1. CHAPTER 3: Adaptive Immunity (specific body defense system)

2.  Immunity: refers to the ability of an organism to recognize and defend itself against infectious agents  Susceptibility: opposite of immunity, is the vulnerability of the host to harm by infectious agents  Immunology: the study of adaptive immunity and how the immune system responds to specific infectious agents and toxins  Immune system: consists of various cells, especially lymphocytes, and organs such as the thymus gland, that help provide the host with specific immunity to infectious agents

3.  Innate immunity (genetic): exists because of genetically determined characteristics  All humans have immunity to many infectious agents that cause disease in pets and domestic animals  Adaptive immunity (acquired): immunity obtained in some manner other than heredity  Naturally acquired adaptive immunity is most often obtained by having a specific disease  Artificially acquired adaptive immunity is obtained by receiving an antigen by injection of vaccine or immune serum

5. Formed cellular elements of the blood

8. The Bursa of Fabricus In chickens this is where B cells develop

9.  B-lymphocyte- B cell Humoral immunity (antibodies)  T-Lymphocyte-T cell Involved cell mediated All distributed to the entire body by, Peyers path and nodule in digestive trace, Spleen, lymph nodes, blood and thymus

10.  Lymphocytes give rise to two major types of immune responses 1. Humoral immunity: carried out by antibodies circulating in the blood 2. Cell mediated immunity: carried out by T cells and occurs at the cellular level

11.  Specific immune responses are carried out by lymphocytes which develop from stem cells as do other white blood cells, red blood cells, and platelets  B lymphocytes (B cells): lymphocytes are processed and mature in tissue, referred to as bursal-equivalent tissue  T lymphocytes ( T cells): stem cells migrate to the thymus, where they undergo differentiation into thymus-derived cells

12. Definition-A network of conduits(vessels) carry a clear fluid called lymph.Travel only one way flow towards the heart. The lymphatic system can be broadly divided into the conducting system and the lymphoid tissue.  The conducting system carries the lymph and consists of tubular vessels that include the lymph capillaries, the lymph vessels, and the right and left thoracic ducts.lymph capillarieslymph vesselsrightthoracic  The lymphoid tissue is primarily involved in immune responses and consists of lymphocytes and other white blood cellslymphocyteswhite blood cells  Regions of the lymphoid tissue densely packed with lymphocytes are known as lymphoid follicles.  Lymphoid tissue- either structurally well organized as lymph nodes or loosely organized lymphoid follicles known as the mucosa-associated lymphoid tissue (MALT) mucosa-associated lymphoid tissue (MALT)

13.  Lymp (contain plasma cell and excess fluid between spaces cell)  Flow in lymph capillaries->lymph vessel ->passes through lymph nodes->return to venous blood by lymphatic duct (right or left)  Movement of lymph is by mechanical contraction of skeleton muscle.

14. tonsil Thymus gland spleen Lymph nodes Lymphatic vessel

15. it is responsible for the removal of interstitial fluid from tissues it absorbs and transports fatty acids and fats as chyle to the circulatory systemfatty acidsfatschyle it transports immune cells to and from the lymph nodes in to the bone The lymph transports antigen-presenting cells (APCs), such as dendritic cells, to the lymph nodes where an immune response is stimulated.antigen-presenting cells The lymph also carries lymphocytes from the efferent lymphatics exiting the lymph nodes FUNCTION OF LYMPHATIC SYSTEM

16. Including,  primary lymphoid organ-thymus and bone marrow Function- production and selection of lymphocytes  Secondary lymphoid organ- lymph nodes, and the lymphoid follicles in tonsils, Peyer's patches, spleen, adenoids, skin lymph nodestonsilsPeyer's patchesspleen adenoidsskin Function - maintain mature naive lymphocytes and initiate an adaptive immune response environment for the foreign or altered native molecules (antigens) to interact with the lymphocytesantigens

18.  Y-shaped protein molecules composed of four polypeptide chains – two identical light (L) chains and two identical heavy (H) chains  Constant regions: determines the particular class that an immunoglobulin belongs to  Variable regions: each chain have a particular shape and charge that enable the molecule to bind a particular antigen

21.  Five classes of immunoglobulins have been identified in humans and other higher vertebrates 1. IgG: the main class of antibodies found in the blood accounts for as much as 20% of all plasma proteins 2. IgA: occurs in small amounts in blood and in larger amounts in body secretions (tears, milk, saliva and mucus) 3. IgM: found as a monomer on the surface of B cells and is secreted as a pentamer by plasma cells 4. IgE: has a special affinity for receptors on the plasma membranes of basophils in blood or mast cells in tissues 5. IgD: found mainly on B-cell membranes and is rarely secreted

22. The Structures of the Different Classes of Antibodies

23.  IgA  IgM  IgE  IgG  IgD

24.  In humoral immunity the primary response to an antigen occurs when the antigen is first recognized by host B cells  Primary response of B cells can occur by two mechanisms: 1. B cells can be activated by binding antigen, proliferating and forming plasma cells (T-independent antigens) 2. Produces IgM antibody and no B memory cells are formed (T-dependent antigens)  Secondary response: when an antigen recognized by memory cells enters the blood

26. Primary and Secondary Responses to an Antigen

27. Produces IgM antibody and no B memory cells are formed (T-dependent antigens)

28. Primary and Secondary Responses to an Antigen

29. Antibodies produced by humoral immune responses eliminate foreign agents in three ways: 1.Neutralization 2.Opsonization 3.Immune complexes

30. Summary of Humoral Immunity

31.  Involves the direct actions of T cells  T cells interact directly with other cells that display foreign antigens  Involves the differentiation and actions of different types of t cells and production of chemical mediators (cytokines)  Cytokines: lymphokines and interleukins

32. Types of T cells: After T cells are challenged by antigens, the cells differentiate into one of several types of functioning T cells

33.  Involves the response of T lymphocytes  T cells cannot be activated directly by antigens  Macrophages that have processed an antigen secrete the lymphokine interleukin-1 (IL-1), which activates T helper cells  T helper cells secrete interleukin-2 (IL-2) and activate delayed hypersensitivity cells and cytotoxic killer cells  IL-1 and IL-2 cause undifferentiated cells to become natural killer cells

34. The Reactions in Cell-Mediated Immunity

36. Summary of Cell-mediated Immunity: “CD” stands for cluster of differentiation