Chapter 13

July 23, 2018 | Author: Anonymous | Category: N/A
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Inquiry into Life Twelfth Edition

Sylvia S. Mader Chapter 13

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13.1 The Lymphatic System • The Lymphatic System – Lymphatic Vessels – Lymphatic Organs

• The Lymphatic System Contributes to Homeostasis – Returning excess tissue fluid to the bloodstream – Absorbing fat from the digestive tract and transports them to the bloodstream – Helps defend the body against disease

Lymphatic System

13.1 Lymphatic System • Lymphatic Vessels – A one-way system – Fluid inside is called lymph • Consists of water and solutes

– Lymphatic capillaries • • • •

Found in most areas of the body Small, closed-ended vessels Capillaries merge into larger vessels These larger vessels carry the lymph into the thoracic and lymphatic ducts • Lymph is returned to the bloodstream

13.1 Lymphatic System • Lymphatic Vessels Continued – Larger Lymphatic Vessels • Valves prevent backflow • Movement of lymph is dependent on skeletal muscle contractions

– Edema • Localized swelling caused by accumulation of fluids in the tissues (not drained by the lymphatic system)

13.1 Lymphatic System • Lymphatic Organs – Contain a large number of lymphocytes, a

type of white blood cells • B lymphocytes (B cells) • T lymphocytes (T cells)

The Lymphatic Organs

13.1 Lymphatic System • Primary Lymphatic Organs – Red Bone Marrow • Site of blood cell production • B-cells mature in the bone marrow

– Thymus Gland • Site of T-cell maturation

13.1 Lymphatic System • Secondary Lymphatic Organs – Spleen • Cleanses the blood

– Lymph nodes • Cleanses lymph

13.2 Innate and Acquired Immunity • Innate immunity mechanisms are fully functional without previous exposure to a unwanted substance. • Acquired immunity is dependent upon exposure to specific antigens.

• Antigen: Any molecule that stimulates an immune response.

13.2 Innate and Acquired Immunity • Innate Immunity – Physical and Chemical Barriers – Inflammation

– Phagocytes and Natural Killer Cells – Protective Proteins

13.2 Innate and Acquired Immunity • Innate Immunity – Physical and Chemical Barriers • Skin and mucous membranes serve as protective barriers • Upper respiratory tract has cilia to remove trapped particles • Oil glands (skin) secretes chemicals harmful to some bacteria • Stomach is acidic • Bacteria (normal flora) in the intestines and other areas outcompete potential pathogens

13.2 Innate and Acquired Immunity • Innate Immunity – Inflammation

13.2 Innate and Acquired Immunity • Innate Immunity – Phagocytes • Phagocytes engulf pathogens via endocytosis – Neutrophils – Monocytes / Macrophages

– Natural Killer Cells • Destroy some virus-infected cells and cancer cells by cell-to-cell contact

13.2 Innate and Acquired Immunity • Complement System – Cause holes to form in the outer surface of some bacteria and viruses

• Interferons – Proteins produced by cells infected with a virus that protects noninfected cells

13.2 Innate and Acquired Immunity • Acquired Immunity – These defenses are specific against an antigen, they may take 5 to 7 days to become fully activated – Depends upon lymphocytes • B-cells • T-cells

13.2 Innate and Acquired Immunity • B cells and Antibody-Mediated Immunity • Characteristics of B Cells – Antibody-mediated immunity against pathogens – Produced and mature in bone marrow – Reside in lymph nodes and spleen, circulate in blood and lymph – Directly recognize antigen and then undergo clonal selection – Clonal expansion produces antibody-secreting plasma cells as well as memory B-cells

Clonal Selection Theory as it Applies to B-Cells

13.2 Innate and Acquired Immunity • Structure of an Antibody – Antibodies are also called immunoglobulins (Ig’s). – Y-shaped • Constant regions • Variable regions

Classes of Antibodies

13.2 Innate and Acquired Immunity • T cells and Cell-Mediated Immunity – A macrophage presents a portion of an antigen to T cells – Types of T-cells • Helper T-cells • Cytotoxic T-cells

Clonal Selection Model as it Applies to T cells

13.2 Innate and Acquired Immunity • Characteristics of T-Cells – Cell-mediated immunity against virus infected cells and cancer cells – Produced in bone marrow, mature in thymus – Antigen must be presented in groove of an MHC molecule – Cytotoxic T cells destroy nonself protein-bearing cells – Helper T cells secrete cytokines that control the immune response

Cell-Mediated Immunity

13.3 Induced Immunity • Active Immunity – Develops naturally after a person is infected with an antigen – A person produces an immune response against an antigen – Can be induced by use of vaccines – Is dependent upon the presence of Memory B Cells and Memory T Cells in the body

13.3 Induced Immunity

• Vaccines are pathogens or their products that have been treated so they are no longer able to cause disease.

13.3 Induced Immunity

13.3 Induced Immunity • Passive Immunity – An individual is given prepared antibodies to combat disease – Is temporary because there are no memory cells

13.3 Induced Immunity • Immune Therapies – Cytokines and Immunity • Signaling molecules produced by T lymphocytes and macrophages • Interleukins – Cytokines that enhance ability of T cells to fight cancer – Have many potential uses in medicine

13.3 Induced Immunity • Monoclonal Antibodies – Group of plasma cells from the same B cell all produce same antibody – Use of monoclonal antibodies • Diagnostic tests – Ex: pregnancy tests

• Vehicles for drug delivery • Identification of infections

13.4 Adverse Effects of Immune Responses • Allergies – Hypersensitivities to Substances – Immediate Allergic Response • Can occur within seconds of exposure to an antigen • IgE antibodies attach to mast cells • Allergen attaches to IgE , causing mast cells to release histamine • Histamine is responsible for allergy symptoms

– Anaphylactic Shock • Immediate allergic response where allergen enters the blood stream • Histamine causes a sudden, life-threatening drop in blood pressure • Epinephrine can counteract this reaction

13.4 Adverse Effects of Immune Responses • Blood-Type Reactions – In the ABO system, the presence or absence of type A and type B antigens on red blood cells determines a persons blood type. – If antibodies are present against a type of blood, agglutination occurs – Transfusions • Must consider recipient’s antibodies and donor’s antigens to prevent agglutination and transfusion reaction • Type O is universal donor – Neither anti-A nor anti-B antibodies

• Type AB is universal recipient – Neither A nor B antigens

13.4 Adverse Effects of Immune Responses

Blood Transfusions

13.4 Adverse Effects of Immune Responses • Rh System – Rh+ – Rh-

Rh antigen is present on red blood cells Rh antigen is absent on red blood cells

– Significant in Pregnancy • If a Rh- mother is pregnant with Rh+ baby • If baby’s cells leak into mother’s bloodstream, she forms antiRh antibodies – Attack baby’s RBC’s- hemolytic disease of newborn (HDN)

– This can be prevented by giving the Rh- mother anti-Rh immunoglobulins in an injection – The injection must be given before the mother becomes sensitized to produce her own antibodies

Hemolytic Disease of the Newborn

13.5 Disorders of the Immune System • Autoimmune Disease – Cytotoxic T-cells or antibodies attack a person’s own cells • Myasthenia gravis - muscle weakness • Multiple sclerosis - neuromuscular disorder

• Immune Deficiencies – Immune system is unable to protect the body from disease • Acquired immune deficiency syndrome • Severe combined immunodeficiency syndrome (inherited)

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