•1 The Germ Theory of Disease

infectious diseases were caused by germs.

Chapter 47- Non Specific Defenses

Immune System

Diseases are caused by pathogens.

•A disease is any change, other than an injury, that disrupts the normal functions of the body.

• Pathogens are destroyed by the body’s immune system.

attacks and “remembers” each pathogen

• Agents of Disease

•viruses•bacteria•protists•worms•fungi

•Diseases Are Spread by– coughing– sneezing – physical contact – contaminated water or food – infected animals

Transmission of Disease1. Direct Contact – touching an infected person

2. Indirect Contact – touch infected surfaces or breath in pathogens from the air.

3. Ingestion – drinking contaminated water or eating contaminated food

• Vectors- organism that carries diseases and bites you.

1st Line of Defense - Nonspecific

• JOB- keeps pathogens out of the body. • Skin-

• Most Important• Mucus and sweat • Cilia in the nose

• Tears• Stomach acid and digestive enzymes

•Second line of Defense: Specific Defenses

When activated by a pathogen it’s called an immune response. Any substance, such as a virus or bacterium, that triggers this response is known as an antigen.

•If a pathogen enters the body it makes an inflammatory response.

-is a non-specific defense reaction to tissue damage caused by injury or infection.

•Histamines Released-increase blood flow to injured area

•Phagocytes- ingest and destroy pathogens and foreign matter•Neutrophine•Macrophage•Natural Killer cells

• Antibodies which are proteins that recognize and bind to an antigen marking it for destruction.

• Memory cells- remember pathogens• B lymphocytes (B cells)-defend the body against antigens and pathogens in body fluids.

• T lymphocytes (T cells)-defend the body against abnormal cells and pathogens inside living cells.

Antigen

Antibody

Second Line of Defense - NonspecificInflammatory Response1. Damaged tissues release histamines, increasing blood

flow to the area.2. Histamines cause capillaries to leak, releasing phagocytes

to the wound.3. Phagocytes engulf bacteria and destroy it4. Platelets move out of the capillary to seal the wounded

area.

Skin

Phagocytes move into the area and engulf the bacteria and cell debris

Capillary

Bacteria enter the wound

Wound

•17 There are three different types of immune system disorders:

•18 There are three different types of immune system disorders:

• allergies

•19 AllergiesAn overreaction to a common

antigen.

pollen, dust, mold, and bee stings.

autoimmune disease

the body attacks itself.• Some examples of autoimmune diseases

include:• Type I diabetes

• Rheumatoid arthritis

•22 Immunodeficiency Diseases

a weakened immune response

•23 Immunodeficiency Diseasescan be

caused by the HIV virus.

•24 HIV attacks and destroys “helper” T-cells.

•As the number of helper T cells decreases, the body becomes more susceptible to other diseases.