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 single-celled 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:Other ways of Prevention:

Washing handsWashing hands Handling Food ProperlyHandling Food Properly Balanced DietBalanced Diet Avoid sharingAvoid sharing Proper Food StorageProper Food Storage Unnecessary Contact with people who are Unnecessary Contact with people who are

illill VaccinationsVaccinations AbstinenceAbstinence