CHOOSE HAPPINESS! “ The basic thing is that everyone wants happiness, no one wants suffering; And happiness mainly comes from our own attitude rather than external factors. If your own mental attitude is correct, even if you remain in a hostile environment, you feel happy.” -Tenzin Gyatso, 14 th Dalai Lama

THE IMMUNE SYSTEM “System of defense against pathogens” Please refer to pages 1-5 of your Common Diseases of Companion Animals book and pages in your Clinical Anatomy and Physiology book

Immunology Immunity – The ability of the body to fight infection and/or foreign invaders by producing antibodies or killing infected cells. DIVIDED INTO 2 LARGE CATEGORIES: NONSPECIFIC AND SPECIFIC IMMUNITY Immune System – The system in the body responsible for maintaining homeostasis by recognizing harmful from non-harmful organisms and producing an appropriate response.

Foreign Invaders Called Pathogens – Viruses, bacteria or other living thing that causes disease/immune response. Antigens – Soluble substances: Toxins & foreign proteins – Particulate: Bacteria/ tissue cell

Parts of the Immune System 1.Blood - White Blood Cells in particular 2.Bone Marrow – Produces B Lymphocytes and T lymphocytes 3.Thymus Gland – consist of T Lymphocytes (originally produced in the bone marrow) – Recognizes self from non-self – Mature and than move to spleen lymph nodes looking for invaders 4. Normal functioning: nutrition, stress, sanitation and age

Nonspecific vs. Specific Immunity Nonspecific: responds to all in the same manner Species resistance Mechanical & Chemical Barriers Inflammatory response Interferon & Complement Specific: 3 rd line defense B lymphocytes: Antibodies: Humoral T-lymphocytes: direct, cell mediated

IMMUNOLOGY : NON-SPECIFIC IMMUNITY NONSPECIFIC IMMUNITY - INCUDES SPECIES RESISTANCE, MECHANICAL/CHEMICAL BARRIERS, AND INFLAMMATION First Line of Defense – The Skin Provides Physical/mechanical and Chemical barriers Physical – hard to penetrate, made of indigestible keratin, hairs Chemical – tears, sweat, mucous, saliva, enzymes, sebum

Second Line of Defense – Inflammatory Response – When foreign invaders gain access to the body SIGNS OF INFLAMMATION: REDNESS HEAT PAIN SWELLING *cells of the invaded tissue release enzymes called mediators that attract white blood cells via chemotaxis. Blood vessels dilate and become more permeable. Specific white blood cells, usually neutrophils, begin to “gobble up” the foreign material (phagocytosis). IMMUNOLOGY: NON-SPECIFIC IMMUNITY

Nonspecific Immunity Inteferon – Substance that prevents replication of virus in the host cell Complement – Group of enzymes activated by specific & nonspecific immune system – Act on cell wall > pores in membranes > rupture/lysis of the cell

IMMUNOLOGY: SPECIFIC IMMUNE RESPONSE Third Line of Defense – Specific Immune Response – Conducted by 2 types of white blood cells called lymphocytes (B-cell And T – cell lymphoctyes)

IMMUNOLOGY: SPECIFIC IMMUNE RESPONSE This is a specific response to a specific pathogen/antigen. B-cell lymphocytes are responsible for humoral immunity, which involves the creation of Antibodies. – Clone of cells some plasma cells > Ab and others become memory cells – Long time to respond – Memory cells and Ag is presented again than it is shorter T-cell lymphocytes carry out cell-mediated immunity by directly combining with the foreign cell and destroying it or rendering it incapable of causing disease – Macrophages help present antigen – antigen presenting cells – Faster response

The Pathway of Specific Immune Response Pathogens Pathogens eaten by Macrophage Displays portion of Pathogen on surface to T cells Helper-T cell recognizes Pathogen Step 1 Step 2 Step 3

Activates B- Cell Activates Cytotoxic T- Cell Memory B-Cell Memory T-Cell Kills Infected Cells Antibodies 

Immune Response Explained 1.Antigen infects cells. 2.Macrophage ingests antigen and displays portion on its surface. 3.Helper T- Cell recognizes antigen on the surface of the macrophage,binds to it, becomes sensitized and rapidly divides. 4.Sensitized Helper T-Cell divide into Cytotoxic T-Cells, helper T- cells, suppressor T-cells, or become memory T-cells. 5.Active Cytotoxic T-Cells kill infected cells and memory T-cells wait for a second infection of the same antigen. 6.At the same time, B-Cells divide into Plasma Cells and Memory B- Cells. 7.Plasma cells produce antibodies that deactivate pathogen. 8.Memory T and Memory B cells remain in the body to speed up the response if the same antigen reappears. 9.Supressor T-Cells stop the immune response when all antigens have been destroyed.

Immune Response Summary Antigen Macrophage Helper T - Cell Active Cytotoxic T-CellActive B - Cell Kills Infected CellsPlasma CellMemory B-Cell Antibodies Deactivates Antigens Harmless/agglutinate/destruction Memory T-cell Displays copy of antigen on surface of cell Cellular Immunity Antibody Immunity

Cellular Immunity.vs. Antibody Immunity Carried out by T-Cells Infected cells are killed by Cytotoxic T –Cells. Carried out by B-cells Antibodies are produced and dumped into blood stream. Antibodies bind to antigens and deactivate them. Cellular Immunity (cell-mediated) Antibody (Humoral) Immunity

Antibodies Y-shaped protein molecule. Made up of variable and constant regions. Made up of Heavy and Light chains. Produced by B- Lymphocytes Function: Recognize antigens, bind to and deactivate them. – Note: Variable region recognizes the anitgens.

How an antibody operates/works Deactivation of a bacterium by an antibody.

Primary.vs. Secondary Immune Response Primary Immune Response – This is a response to an invader the First time the invader infects the body. No measurable immune response for first few days. Next 10 – 15 days antibody production grows steadily Secondary Immune Response – A more rapid response to an invader the 2 nd time it invades the body. Antibody production increases dramatically and in a much shorter time period..

Primary.vs. Secondary Immune Response

Development of Immunity Inherited immunity – Genetic factors that affect baby before birth E.g. giving tetanus to mothers so babies can inherit this protection via placenta Acquired immunity: resistance after birth – Natural – Artificial

Development of Immunity 1.Natural Immunity This is immunity that occurs whenever an animal is naturally exposed to a pathogen. Natural immunity can be active or passive. active: when the animal’s own immune system encounters a pathogen and mounts an immune response passive: when antibodies are given to a person or animal from the blood or colostrum from another person or animal. *this type of immunity only lasts for a short period of time. * Colostrum is major source of antibodies in young puppies 2.Artificial Immunity This is immunity where a deliberate exposure to the pathogen is created (i.e. vaccinations). An injection of a weakened strain of an infectious microbe (pathogen) causes the body to undergo an immune response. This is also an example of active immunity.

Autoimmune Disease Autoimmune diseases are diseases where the immune system begins to attack itself. – Ex: Autoimmune Hemolytic Anemia Autoimmune skin diseases Systemic Lupus Erythematosus Cause(s):unknown Cures/Treatments: No known cures. Usually treated with drugs (steroids, other immunomodulating drugs,etc).

Allergies Allergy - An exaggerated response by the immune system to an allergen. Allergen: a normally harmless substance that causes an allergic reaction. ex: dust, pollen, mould, food, insect stings Types of Allergic reactions There are two types of allergic reactions. a. Immediate – occurs within seconds and normally lasts for about 30 mins. b. Delayed – takes longer-hours to days- to react and can last for a much longer time.

What happens during an allergic reaction? During an allergic reaction antibodies cause histamines to be released from certain cells. Histamines cause: a. Swelling of tissues b. Release of fluids (runny noses and eyes) c. muscle spasms (some cases) d. vasodilation (heat) Anaphylaxis or anaphylactic shock: This is the sudden and severe allergic reaction to a substance that can cause death. Treatments for Allergies 1.Avoidance of allergen – especially food. 2.Epinephrine – “epi-pen” 3.Antihistamines -- benadryl