Understanding Diseases

Vocabulary• Epidemic – a widespread occurrence of a disease.• Bacteria – small, single-celled organisms found

almost everywhere. Millions of beneficial bacteria live in your body to protect you from harmful bacteria that cause infection.

• Antibiotic – a drug that kills or slows the growth of bacteria. Penicillin is the most commonly used antibiotic

• Virus – an extremely small particle that consists of an outer shell and genetic material. Viruses are not living organisms – they cannot reproduce themselves.

• Vaccines – a weak or dead strain of a virus given to a healthy person so they can develop antibodies against a particular virus

• Immune system – organs and special cells that fight infection

• Immune response – the reaction of the body to a germ that has gotten past the physical barriers of the defense system (skin, hairs, tears, mucus, saliva and stomach acid)

Flu virus

The Immune response – antigens are proteins on the surface of a cell (bacteria, fungus or virus) that our bodies recognize as foreign invaders

Killer T Cells ->

White blood cell

Disease = any harmful change in the health of your body• Infectious Disease is any disease

caused by pathogens that invade the body

• Pathogen = any organism capable of producing disease– Virus – flu (throat, lungs, muscles),

chickenpox (skin), hepatitis (liver)– Microorganism

• Bacteria – cold (nose, throat, lungs), strep throat (throat), tuberculosis (lungs)

• Fungi – athlete’s foot (feet), ringworm (skin)• Protozoa – malaria (carried by mosquitoes)• Parasite – Lyme’s disease (ticks)

bacteria

virus

A disease which can be passed directly from one person to another is called a communicable disease.

• Noninfectious Disease is a disease that is not caused by a pathogen.

• Cancer – Lymphomas (immune system), Leukemia (blood), Carcinomas (skin, lungs, digestive tract), Sarcomas (bones, ligaments and muscle)

Noninfectious diseases can be inherited, triggered by something in the environment or be caused by lifestyle choices (an unhealthy diet can cause Type 2 Diabetes).

• Body System diseases– Cardiovascular – High blood pressure, clogged arteries, heart

disease, Congenital Heart Defects, Hemophilia– Respiratory – Allergies, Asthma, Emphysema, Bronchitis,

Pneumonia, Tuberculosis– Skeletal/Muscular – Muscular Dystrophy, ALS, Osteoporosis,

Scoliosis, Joint injuries, Carpal Tunnel Syndrome, Hernia, Tendonitis

– Nervous System – Head and Spinal Cord injuries, Parkinson’s Disease, Multiple Sclerosis, Alzheimer’s disease, Epilepsy, Cerebral Palsy, Spinal Bifida

– Digestive System – Gallstones, Appendicitis, Lactose Intolerance, Ulcers, Cirrhosis, Crohn’s Disease, Colitis, Hemorrhoids

Defense Against Disease• Skin – outer defense

includes also nose hair, eyebrows and eyelashes

• Mucous Membranes – mucus is a sticky fluid that traps pathogens… they line your mouth, nose, eyes, throat and others places.

• Sweat, Saliva and Tears contain chemicals that kill bacteria

• Stomach Acid – kills most of the pathogens found in food and drink.

• The Immune System – White blood cells remove pathogens from your blood and your Lymphatic system circulates antibodies.

Lymphatic System

Prevention and Treatment

• The 5 causes of infectious diseases are…• Viruses• Bacteria• Protozoa and parasites• Fungi

• Most bacterial diseases can be treated with antibiotics• Antibiotics and other drugs (medicines) are available to

treat most diseases caused by Protozoa and other parasites.

• Fungi are often treated by antifungal creams and powders.

• In tropical countries, malaria kills 1-2 million people every year. It is difficult to stop this disease because it is impossible to eliminate mosquitoes in some places. Sleeping under mosquito netting does help prevent malaria.

Malaria affected areas

• Some ways to control the spread of disease in your home are…

• Wash your hands• Keep your kitchen clean• Don’t share drinking glasses or

eating utensils with someone who is sick.

• Get treatment if you are sick before it spreads to others

• If the water supply has harmful bacteria in it, boiling the water or treating it with certain chemicals will help stop the spread of the bacteria.

Clean water

Dr. Edward Jenner - Vaccines

• 1798 by using pus from a mild disease called cowpox to inoculate a boy against a deadly disease called smallpox.

• As a doctor, he had noticed that milkmaids who had recovered from cowpox did not get smallpox… he did not know what actually caused the disease.

• At the time, smallpox was responsible for about half a million deaths a year with 20-60% of all those infected – and over 80% of infected children – dying from the disease.

• In 1979 the World Health Organization certified the eradication of smallpox and to this day it is the only human infectious disease to have been completely eradicated.

• Vaccines stimulate your immune system to produce antibodies which fight invading pathogens caused by viruses

• Pathogens are all around you. How can you prevent the spread of common infectious diseases?

• Get vaccinated • Avoid direct or indirect contact with other

people when you or they are sick • Protect yourself against insect bites • Consume food and water you know is safe

(not contaminated) • Treat any illness quickly • Keep your body healthy