The Immune System Packet #22 Chapter #31

Body responds to pathogen Introduction The immune system includes all of the structures and processes that provide a defense against potential pathogens (disease causing agents). Immunity, the ability of an organism to resist disease, are in two forms Passive Immunity Immunity passed from mother to child Via genes There is no immune response Active Immunity The body produces a response to a particular pathogen. Immunity Passive Mother to Child Genes Active Body responds to pathogen Response to Pathogen

Human Body Defense Mechanisms Active Immunity

Human Body Defense Systems Defense Mechanisms Lymphocytes Non-Specific Rapid Specific Several Days Defense Mechanisms Non-Specific Defense is a rapid response to a wide range of pathogens Specific Takes several days to mount Delivered by the Immune System Lymphocytes Saturday, April 22, 2017

Lymphocytes

Introduction Lymphocytes T Cells Thymus-dependent B Cells Bursa of Fabricius Lymphocytes (a type of white blood cell) are derived from unspecialized stem cells in the bone marrow. Large numbers of lymphocytes are found in the thymus, spleen and lymph nodes. There are two types of lymphocytes T cells Thymus-dependent lymphocytes B cells Derived from the discovery of B cells in the bursa of Fabricius Mammals do not have this organ Which type of stem cells should be found in the bone marrow?

B Cells Secrete antibodies (proteins) into the blood and lymph in order to inactivate pathogens. Combat bacterial infections and some viral infections Because blood and lymph are body fluids (humors), and since they release antibodies, the B cells are said to provide humeral immunity (antibody-mediated immunity) Types of B cells include Memory B cells Plasma cells

T Cells Attack host cells that have become infected with viruses or fungi, transplanted human cells and/or cancerous cells. These cells do not secrete antibodies. Must be in close proximity to destroy the infected cell. Provide cell-mediated immunity. Cell-mediated immunity involves the use of T cells. Types of T cells Killer T Cells AKA Cytotoxic T cells Helper T Cells Suppressor T Cells

Humoral Immuntiy vs. Cell-Mediated Immunity See Pages 764 & 765 in textbook.

Specific Mechanisms

Specific Defense Mechanisms Antigens Molecules (proteins), found on the surface of cells, that stimulate the production of specific antibodies. The ID card. Natural Foreign Haptens Small organic molecules that can become antigens if they are bond to proteins. Immunoassays* Specific Defense Mechanisms Antigens Haptens Immunoassays

Non-Specific Mechanisms/Barriers *Happens the same way for each pathogen?

Non-Specific Defense Mechanisms Phagocytosis Neutrophils Macrophages Phagocytes Fever Interferons Messengers Phagocytosis Engulfing of pathogens Neutrophils Macrophages Phagocytes Fever Produced by cytokines High fevers are dangerous however fevers aid in the destruction of pathogens Interferons Polypeptides that act as messengers that protect other cells in the vicinity from viral infection.

Introduction The non-specific defense systems utilizes different “defensive lines” in order to be successful. {*Similar to having an alarm system for the house but there are specific sensors, at the doors and windows for example, that trigger the alarm system.} Similar to having an alarm system for the house but there are specific sensors, at the doors and windows for example, that trigger the alarm system.

The Immune System Non-Specific Defense System Barriers/Mechanisms The First Line of Defense The Skin Mucous Membranes Cilia Lines the lungs Gastric Juice In the stomach Kills most microbes Saturday, April 22, 2017

The Immune System Non-Specific Defense Barriers/Mechanisms The Second Line of Defense Inflammatory Response Redness; swelling; heat; pain Lymphocytes are activated. Fever is developed. Saturday, April 22, 2017

The Immune System Non-Specific Barriers/Mechanisms The Third Line of Defense Consists of mechanisms and agents that target specific antigens Via the use of lymphocytes. Saturday, April 22, 2017

Over Active Immune System

Allergies An allergy is an oversensitivity to a normally harmless antigen. Harmless antigens, that cause the over-the-top response, are known as allergens. Food Peanuts Airborne Pollen Pet dander Mold Chemical Penicillin Jewelry metals

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