses
Noninfectious Disease



Does NOT spread from one
organism to another
Cancer, diabetes, allergies, heart
disease, and most mental
illnesses
Causes can include:



environmental factors such as
chemicals and radiation,
individual’s genes,
behavior such as smoking, poor
eating habits, lack of physical
activity, etc.
• Spread from one organism to another
• Agents of Disease:
 Bacteria: living, break down the tissues of an infected
organism for food, or release toxins that interfere with
normal activity in the host
 Streptococcus, anthrax, pneumonia, lime disease
 Virus: nonliving, replicate by inserting their genetic material
into a host cell and taking over many of the host cell’s
function.
 Common cold, influenza, chicken pox, rabies
 Fungi: cause infections on the surface of the skin, mouth,
throat, fingernails, and toenails
 Ringworm, thrush
 Protists: single-celled eukaryotes may infect people through
contaminated water and insect bites
 Malaria, African sleeping sickness
 Parasites: worm-like (that infect humans), may enter
through mouth, nose, skin, etc.
 Trichinosis, hookworm
• NOT spread from one organism to another
•
Genetic
•
•
passed down from one generation to another to its offspring
Not always “ALL-OR-NOTHING”
•
You may get the gene but outside factors can influence the expression of disease
Ex: Gene for heart disease influenced by diet and exercise
• Mutations
• changes to an organism’s DNA
• Changes in an organisms DNA
• A mutation is passed down to every cell that develops from that mutated cell
•
If a REPRODUCTIVE CELL or GAMETE mutates mutation can be passed from
parent to offspring
•
If SOMATIC or NORMAL cell mutates mutation CANNOT be passed to offspring
• Environmental factors
• Radiation
• Toxins/chemicals
• Natural (plants animals and fungi)
• Unnatural (pollution)
• Air Pollution
•Respiratory disease (asthma) and lung cancer
• Water and Soil Pollution
• Heavy metals taken in by plants and eaten by us
• Heavy metals runoff into lakes and rivers and get into our water supply
• Poor habits
• Drugs
• Alcohol
• Tobacco
Bacteria and disease




Reproduce rapidly
Spread easily
Break down cells in the host’s
body for food=tissue damage
Release toxins into hosts’ body


Toxin- a poison that acts on a
particular body system
 Ex. Bacteria that causes strep
throat releases toxin that can
cause scarlet fever
 Tetnus-disease caused by
bacteria that also release toxin
that affects nervous system
Diseases caused by bacteria




Strep throat
Pneumonia
Anthrax
Lyme disease
Viral Infections
•
What is a Virus?

•
•
Diseases caused by a virus:

Common cold or influenza (flu)

Rabies

Small pox

AIDS (Autoimmune deficiency syndrome)
Viruses can only replicate or make more viruses
when they are in a living cell (the HOST)

•
Tiny particles of genetic info (RNA or DNA)
surrounded by a protein coat
They must HIJACK the cells machinery (Organelles)
Most Viruses attack only one kind of organism

Example: bacteriophage is a virus that only attacks
bacteria (phage means “to eat”)
How a Virus Infects A Cell
•
•
•
•
•
•
Virus attaches to bacterial cell wall
injects DNA into bacterial cell
Virus directs cell to make viral nucleic
acid
Virus DNA and proteins assemble into
new virus
Bacterial cell opens and the virus
particle is released
Virus that infects bacteria is called a
BACTERIOPHAGE
Making it simple!
Start 2:30
End: 6:20
Lytic Cycle
Lysogenic Cycle
3 ways To Prevent Infectious Disease
1.
2.
3.
Vaccinations
Practice Good Hygiene
Avoid people you know are sick
Vaccines
•
•
Weakened OR deactivated forms of
pathogen that are introduced into your
body to cause YOUR immune system to
produce antibodies that fight off the
pathogen
Many different vaccines have been made to protect
people from viruses and bacteria
•4 Ways Vaccines Work
1)
Click Here! How Vaccines
Work VIDEO
Weaken the Virus
•
viruses are weakened so that they reproduce themselves very poorly once inside the body
•
Body is able to make “memory B cells” to protect patient against the virus for life
+ only one or two doses need for life long immunity
- may cause a mild version of disease and people with weakened immune systems (cancer or AIDS) cannot get
them
2)
Inactivate the Virus
Viruses are completely inactivated (or killed) with a chemical
the virus is still "seen" by the body and cells of the immune system that protect against disease are
generated
+ anybody can get this vaccine
- Many doses are required
•
•
3)
Use Part of the Virus
just one part of the virus is removed and used as a vaccine (proteins on the surface of the virus)
can be used when an immune response to one part of the virus (or bacteria) is responsible for protection
against disease
+ a few doses= long lived immunity
•
•
4)
Use Part of the Bacteria
Make vaccine by inactivating toxin with a chemical (the toxin, once inactivated, is called a toxoid).
•
Toxoid no longer causes harm and body create immune cells against this specific toxin
•
Make vaccine using the sugar coat of specific bacteria
•
Body build immunity against bacteria with that specific sugar coat
- requires many doses to build immunity
•
Protects the body from
disease
• specialized cells and
organs that work together
to protect you from
pathogens
Barriers that keep pathogens out of
the body
• The Skin
• largest organ in the body, provides a protective barrier between you and the outside
environment.
• Mucous membranes
• line nasal and respiratory organs
• air you inhale may contain pathogens
• become trapped in mucus, fluid secreted by mucous membranes
• then moved by cilia to opening to be blown out or swallowed, where stomach acids take
care of them
• Stomach acids, sweat, and tears are all barriers to block out pathogens.
Inflammatory response to
tissue damage
• If you cut your finger, Inflammatory responses begins as soon as pathogens enter the body:
1. Blood vessels near the cut expand
2. Plasma fills the spaces between cells, carrying white blood cells to injury
(macrophages-WBC that engulf and destroy pathogens), and platelets seal the cut
3. Area surrounding cut may become red, swollen, and inflamed? Why?
4. Another sign: fever
• raises your body temperature to help fight infection by making your body less
suitable for the growth of harmful bacteria
• macrophages also work better at higher temperatures
First Line and Second line of Defenses: NONSPECIFIC
DEFENSE
Immune response attacks specific
pathogens using specialized cells and
proteins
• Specific Defense
 Macrophages and other specialized white blood cells called T
cells and B cells
 T Cells- white blood cells that attack and kill harmful
cells
 B-cells- white blood cells that make antibodies.
 Antibody- Y-shaped protein that attaches to a specific foreign
substance= antigen= found on the surfaces of bacteria and
viruses.
 lock and key model= antibody and antigen
 causes the antigen to clump together and become
harmless
 clumped antigens are then engulfed by macrophages or
destroyed by T cells
The granulocytes often take the first stand during an infection. They
attack any invaders in large numbers, and "eat" until they die. The pus
in an infected wound consists chiefly of dead granulocytes. A small
part of the granulocyte community is specialized in attacking larger
parasites such as worms.
The macrophages ("big eaters") are slower to respond to invaders than
the granulocytes, but they are larger, live longer, and have far greater
capacities. Macrophages also play a key part in alerting the rest of the
immune system of invaders. Macrophages start out as white blood cells
called monocytes. Monocytes that leave the blood stream turn into
macrophages.
The dendritic cells are "eater" cells and devour intruders, like the
granulocytes and the macrophages. And like the macrophages, the
dendritic cells help with the activation of the rest of the immune
system. They are also capable of filtering body fluids to clear them of
foreign organisms and particles.
Results from exposure to specific pathogen
• Weakened or deactivated
form of a disease-causing
agent
• When introduced, it
activated immune system to
make antibodies to the
pathogen
Created by transferring antibodies made from one organism into
another organism
1. Person bitten by a dog or bat
2. Often acquired before birth
may be given antibodies taken
from people who have been
• As the fetus develops, it receives
vaccinated against rabies.
antibodies from its mother
Why?
Rabies can progress faster than
an infected person can produce
antibodies
• Newborns also receive antibodies
in their mother’s milk
When Immune system cannot fight off an infection,
drugs may be used to help rid the body of pathogens.
 drugs that either kill bacteria only or prevent their
reproduction
• Penicillin, first antibiotic in 1928: used to be very resistant but with
antibiotic resistance it has become less effective
Antibiotic Resistance: ability of bacteria to survive treatment with
certain antibiotics
 When a colony of bacteria is exposed to an antibiotic, most of the
bacteria are usually killed
 Some will be resistant and those are the ones that survive and
reproduce, passing resistance off to their offspring
 This happens every time the antibiotic is used
 Why do you think Antibiotic Resistance has become a big problem in many
parts of the world?
Critical Thinking:
1. Animals infected with the virus that causes rabies often
salivate excessively and are apt to bite other animals even
when unprovoked. In a paragraph, explain how these
symptoms lead to the spread of the virus.
2. Getting vaccinated is much safer than getting the disease that
the vaccine prevents. However, like any drug, vaccines are
capable of causing side effects. Describe the benefits and risks
of vaccinations.
3. The ability of bacteria to resist antibiotics has become an
increasing public health problem. This problem is due to the
overuse and misuse of antibiotics. Suppose that one of your
friends always take antibiotics when he or she is sick. Write a
letter to your friend explaining the problem of antibiotic
resistance.