The Body’s Defense System Chapter 31 The Body’s Defense System Poke me!

The Germ Theory of Disease Diseases are spread from one organism to another, by microscopic particles

Pathogen Any disease causing organism or virus (Ex.) bacteria, fungi, virus, protists

Infectious diseases Are caused by pathogens and can be transmitted to other healthy organisms

Transmission of Infectious Diseases Airborne Physical contact Contaminated food or H2O Sexual contact Animals (ex. Lyme disease)

The human body has three lines of defense against infections

The First Line: Barriers Physical & chemical non-specific defenses, (that means they prevent many different diseases from infecting us)

Examples: Skin, Hair Mucous membranes Saliva Stomach acid & enzymes Sweat, tears

The Second Line: Internal Nonspecific Defenses 3 types: White blood cells Inflammatory response Specialized proteins

remove any foreign materials, by phagocytosis White Blood Cells Macrophages & neutrophils remove any foreign materials, by phagocytosis

Macrophage and E. coli pink = macrophage yellow = bacteria; note rod-like structure of bacillus

macrophage after a bacterium (pathogen)

White Blood Cells Natural killer cells kill our cells infected with a pathogen, thus killing the pathogens too.

The inflammatory Response is recognized by: Redness, heat, swelling, pain Histamine causes blood vessels to dilate (expand) That increases blood supply

Specialized Proteins Produced by cells Ex. Interferon Help remove pathogens

The Third Line: Targeted Defense Specifically target a single disease Immune system can recognizes our cells(“self”) vs. (“non-self”) cells

3rd Line the IMMUNE RESPONSE If a pathogen gets by the 2nd line of defense: Cells are programmed to attack and destroy

Antigens & Antibodies Antigen: proteins on ‘nonself’ cells that begin an immune response

Antibodies proteins produced by our immune systems to remove specific pathogens.

Lymphocytes WBCs that are designed to remove SPECIFIC invaders 2 types: B cells & T cells

B Cells Develop in Bone marrow Produce antibodies

Cytotoxic T cells Mature in the Thymus Destroy host cells infected with a pathogen.

Helper T cells Attach to antigen displayed on a WBC Program cytotoxic T cells and B cells to destroy that pathogen

Memory Cells Both type B & T lymphocytes produce memory cells to respond more quickly to the same pathogen

The Third Line of Defense The Immune Response The Third Line of Defense

A Summary of the Immune Response

1. Macrophage (WBC) ingests pathogen (phagocytosis) 2. Pathogen is digested, antigen is displayed

3. WBC shows the antigens 4. Helper T cells bind to antigens

5. Helper T cells activate T cells and T memory cells

Chemical Secretion Memory T cells Helper T cells activate TC & TM cells Chemical Secretion TC cells destroy pathogen Memory T cells

Next, B cells are activated (programmed) B cells multiply Memory B cells are made B ‘s become Plasma B cells & secrete… Antibodies (destroy pathogen)

ABO Blood Groups Blood typing is determined by the antigens present on the surface of the RBCs. There are A & B antigens

This results in Four possible blood types: Blood Groups This results in Four possible blood types: A, B, AB, O

BLOOD TYPE A

BLOOD TYPE B

BLOOD TYPE AB

BLOOD TYPE O

A B AB O BLOOD TYPE A B A & B neither A nor B Blood Type RBC Antigens Present Blood Type A B A & B neither A nor B A B AB O

Antibodies Present in Plasma BLOOD TYPE Blood Type Antibodies Present in Plasma A B AB O B A None A & B

A O B O A B AB O O A B AB O BLOOD TYPE Blood Type Universal Recipient Can Receive Type: A B AB O A O B O A B AB O O Universal Recipient

A AB B AB AB A B AB O A B AB O BLOOD TYPE Blood Type Universal Donor Can Donate To: A B AB O A AB B AB Universal Donor AB A B AB O

Blood Typing Game

Plasma Donations In an emergency situation plasma may be transfused instead of blood cells. Why?? No typing is necessary!

Organ Transplants Possible rejection because body is recognizing “self” versus “non-self” tissues Medications suppress immune system to decrease rejection  but lowers defense system against other infections

Vaccines stimulate the immune response

Vaccine development Edward Jenner 1796, used cowpox to provide immunity to small pox Louis Pasteur 1885, developed vaccines for rabies & anthrax Jonas Salk/Albert Sabin 1955, Salk developed injectable vaccine for polio 1961, Sabin developed an oral vaccine The term vaccine comes from vaccinus, Latin for “from cow”. Jenner was an English doctor who noticed that milkmaids who were exposed to cowpox didn’t contract the more virulent disease of small pox. Jenner injected a milkmaid that had not contracted cowpox with that pathogen. The milkmaid developed immunity to smallpox. Pasteur studied anthrax, a fatal disease of cattle, and developed a weakened or attenuated form of the bacteria that causes the disease. He inoculated 25 sheep with the vaccine and then inoculated this group and an additional 25 sheep with the anthrax bacillus several days later. The 25 sheep that had not been vaccinated died, while the vaccinated sheep were protected. He also worked on developing a vaccine for rabies and performed the first successful test on a young boy whose mother pleaded with Pasteur to treat her son after the boy had been bitten by a rabid dog. The boy underwent treatment with vaccinations for 10 days and recovered completely. Polio is a disease of the central nervous system, specifically the spinal cord and is caused by a virus. Previously, the greatest incidence of the disease was in children between the ages of 5 and 10. There were over 57,000 cases of polio diagnosed in 1952. Because we have an effective polio vaccine, very few cases of the disease are diagnosed each year. The first vaccine was developed by Jonas Salk. The Sabin oral polio vaccine is the type most commonly administered in the U.S. Koch’s Postulates are still used as the standard protocol today to prove that a pathogen causes a specific disease. A diagram of the process can be found on the next slide, entitled “Vaccine development uses Koch’s Postulates”.

Vaccines Dose of a pathogen or part of a pathogen that is disabled or destroyed  no longer harmful

Vaccines Different types: Use just antigens of pathogen Grind or heat pathogen so it can’t function Similar version of pathogen Booster shots

Stages in Vaccine-Induced Immunity

Active Immunity When your body produces antibodies against an infection

Active Immunity 2 examples: Previous infection Vaccines

Passive Immunity When you receive antibodies from another source

Passive Immunity Examples: Fetus from mother Traveling  antibodies temporarily protect

Disorders of the immune system are major health problems Use textbook to fill in page 6 in your notes