Download Section 4 Infectious Diseases

Do Now: Define
•
•
•
•
•
•
•
•
•
•
•
•
Infectious Disease
Pathogen
Microorganism
Tetanus
Antibodies
Active immunity
Passive immunity
Vaccine
Bacteria
Virus
Fungi
Protozoan
INFECTIOUS
DISEASES
• Infectious Disease- are caused by
organisms or viruses that enter and
multiply within the human body.
• Pathogens – can cause infectious
disease when they enter your body
and multiply.
Examples of Pathogens
•
•
•
•
•
Bacteria
Viruses
Fungi
Protozoans
Other pathogens
Bacteria -
single-celled
microorganisms
• Live everywhere air, soil, food, on
the bodies of animals, plants and
humans
• Most bacteria are not pathogens
• Can produce a toxin – a substance
that kills cells or interferes with
their functions
Viruses
• Are the smallest pathogens
• Can only multiply after entering a
living cell
• Invade different types of cells
• Ex. – common cold invades the
respiratory tract
Fungi
• Organisms such as yeasts,
molds, and mushrooms that
grow best in warm, dark, moist
areas.
• Ex. Athletes foot and ringworm
Protozoans
• A large and complex singlecelled organism.
• Have the ability to move
through fluids in search of food.
• Ex. Malaria
Other Pathogens
• Caused by:
•
•
•
•
Animals
Mites
Lice
And certain worms
How are Pathogens
spread?
• A.) Contact with an infected
person.
• B.) Infected animal
• C.) Contaminated objects
• D.) Contaminated food, soil or
water
Infected People –
some form
of contact with a person who has the
disease
• Direct physical contact:
•
•
•
•
•
Shaking hands
Kissing
Hugging
Touching
Sexually transmitted
• Indirect contact:
• If an infected person coughs or sneezes,
you can inhale the pathogens in tiny
droplets of moisture in the air.
• Blood – needles
• Chicken pox and measles can spread by
droplet infection
Infected Animals
• Bites from an infected animal
(dog or raccoon)
• Rabies – deadly disease of the
nervous system
• Malaria- mosquito bites
Contaminated Objects
• Pathogens can survive for a period of time
outside a person’s body.
• Can be spread from person to person on
objects doorknobs, towels, cups
• Touching something that has been
contaminated can be transferred to you
when you touch your mouth or food
Contaminated Food, Soil
or Water
• Food poisoning:
• Salmonella (bacteria)– poultry, meat
and eggs
• E. Coli-beef
• Cook foods thoroughly to kill these
bacteria
Defenses Against
Infection
• Physical and Chemical
• Inflammation
• Immune system
Physical and Chemical
• Your bodies first line of defense is its
protective coverings.
• Ex.- Skin is a physical barrier to
pathogens
• Sweat is a chemical barrier – contains
acids that kill many bacteria.
• Skin sheds old cells and the pathogens
on them are spread too
Those include:
• A.) Skin- are hard and have no gaps between them.
• B.) Mucous membranes- the protective lining that
covers any opening into the body (mouth, eyes and
nose)
• What is does with pathogens:
• They secrete mucous which is a sticky liquid
which traps many pathogens and washes them
away.
• C.) Cilia- tiny hairlike structures that line
some of the mucous membrane.
• When you cough or blow your nose the
pathogens are removed along with the mucus
• D.) Saliva and tears- trap pathogens and
wash them away.
• E.) Digestive system – acids in
your stomach, kill many
pathogens.
Second line of defense: Inflammation
• Inflammation – is your body’s general
response to all kinds of injury, from cuts,
scrapes to internal damage caused by
infectious diseases.
• Fights infection and promotes the
healing process
• Inflammation process begins within
seconds after injury
• Damaged cells release chemicals that cause
several responses
• Tiny blood vessels in the injured area enlarge,
allowing more blood to flow to the area.
• Fluids leak out of the blood vessels along with
cells called Phagocytes.
Phagocytes – white blood cells that
“eat up” foreign cells
• Process:
• A. Phagocyte “spots” pathogen
• B. Phagocyte begins to surround
pathogen
• C. Phagocyte engulfs pathogen
• D. Phagocyte digests and kills pathogen
3rd defense = Immune
System
• Fights disease by producing a separate set
for each kind of pathogen it encounters.
• Made up of cells in your blood, lymph, bone
marrow, and other tissues.
• Immunity- is your body’s ability to destroy
pathogens that it has previously
encountered before the pathogens are able
to cause disease.
• Lymphatic system is a network of vessels
that collects fluid from the tissues of your
body and returns it to the blood.
• Lymphocytes – white blood cells that
carries out most of the immune system’s
functions.
• B cells – produce antibodies
• T cells- 3 types that live blood of the lymphatic
system
T Cells
• Helper “T” cells
• Killer “T” cells
• Suppressor “T” cells
Helper “T” cells help fight infection
Passive Immunity
• Is acquired by receiving
antibodies from a source other
than one’s own immune system.
• Temporary
• Example – newborn babies
Active Immunity
• Immunity that your immune
system creates
• Immunizations/vaccination – an
injection that causes the body to
become immune to an infectious
disease
• Vaccine – contains small
amounts of dead or modified
pathogens or their toxins that is
injected during an
immunization.
Bacterial Diseases
• Strep Throat –sore throat, fever, enlarged
lymph nodes. Treated with antibiotics.
• Lyme Disease - caused when bitten by an
infected deer tick.
• Tuberculosis
• Bacterial Meningitis
Treating Bacterial
Diseases
• Antibiotic- a drug that inhibits or kills
bacteria.
• Prescription medicine only available with a
written order from a qualified healthcare
professional.
• Important to use as prescribed to avoid
developing resistance from the medication.
Viral Diseases
• Common Cold - group of symptoms caused
by a number of different viruses
• Influenza- common viral infection of the
upper respiratory system.
• More serious illness in infants and the
elderly.
• Pneumonia- an infection of the lungs in
which the air sacs fill with pus and other
liquids.
**A serious infection to the lungs.
Many people die each year from pneumonia
which can be caused by viruses, bacteria
or fungi.
• Hepatitis- inflammation of the liver.
Caused by chemicals and many other
pathogens. No cure – but vaccines for A
and B.
• “A” – spread through contact with feces
of an infected person. Not washing hands
properly before handling objects or food.
• “B” – more serious than “A”. Found
in most bodily fluids, especially
blood. Transmitted sexually. Drug
use, piercings, tattoos, etc.
• “C” – most common, transmitted by
direct contact with infected blood.
Treating Viral Diseases
• No particular medicine that can cure a
viral infection, can take over the counter
medications.
• Antibiotics for instance are only effective
against bacteria not viruses.
• Best treatment for viral infections are rest,
a well-balanced diet and plenty of fluids.
5 stages of Illness
• 1.) Incubation - virus enters the
body and multiples, you feel
fine.
• 2.) First symptoms
• 3.) Severe symptoms
• 4.) Recovery
• 5.) End of infection
3 Ways to Prevent
Illness
• 1.) Avoid contact with pathogens
• 2.) Make sure your immunizations
are current
• 3.) Choose healthy behaviors
Other ways of Prevention:








Washing hands
Handling Food Properly
Balanced Diet
Avoid sharing
Proper Food Storage
Unnecessary Contact with people who are
ill
Vaccinations
Abstinence