BODY DEFENSES AND DISEASE

The 5th Guy

CAUSES OF DISEASE Noninfectious Disease

When you have a disease, your normal body functions are disrupted.

Noninfectious disease ARE NOT spread from person to person

CAUSES:SmokingLack of physical activityHigh-fat diet

CAUSES OF DISEASE Infectious Disease

Infectious disease CAN be passed from one living thing to another.

CAUSED BY:Pathogens: virus,

microorganism or other organisms that cause disease.

PATHWAYS TO PATHOGENS

AIR: Some pathogens travel through the air

*Example: a single sneeze

CONTAMINATED OBJECTS: If you share objects with an infected person, you can become SICK!

*Example: contaminated doorknobs, keyboards, combs, and towels

PERSON TO PERSON: Some pathogen are spread by direct person

*Example: kissing, shaking hands or

The 5th Guy 2

PATHWAYS TO PATHOGENS

ANIMALS: Some pathogens are carried by animals Example: humans can get a fungus

called ringworm from handling an infected dog.

FOOD AND WATER: Drinking water in the United States is generally safe. But water lines can break allowing germs to enter.

Bacteria growing in foods and beverages can cause illnesses Example: meat, fish, and eggs that

are not cooked enough

PUTTING PATHOGENS IN THEIR PLACE

PASTEURIZATION During the mid-1800s, Louis Pasteur

discovered that microorganism cause wine to spoil.

Pasteur devised a method of using heat to kill most of the bacteria in wine and milk.

VACCINES AND IMMUNITY In the late 1700s, no one knew what a

pathogen was. Edward Jenner studied a disease called

smallpox. He observed that people who had been

infected with cowpox seemed to have protection against smallpox.

PUTTING PATHOGENS IN THEIR PLACE

ANTIBIOTICSHave you ever had strep throat?An antibiotic is a substance that

can kill bacteria or slow the growth of bacteria

Viruses, such as those that cause colds, are not affected by antibiotics.

Antibiotics can kill only living things.

A virus is NOT a living thing.

The 5th Guy - Flu

Vaccines

A substance prepared from killed or weakened pathogens.

Stimulates the body to produce immunity.

Used to trigger the body to make memory cells for a specific pathogen

How could a vaccine prevent the spread of disease?

How is being vaccinted similar to being infected with a disease?

How is it different?

YOUR BODY’S DEFENSESFIRST LINE OF DEFENSE

For a pathogen to harm you, it must attack a part of your body.

YOUR BODY’S FIRST LINE OF DEFENSE IS YOUR SKIN!

Your skin is made of many layers of fat cells. The outermost layers are dead.

As a result, many pathogens that land on your skin have difficulty finding a live cell to infect

YOUR BODY’S DEFENSESFAILURE OF THE FIRST LINES OF

DEFENSESometimes, skin is cut or

punctured and pathogens can enter the body.

THE BODY ACTS QUICKLY!Blood flows to the injured areaCell parts in the blood called

platelets, which help seals the wound.

The increased blood flow also brings cells that belong to the IMMUNE SYSTEM.

CELLS OF THE IMMUNE SYSTEM

The immune system consists mainly of three kinds of cells.

MACROPHAGEBIG EATERS

Engulf and digest microorganisms or viruses.

If only a few microorganism or viruses have entered a wound, the macrophages can easily STOP THEM.

It alerts the rest of the immune system of invaders

CELLS OF THE IMMUNE SYSTEM

Lymphocytes - T cells and B cells

On the surface of each lymphatic cell are receptors that

enable them to recognize foreign substances. These

receptors are very specialized - each can match only one

specific antigen.

Helper T Cell

Helper T cells are the major driving force and the main

regulators of the immune defense. Their primary task is to

activate B cells and killer T cells. The killer T cell is

specialized in attacking cells of the body infected by

viruses and sometimes also by bacteria. It can also attack

cancer cells.

CELLS OF THE IMMUNE SYSTEM

B Cells The B lymphocyte cell searches for antigen

matching its receptors. If it finds such antigen it

connects to it, and inside the B cell a triggering

signal is set off.

The plasma cell is specialized in producing

specific protein, called an antibody, that will respond

to the same antigen that matched the B cell

receptor. Antibodies are released from the plasma

cell so that they can seek out intruders and help

destroy them.

Challenges to the Immune System

Allergies – over reaction to foreign antigens that are not dangerous to most people. (ex. Peanuts, penicillin, mold, etc.)

Cancer – a group of diseases in which cells divide at an uncontrolled rate. (ex. Skin cancer)

Immune Deficiency – HIV/AIDs; specifically infects the T-cells.

Auto-immune Diseases – cells mistake body cells for foreign antigens; ex rheumatoid arthritis

What is the differenece between an allergy and an autoimmune disease?

In an autoimmune disease, the immune system attacks the body’s own cells. In an allergy, the immune system reacts to foreign cells that are for the most part harmless; such as pollen, foods or medicine.