Challenge Problem

Body Defenses: The Immune System 12c

Let’s Review Pathogens- 8min Something that makes us sick, causes disease -Use your phone to find 5 pathogens, quick description and an example of a disease they cause. If you know one from memory you can write that down. 1- pathogen example ex- disease example 2- ex- 3- ex- 4- ex- 5- ex-

Third Line of Defense: Immune System

Specific Defense: The Immune System Important Aspects Antigen specific recognizes and acts against particular foreign substances Systemic not restricted to the initial infection site Has memory recognizes and mounts a stronger attack on previously encountered pathogens

Types of Immunity Humoral immunity Cellular immunity Antibody-mediated immunity Cells produce chemicals for defense Cellular immunity Cell-mediated immunity Cells target virus infected cells Slide 12.25 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

So, how does the immune system know which cells to attack?

Antigens Antigen Surface Proteins that identify the cell Self: found on cells that belong to the organism Non-Self: found on cells that do not belong to the organism invaders

Antigens (Nonself) Any substance capable of exciting the immune system and provoking an immune response Examples of common antigens Foreign proteins Nucleic acids Large carbohydrates Some lipids Pollen grains Microorganisms Slide 12.26 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Self-Antigens Human cells have many surface proteins Our immune cells do not attack our own proteins. They only attack “foreign” proteins. Our cells in another person’s body can trigger an immune response because they are foreign Restricts donors for transplants Slide 12.27 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Quick Quiz What is an antigen? (in your own words) Why are antigens so important in the immune response?

Let’s review the cells involved in the immune system

Cells of the Immune System Lymphocytes Originate from hemocytoblasts in the red bone marrow B lymphocytes become immunocompetent in the bone marrow T lymphocytes become immunocompetent in the thymus Macrophages Arise from monocytes Become widely distributed in lymphoid organs Slide 12.29 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Activation of Lymphocytes Figure 12.9 Slide 12.30 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Immune Response: Humoral Immunity Involves Antibodies!!

Humoral Immunity 1) B-Cells recognize and attach to a foreign antigen 2) B-Cells reproduce Plasma Cells: produce Antibodies specific to attack this antigen Memory Cells: for quick attacks on future encounters with this antigen.

Humoral Immunity 3) Antibodies bind to foreign antigens on cells and disable them 4) Macrophages engulf and destroy cells that have antibodies attached.

Humoral Immune Response Figure 12.10 Slide 12.32 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Secondary Response Memory cells are long-lived A second exposure causes a rapid response The secondary response is stronger and longer lasting Figure 12.11 Slide 12.33 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Quick Quiz Why is humoral immunity also called “Antibody-mediated Immunity”? What type of lymphocyte is involved in Humoral immunity?

Active Immunity: Permanent Your B cells encounter antigens and produce antibodies Active immunity can be naturally or artificially acquired Get Sick Get an immunization shot Figure 12.12 Slide 12.34 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Passive Immunity: Temporary Antibodies are obtained from someone else Conferred naturally from a mother to her fetus Conferred artificially from immune serum or gamma globulin Immunological memory does not occur Protection provided by “borrowed antibodies” Slide 12.35

Antibody Structure (draw it) Four amino acid chains linked by disulfide bonds Two identical amino acid chains are linked to form a heavy chain Slide 12.38a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 12.13b

Antibody Classes Antibodies of each class have slightly different roles Five major immunoglobulin classes IgM – can fix complement IgA – found mainly in mucus IgD – important in activation of B cell IgG – can cross the placental barrier IgE – involved in allergies Slide 12.39 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Antibody Function Antibodies inactivate antigens in a number of ways Complement fixation Neutralization Agglutination Precipitation Slide 12.40 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Quick Quiz Name two ways to get “Active Immunity” How can you get “Passive Immunity”? What is the primary difference between active and passive immunity?

Antibody Act-ivity Read the ½ sheet of paper and be prepared to get a part After a demo, you will be moving around the room like bacteria, antibodies, B-cells, and macrophages!!

Assignment Create a 6-frame comic strip that outlines the humoral immune response steps. Must have colored pictures Must clearly explain each step of the response. Be creative!!