Chapter 21 IMMUNE SYSTEM - Quia

Chapter 21IMMUNE SYSTEMCopyright 2022 Elsevier Inc. All rights reserved.1

Lesson 21.1: Immune System1. Discuss nonspecific immunity, includingthe following:2. Discuss specific immunity, including thefollowing: Describe the process of phagocytosis. Explain the causes of the signs ofinflammation.Differentiate between specific andnonspecific immunity. Explain the role of fever in fightinginfection.Explain the role of T cells in cellmediated immunity. Explain the role of B cells in antibodymediated immunity. Explain the role of interferons,complement proteins, and naturalkiller cells in the defense of the body.3. Differentiate between geneticimmunity and acquired immunity.4. Describe naturally and artificiallyacquired active and passive immunity.5. Describe other immune responses,including the following:Copyright 2022 Elsevier Inc. All rights reserved. Identify the steps in the developmentof anaphylaxis. Define autoimmunity.2

Classification of the Immune System:NonspecificNonspecific immunity (innate Protects the body againstmany different types offoreign agents Enables the body to respondeven when it does notrecognize the specific foreignagentInnate immunity: certaindefense mechanisms that donot require prior exposure tothe pathogen or foreignagent. First line of defense: Mechanical barriers Intact skin and mucousmembranesChemical barriers Second line of defense: Phagocytosis: Engulfs, Eating of pathogens or cellulardebris.immunity): Acid mantle, stomachsecretions, saliva, sweat, andenzymesSneezing, coughing,vomiting, diarrheaNeutrophils and Monocytes Phagocytes travel through the blood to the site ofinfection, neutrophils and monocytes can squeezethrough tiny gaps between the endothelial cells ofthe capillary wall and enter the tissue space at thesite of the infection. Diapedesis process of squeezing through the tiny gaps. Chemotaxis chemicals released by injured cellsattract them to the injured site.Inflammation: Body response on being confronted by anirritant. Infection Irritant is caused by a pathogen, theinflammation is called Infection. Classical signs of inflammation: Redness, heat,swelling, and painFever (Pyrexia): Reflexes Pyrogens Phagocytes perform their duty andrelease fever producing substances.Protective proteins Interferons: group of proteins secreted by cellsinfected by a virus complement proteins: circulate in the blood intheir inactive form., when activated against abacterium, they swarm over it.Natural killer (NK) cells Special type of lymphocyte that kills a variety ofcellsPage 394, Fig. 21.1. Nonspecific Immunity.First line of defense: mechanical barriers, chemicalbarriers, and reflexes.Second line of defense: phagocytosis, inflammation,fever, protective proteins, and natural killer (NK) cells.Look at Table 21.1 on Page385.3Copyright 2022 Elsevier Inc. All rights reserved.

Classification of the ImmuneSystem: Specific Specific immunity Hones in on a specific substanceSpecific immunity (also called adaptive immunity):cause the immune cells can respond or adapt to newlyencountered pathogens or foreign agents.1.Specificity homes in on a foreign substance (measlesvirus or ragweed pollen). Provides protection against onespecific substance but not others.2.Memory ability to respond faster and more robustly toreexposure to the same pathogen or foreign agent. Third line of defense AntigensoSubstance that stimulates the formation of antibodiesoImmunotoleranceLymphocytesoT lymphocytes (T cells)oB lymphocytes (B cells)Macrophages4Page 388, Fig. 21.2. The Immune System Wages Its Battle with ThreeLines of Defense. (Read from bottom to top.)Copyright 2022 Elsevier Inc. All rights reserved.

Classification of the Immune System: T-cell and B-cell Page 390, Fig. 21.3.Cell-Mediated Immunity.Steps in cytotoxic T-cellactivation and production ofa clone of cytotoxic T cellsand memory T cells. B-cell activation and antibodymediated immunity Step 1: The B cell originatesand matures in the red bonemarrow; it then seeds otherlymphatic tissue where iteventually encounters anantigen. Step 2: antigen presentation Step 3: B-cell and helper T-cell(CD4 T cell) activation Step 4: production of a cloneT-cell activation and cell-mediatedimmunity Step 1: T cells originate in the red bonemarrow and migrate to the thymusgland, where they mature; they thenseed other lymphatic tissue, where theyeventually encounter an antigen. Step 2: antigen presentation Step 3: T-cell activation Step 4: production of a clonePage 391, Fig. 21.4. Antibody-mediated Immunity.Steps in B-cell activation and production of a cloneof antibody-secreting plasma cells and memory B 5cells.Copyright 2022 Elsevier Inc. All rights reserved.

Copyright 2022 Elsevier Inc. All rightsreserved.Classification of the Immune System: Antibodies: Antibodies are secreted by the B cellsare proteins called immunoglobulinsand constitute the gamma globulinfraction of plasma proteins. Immunoglobulins: antibodiessecreted by the B cells1.2.Immunoglobulin G (IgG) antibody found in plasma and tissuefluids. Effective against certainbacteria, viruses, and toxins. What antibodies do: 3.Immunoglobulin M (IgM) 4.Immunoglobulin D (IgD) 5.Immunoglobulin E (IgE) antibody Directly by attacking the antigen and indirectly by activatingcomplement proteins that in turn facilitate the attack on theantigens. Indirectly by activating complement proteins that in turnfacilitate the attack on the antigens Primary response: due to initial exposure to the antigen,develops slowly and produces a small number ofantibodies. Secondary response:Immunoglobulin A (IgA) antibodyprimarily in the secretions of exocrineglands. IgA in milk, tears, and gastricjuice helps protect infection. BreastMilk contains IgA and helps infantward off infection.Antibodies destroy antigens. Memory cells are activated very quickly on second exposureand induce the formation of many antibody-secreting plasmacellsAntibody titer Level of antibodies in the bloodPage 392,Fig. 21.5.Primary and Secondary Responses to an Antigen.antibody found in blood plasma. AntiA and Anti-B antibodies with red bloodcells are a type of IgM antibody.antibody found on the surface of Bcells and participates in theactivation of B cells.appears in the exocrine secretions,such as breast milk, tears, GIsecretions, and urine. IgE participatesin allergic reactions .6

Types of Immunity Genetic Immunity: (also known as Inborn, innate, or speciesimmunity) Inherited immunity to certain diseases, born with geneticinformation that provides immunity to certain diseases.Acquired Immunity: Received during a person’s lifetime, achieved naturally orartificially. Naturally Acquired Immunity: Own body produced antibodies (also called active immunity- generally long lasting). One way to have Naturally Acquired Immunity: First getting the disease and then your body responded to the specificpathogen by developing antibodies.Second way to have Naturally Acquired Immunity: Receiving antibodies from your mother, some antibodies IgG crossed theplacenta from your mother to the fetus. Your mother developed these antibodies in her lifetime, Because yourimmune system did not produce antibodies, you received them from yourmother called PASSIVE IMMUNITY.Artificially acquired immunity: Vaccine antigen-bearing substance, such as a pathogen, injected intoa person in an attempt to stimulate antibody production. Attenuated virus CAN NOT cause the disease when injected n to the person,but it can still act as antigen and stimulate persons immune system toproduce antibodies.Injection of Immune globulin: obtained by from a donor (human oranimal) and contains antibodies (immune globulins). Antibodies formed in the donor in response to a specific antigen , thepreformed antibodies are taken from the donor and injected in to therecipient, thereby conveying Passive Immunity.Page 393, Fig.21.6. Types of Immunity.Look at table 21.2 on page 395.7Copyright 2022 Elsevier Inc. All rights reserved.

Altered Immune Response Autoimmune disease: The body Immediate Hypersensitivity Reactionattacks itself, overreacts, causingallergies, or it fails to act when it Anaphylaxis or anaphylactic shockshould respond (Immunodeficiency). Examples: Rheumatoid Arthritis,Diabetes mellitus (Type 1),Rheumatic fever, Lupus, Thyroiditis.Allergies – Immune system formsantibodies to substances not usuallyrecognized as foreign, allergicreactions. Delayed-reaction allergy Usually takes about 48 hours, onset isdelayed Usually results from repeatedexposure of the skin to chemicals Contact dermatitis-activation of Tcells, which accumulate in the skinImmediate-reaction allergy Immediate hypersensitivity reactioninvolves immunoglobulin Ex. Insect Venom, drugs such aspenicillin, and foods such as peanuts Allergens- Antigens capable ofinducing allergy Severe form of the immediatehypersensitivity reactionSystemic effectsTx. Epinephrine (adrenalin)Immunodeficiency disorders: Primary Immunodeficiency Disorders:RARE, EX. SCID (Severe CombinedImmunodeficiency disorders) Secondary Immunodeficiency Disorders:Common, being a drug induced immunedeficiency, such as the granulocytopeniaresulting from cancer chemotherapy. Other causes: radiation therapy,steroid therapy, stress, malignancies,aging, and many diseases, especiallyinfection with the humanPage395, Fig.21.7.8immunodeficiency virus (HIV)Immediate Hypersensitivity Reaction.Copyright 2022 Elsevier Inc. All rights reserved.

immunity) Inherited immunity to certain diseases, born with genetic information that provides immunity to certain diseases. Acquired Immunity: Received during a person's lifetime, achieved naturally or artificially. Naturally Acquired Immunity: Own body produced antibodies ( also called active immunity- generally long lasting).