Inquiry into LifeTwelfth Edition

Chapter 13

Lecture PowerPoint to accompany

Sylvia S. Mader

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

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 out-

compete 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 non-infected 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 antigen is present on red blood cells– Rh- 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 anti-

Rh 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)