Bio exam 2 chapter 24

Define or describe the immune system, including the various organs, tissues, cells and other components of which it is comprised

Immune System - a system of organs, tissues, cells, and cell products that protect an organism from foreign & potentially harmful organisms, tissues or other substances. Comprised of . . . The lymphatic system (including lymph vessels & nodes; thymus, spleen, tonsils & adenoids). Bone marrow & a variety of white blood cells. Antibodies & complement proteins. A variety of signal molecules.

example of adaptive immunity

Individuals are injected with a "vaccine" (or infected with a pathogen). Vaccines are comprised of dead or attenuated pathogens (or fragments). Immune system builds up a first-time defense to the pathogen. Includes production of antibodies & specific "memory" lymphocytes. Immune system protects against future infections or attacks by the same pathogen.

role of interferons, the complement system and the inflammatory response.

Interferons Antiviral proteins produced by virus-infected cells that help to limit the cell-to-cell spread of viruses. "Interfere" with viral replication; & activate immune cells (e.g. natural killer cells and macrophages). Complement System A group of about 30 kinds of serum proteins that can act with (i.e. "complement") or help antibody & phagocyte defense mechanisms. Also help stimulate the inflammatory response. Inflammatory Response The characteristic redness, swelling, pain and heat exhibited by a tissue when it is damaged by physical or chemical agents, or by infection.

Describe the nature of innate defenses in invertebrates, including its basic components & modes of action (5)

Invertebrate Innate Immunity Includes . . . -Exoskeleton - a hard impermeable chitinous "shell" that prevents the entry of foreign microbes. -Low internal pH - that inhibits the growth of microbes. -Lysozyme - an enzyme that degrades bacterial cell walls, causing them to lyse and die. -Phagocytes - circulating immune cells that engulf and digest foreign substances. -Recognition proteins - bind to microbes & trigger the release of antimicrobial peptides.

Explain the process of antigen presentation, and how this leads to activation of helper T cells and cytotoxic T cells, including how the latter cells destroy infected body cells.

Macrophage ingests & degrades foreign cells or material, and breaks it into antigenic fragments. Self proteins bind to foreign non-self molecules/antigens. Self/non-self complexes are displayed at cell surface. Virgin helper T cells bind to self/non-self complexes (= recruitment /activation). Signal molecules stimulate division of activated Helper T cells to form memory T cells and effector T cells. Activated Helper T cells secrete Interleukin-2 which . . . Activates B cells (& the humoral response), and Cytotoxic T Cells (& the cell-mediated response). SLIDE 29 30

structure & function of lymph nodes,

Nodules of lymphatic tissue inter-spersed throughout the lymphatic system. Lymphatic fluid is "filtered" by lymph nodes where resident macrophages engulf & destroy any foreign debris and/or invaders). Lymphocytes may mount an adaptive immune response. "Swollen sensitive glands" (i.e. lymph nodes) are a sign that the body is fighting off an infection.

Describe the specific structure of an antibody and relate its structure and shape to its functions.

Structure & Function of Antibodies Y-shaped protein receptor molecules (aka Immunoglobins) produced by B cell lymphocytes. Comprised of four polypeptide chains: Two heavy + two light chains, Each with variable & constant regions. Each recognizes or binds only one specific antigen. All function to "neutralize" antigens and/or mark them for destruction via phagocytes Phagocytes recognize & bind/attach to base of "Y"

Define and distinguish between the humoral immune response and the cell-mediated immune response in adaptive immunity

The "Dual Defense" . . . ? The Humoral Immune Response Involves the production and secretion of free-floating antibodies into the bloodstream and lymphatic fluids by B Cell Lymphocytes. The Cell-mediated Immune Response. Involves T Cell Lymphocytes that . . . Attack body cells infected with bacteria or viruses. Promote phagocytosis by other white blood cells. Stimulate B Cell Lymphocytes to produce antibodies.

List and describe the various components of the lymphatic system and how they function as part of the immune system,

The lymphatic system . . . Is comprised of lymph vessels & nodes, thymus, spleen, tonsils & adenoids. Functions closely with the circulatory system. Has several important functions: Digestive Function (From before) . . . Lymphatic vessels of the small intestines (lacteals) absorb fats (lipoproteins) at the intestinal villi and transport them to the bloodstream. Circulatory Function - Lymphatic vessels absorb excess tissue fluid and return it to the bloodstream. Immune Function - Produce, maintain, & distribute lymphocytes; macrophages destroy foreign materials; help defend the body against disease.

adenoids and tonsils

They are comprised of "lymphoid" tissue (like lymph nodes), & contain lymphocytes, macrophages & antibodies. They trap, destroy & serve as a defense against ingested or inhaled bacteria & viruses. Become swollen, irritated & infected when very active. May be removed if troublesome.

following a simple wound

Tissue injury allows entry microbes. Mast cells release histamines - cause capillary dilation; attracts neutrophils. Macrophages release cytokines - promote blood flow into area. Damaged cells release prosta-glandins - stimulate local pain. Capillaries dilate, become leaky, allow fluids into tissue. Tissue swells, becomes red & warm. More neutrophils are attracted to infected area. Platelets & clotting factors bind to damaged tissue & initiate clotting. Neutrophils & macrophages phagocytize microbes & damaged cells Blood clot forms & tissue heals.

List and describe the three main ways complement proteins enhance the innate immune response.

1. Enhance Inflammation Bind to mast cells & trigger more histamine release. 2. Help Target Cells for Destruction Bind to cells coated with antibodies as extra signal 3. form membrane attack complexes

Distinguish between the two main types of immunity (innate vs. adaptive)

1. Innate Immunity Aka non-specific, genetic, or natural immunity. Involves a set of defenses that are immediately active, and independent of previous encounters with a given pathogen or substance. Are the same, whether or not the pathogen has been previously encountered. Found in both vertebrates & invertebrates. 2. Adaptive Immunity Aka acquired immunity. Involves a set of defenses developed for, and activated by specific pathogens or substances. Immune system "remembers" (or specifically recognizes) a previously encountered pathogen. Found only in the Vertebrates.

Describe the four ways that antibodies mark antigens for elimination in the humoral immune system.

1. Neutralization (blocks viral binding 2. Agglutination (of microbes) 3.Precipitation (of dissolved antigens 4.Activation of the complement system

including the similarity and difference between active vs. passive immunity, and examples of each

Active Immunity - long-term immunity that occurs when an individual produces his own supply of antibodies, either by exposure to a foreign entity or by immunization. e.g. Exposure to Chickenpox or Measles. e.g. Vaccination for Smallpox or Tetanus. Passive Immunity - temporary immunity that occurs when an individual is given previously prepared antibodies to prevent a disease. e.g. Treatments for rabies & snakebites (anti-venom). Mother's antibodies protect unborn children. Colostrum provides antibodies to breastfed infants.

Explain how our "molecular fingerprints" interacts with the immune system to identify "self" vs. "non-self" molecules or cells, the body's own "self" molecules and how this complicates (or relates to) organ transplants.

All cells of the human body display the same set of "self" proteins (aka as "MHC" proteins) that serve as a "molecular fingerprint". Humans produce about 14 "major" complexes. No two humans (except twins) produce the same sets of MHC proteins. The immune system recognizes "non-self" & mounts an attack - e.g. on organ transplants. Transplant surgeons look for donors with matching MHC proteins.

Explain how allergies and allergic reactions occur and how this can lead to anaphylactic shock.

Allergic Reactions Occur In Two Stages: Stage 1 - Sensitization - i.e. the very first exposure to an allergen - i.e. the antigen that elicits the allergen. Stage 2 - Over Reaction - i.e. over-stimulation of the inflammatory response during a later exposure to the same antigen. Can be life-threatening or fatal. Allergen enters the bloodstream. Virgin B Cells are recruited to produce antibodies. B Cells develop into plasma cells that release antibodies. Antibodies attach to mast cells Allergen enters the body a second time & binds to antibodies on mast cells. Mast cells release histamine, which triggers allergy symptoms, including the inflammatory response. Inflammation of nasal membranes results in typical allergy symptoms (runny nose, tearing eyes, sneezing). Anaphylactic Shock - an immediate & severe allergic reaction that occurs when an allergen enters the bloodstream and affects the entire body. Examples: Insect stings, medications, foods (nuts, shellfish, dairy). Main symptoms include a sudden drop in blood pressure & rapid swelling of tissues (including tissues around airways), hives, due to histamine-induced capillary permeability & release of fluids into body tissues. Main treatments include injection with adrenaline (increases blood pressure, expands airways, constricts blood vessel) and antihistamines (to counter act the massive histamine release).

and the role of the lymphatic system in draining excess tissue fluids.

Any foreign debris or microbes in the interstitial fluid are also collected by the lymphatic system where they are eventually trapped & destroyed by WBC's in the lymph nodes. Interspersed throughout the lymphatic system is a series of "check" valves that function (along with muscle contractions) much like in veins slide 14

Describe how some disorders of the immune system (e.g. autoimmune diseases, Immunodeficiency diseases & allergies), including some common specific examples, can affect human health.

Autoimmune Diseases - the immune system fails to distinguish between foreign antigens and "self" antigens; Cytotoxic T cells & antibodies attack the bodies own cells. Immunodeficiency Diseases (besides AIDS) where an immune response is defective or absent. Allergies - fast, hypersensitive, overreactions of the immune system to normally harmless antigens.

Define or describe helper T cells, including their specific functions and interactions with (or activation) of other cells.

Background on Helper T Cells . . . T Cell Lymphocytes that trigger humoral & cell-mediated immune response. They must first be "activated" (or "recruited) into action - i.e. "naïve" or "virgin" cells must encounter their first antigen. Involves complex self/antigen receptors. First exposure to antigen only occurs via macrophage "antigen presenting cells". Antigen-Presenting cells include: Macrophages & B cells. Activated Helper T Cells then activate . . . B cell lymphocytes (Humoral Response). Cytotoxic T Cells (Cell-mediated response).

including the development, recruitment and functions of B lymphocytes vs. T lymphocytes.

Both originate in bone marrow from stem cells. B cells mature in marrow. T cells mature in thymus. Genes for antigen receptors are "scrambled". Each cell can produce only one type of antigen receptor. Millions of "receptor unique" cells take residence in the lymphatic system. Each cell can bind only one type of antigen. Mature B Cells & T Cells are transported to lymphatic organs (e.g. nodes, spleen, tonsils) & "wait until recruited". Recruitment = first antigen recognition - cell division is activated; many more cells are produced. Humoral Response - B cells release antibodies that tag (mark) antigens in body fluids for destruction. Cell-mediated Response - T cells actively engage & destroy infected cells of the body.

Describe the nature of antigens, epitopes (antigenic determinants) and antibodies, including how an antigen and an antibody interact.

Characteristics of Antigens: They are molecules (or parts of molecules) that elicit the adaptive immune response. They usually do not belong to the host animal. They are typically proteins or large polysaccharides on the surfaces of viruses or foreign cells. Epitopes - (aka antigenic determinants) - specific regions on an antigen where antibodies bind. An antigen usually has several different epitopes. The antigen-binding site of an antibody and an antigenic determinant have complementary shapes Structure & Function of Antibodies Y-shaped protein receptor molecules (aka Immunoglobins) produced by B cell lymphocytes. Comprised of four polypeptide chains: Two heavy + two light chains, Each with variable & constant regions. Each recognizes or binds only one specific antigen. All function to "neutralize" antigens and/or mark them for

Describe the process of clonal selection (recruitment), and compare a primary immune response to a secondary immune response

Clonal Selection (aka clonal recruitment): The process whereby genetically unique (naïve or virgin) lymphocytes react with (recognize) their specific antigen for the very first time. Stimulates their mitotic proliferation. Clonal Selection (aka clonal recruitment): Stimulates their mitotic proliferation. Leads to the production of Effector B Cells (aka Plasma Cells) and Memory Cells. Effector/Plasma cells produce & secrete massive amounts of antibodies (2000/sec). Memory Cells migrate to lymph nodes to respond to subsequent invasions. Last for decades. Activated by Helper T cells. Macrophages destroy antigens bound to antibodies. Also involved in "antigen presentation". slide 24

Describe how vertebrate innate immunity functions as a first and second line of defense

First Line of Defense - Barriers to Entry: Skin - dead, keratinized cells form an impermeable barrier. Mucous membranes - form a sticky trap for microbes; ciliated cells sweep mucus & microbes into throat. Second Line of Defense (if above fails) - Innate Immune Cells: Neutrophils - "first-responder" phagocytes circulate freely in blood; are attracted to infection sites; squeeze between cells of capillary wall. Macrophages - "large" phagocytes that reside in, & wander through the interstitial fluids. Natural Killer Cells - attack cancer cells and virus-infected cells.

Describe some of the things that can cause the in inflammatory response, the steps of the inflammatory response in relation to a simple wound

From before . . . The characteristic redness, swelling, pain and heat exhibited by a tissue when it is damaged by physical or chemical agents, or by infection. Inflammation (i.e. the inflammatory response) is mediated by changes in capillaries in the damaged area. Can be localized or widespread. Is sometimes accompanied by fever. Triggers a co-localized innate immune response.

Describe the nature and characteristics of adaptive immune system responses,

General Characteristics of Adaptive Immunity Only found in the Vertebrates. A second line of defense - when innate (non-specific) immune response fails to ward off a pathogen. Slower than innate defenses - i.e. normally takes 5 - 7 days to mount a response). Highly specific - involves the recognition of foreign cells, particles & molecules (i.e. "antigens") as "non-self" by the immune system. Recognition is mediated by antibodies. Can "remember" antigens or pathogens that have been encountered before. Involves B Cell & T Cell Lymphocytes. Often referred to as "acquired immunity".

Explain which cells are infected by HIV and how this leads to acquired immunodeficiency disease (i.e. AIDS).

Helper T cells are recruited & activated when they bind to self/non-self complexes on antigen-presenting cells. Activation of helper T cells leads to the activation of B cells (the humoral response) as well as Cytotoxic T Cells. HIV attacks HTC's, leading to diminished immune response to other subsequent new or previous infections. Individuals die from infections that are normally resisted by a healthy immune system