The Body’s Defenses California Standards 10.a., b. & c.

Pathogens Pathogens are disease causing agents such as: 1. bacteria 2. viruses 3. prions and 4. single cell organisms

First Line of Defense Skin: prevents pathogens from entering the body

Skin = the first line of defense The skin is the organ which defends the body from infection by blocking the entry of pathogens.

2. Mucous Membranes: found in your nose and throat and stop the entry of pathogens into your body.

Second Line of Defense Inflammatory Response Temperature Response Proteins White Blood Cells

1.Inflammatory Response A series of events that suppress infection and speed recovery Histamine: increase blood flow by dilating blood vessels. White blood cells invade infected area Swelling and redness occurs

When the skin is punctured pathogens are allowed to enter the body. capillary

Injured or damaged cells release the chemical histamine which causes the blood vessels to dilate increasing blood flow to the area. This blood flow causes swelling and redness to the area.

Increased blood flow bring white blood cells that attack and destroy pathogens. The presence of ‘puss’ at a wound is the presence of white blood cells.

2. Temperature Response 1. Higher temperature called a fever 2. Bacteria do not grow well at high temperatures 3. Enzymes are destroyed or denatured

Temperature Response Basically, the temperature is a response that is helpful in fighting pathogens because bacteria do not grow well at high temperatures.

Bacteria and Antibiotics Antibiotics are specifically used to kill bacterial infections. They do nothing for viral, or virus caused, infections.

3. Proteins 1. Complementary System made up of 20 different proteins. 2. Punctures cell membrane of bacteria 3. Interferon released to fight viruses

4. White Blood Cells Neutrophils Macrophages Natural Killer Cells

Neutrophils Engulf and destroy pathogens Release chemicals that kill bacteria and themselves

Macrophages Kill and ingest pathogens Clear dead cells and other debris Found in spleen and lungs

Natural Killer Cells Attacks cells infected with pathogens Puncture cell membrane Detect and kill cancer cells

Nonspecific Defense: Skin Mucous membranes Inflammatory response Temperature Protein White blood cells

Third Line of Defense

Specific Defense Against Disease The last type of defense against invading organisms is the specific line of defense. This defense by your body attacks specific pathogens and in the process produces antibodies that in the future can attack that specific pathogen if it occurs again.

Third Line of Defense Immune Response: consists of an army of cells that combat specific pathogens Antigen: a substance that triggers an immune response Antibody: a ‘Y-shaped molecule that is produced by plasma cells when exposed to an antigen.

Non-functioning immune response A person’s immune response is not functioning well if it is unable to fight pathogens. This is because their body cannot produce the specific antibody for that pathogen. AIDS is just such a disease because a patient’s body inability to defend itself against invading organisms.

Antibodies and Antigens An antibody is produced by your body in response to a specific antigen. An antigen is a foreign substance which causes the body to produce a specific antibody.

Antibodies attacking an antigen ‘Y’ shaped antibody

Antibodies Antibodies are substances formed by the human body in response to foreign proteins entering the body.

Resistance to Disease Immunity – resistance to a particular disease. Vaccination – a medical procedure used to produce immunity. Vaccine – a solution of dead or modified pathogens that can no longer cause disease.

Vaccines and Infection Vaccines are effective in preventing disease because they are dead or modified pathogens with antibodies directed against a specific pathogen.

The End