Transcript Infectious/Non-Infectious Disease

Your Immune System
Myth There isn’t much a person can do to avoid spreading
or catching a cold or the flu.
Fact About 80% of infectious diseases are spread by hand
contact. Washing your hands with soap and water is a
simple and effective way to prevent the spread of colds and
the flu.
Do you think most teens wash their hands as
much as they should? What do you think are some ways to
encourage more frequent hand washing?
What is the Immune System?
• The immune system is a network of
cells, tissues, and organs that work
together to:
– defend the body against “foreign”
invaders.
– produce, store, and carry white
blood cells that fight infections and
other diseases.
– detect and repair damaged cells.
• Also called the Lymphatic system.
Infectious/Non-Infectious
Disease
• Infectious Disease
– A disease caused by organisms
that enter and multiply within the
human body.
» Ex.- STD’s
• Non-Infectious Disease
– Disease that is not transmitted by
mean of a pathogen (disease
causing agent).
» Ex. – Cancer, Heart Disease
3 Categories of Non-Infectious
Diseases
Genetic
• Sex/Gender
• Familial
Disease
Tendency
3 Categories of Non-Infectious
Diseases
Lifestyle
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High Fat Diet
Lack of Sleep
Smoking/Smokeless Tobacco
Stress
Exposure to Sun
Lack of Exercise
Poor Nutrition
3 Categories of Non-Infectious
Diseases
Environment
• Polluted Air and Water
• Harmful Substances in Food
• Exposure to Sun
• Injury/Accident
Causes of Infectious Diseases
• Also known as communicable diseases,
infectious diseases are caused by organisms
or viruses that enter and multiply within the
human body.
• Microorganisms are organisms that can be seen
only through a microscope.
• Microorganisms and viruses that cause
disease are called pathogens
• Pathogens can cause an infectious disease
when they enter your body and multiply.
Bacteria
• Bacteria (bak TEER ee uh) are
simple, single-celled microorganisms.
Bacteria live in air, soil, food, and in
and on the bodies of plants and
animals, including you.
• Some bacteria injure cells by giving off
poisons called toxins (TAHK sinz).
Viruses
• The smallest pathogens are viruses.
• A virus can multiply only after
entering a living cell.
• The virus then takes over the cell’s
reproductive mechanisms, resulting
in cell damage or death.
How Pathogens Are Spread
• Pathogens can spread through contact with
• an infected person
• an infected animal
• contaminated objects
• contaminated food
• contaminated soil
• contaminated water
• The pathogens can then enter the body through
breaks in the skin or through the moist linings of the
eyes, ears, nose, mouth, or other openings.
Infected People
• Many infectious diseases are spread through some
form of contact with a person who has the disease.
• The contact may be direct physical contact.
• Infectious diseases
can also spread
through indirect
contact.
Infected Animals
Some infectious diseases are
transmitted to humans through
the bites of animals.
Contaminated Objects
• Some pathogens can survive for a period of time
outside a person’s body.
• These pathogens can be spread from person to
person on objects such as
• doorknobs
• eating utensils
• towels
• needles used for
body piercings
and tattoos
Contaminated Food, Soil, or
Water
• Some pathogens are naturally
present in food and soil.
• Sometimes water and food
become contaminated with
pathogens from infected people.
Quick Quiz Complete each of these statements with always, sometimes,
or never.
I ____ wash my hands before meals.
When preparing fruits and vegetables, I ____ wash them
thoroughly.
I am ____ careful to use only my own eating utensils,
drinking cups, towels and grooming items.
I ____ cover my mouth when I cough or sneeze.
If I spend time in wooded areas, I ____ wear
insect repellent.
For each of your responses, explain how your behavior could
affect your chances of getting or spreading an
infectious disease.
Physical and Chemical Defenses
Your body’s first line of defense against infectious
disease includes both physical and chemical
defenses that prevent pathogens from entering
your body.
Skin
• Your skin serves as both a physical and a chemical
barrier against pathogens.
• Sweat acts as a chemical barrier.
• Old skin cells are shed constantly, and the
pathogens on these cells are shed, too.
Mucous Membranes
• The openings into your body, such as your mouth,
eyes, and nose, are covered by protective linings
called mucous membranes
• Mucus traps many pathogens and washes
them away.
• Mucus contains chemicals and specialized cells that
attack pathogens.
Cilia
• Some of your body’s mucous membranes are lined
with tiny hairlike structures called cilia (SIL ee uh).
• Together, cilia and mucus help trap and
remove pathogens.
Saliva and Tears
• Your saliva and tears can trap pathogens and wash
them away.
• Saliva and tears also contain chemicals that attack
pathogens.
Digestive System
• Chemicals in your digestive system kill
many pathogens.
• The normal motions of the digestive system move
pathogens out.
• Bacteria that normally live in your digestive system
produce substances that can harm or kill
invading bacteria.
Inflammation
• Inflammation is your body’s general response to all
kinds of injury, from cuts and scrapes to internal
damage.
• Inflammation fights infection and promotes the
healing process.
Phagocytes
• Within seconds after your body is injured, the
damaged cells release chemicals that cause blood
vessels in the injured area to enlarge.
• Blood, other fluids, and white blood cells called
phagocytes (FAG uh syts) leak out of the
enlarged vessels.
• Phagocytes engulf and destroy pathogens.
Phagocytes
This micrograph shows a phagocyte (blue) attacking
bacteria (pink). Phagocytes kill pathogens by
engulfing and then digesting them.
Healing
• Phagocytes also give off substances that cause
healing to begin.
• The inflammation process heals the damage, and the
inflammation subsides.
The Immune System
The immune system fights disease by producing a
separate set of weapons for each kind of pathogen it
encounters.
The Immune Response
• When a pathogen enters your body for the first time,
it often causes disease.
• White blood cells called lymphocytes (LIM fuh syts)
carry out most of the immune system’s functions.
• If a pathogen that has previously attacked your body
enters your body again your immune system will
quickly recognize the pathogen and launch an
immediate attack.
• Immunity (ih MYOON ih tee) is your body’s ability to
destroy pathogens that it has previously encountered
before the pathogens are able to cause disease.
T Cells
T cells perform several functions.
• Killer T cells destroy any body cell that has been
infected by a pathogen.
• Helper T cells produce chemicals that stimulate
other T cells and B cells to fight off infection.
• Suppressor T cells produce chemicals that “turn
off” other immune system cells when an infection
has been brought under control.
B Cells
• The B lymphocytes, or B cells, produce antibodies.
• Antibodies (AN tih bahd eez) are proteins that
attach to the surface of pathogens or to the toxins
produced by pathogens.
• This binding action keeps the pathogen or toxin from
harming the body.
• The memory capacity of B cells explains why you
develop immunity to some diseases you’ve already
had.
The Immune Response