The Lymphatic and Immune Systems

The Lymphatic System Consists of two parts

Lymphatic vessels Lymphoid tissues and

organs

Lymphatic system functions Transports escaped

fluids back to the _____________

Plays essential roles in body defense and resistance to disease

Also has a role in digestion

Bukar AlibeBLOOD

Developmental Aspects of the Lymphatic System and Body Defenses

Except for thymus and spleen, the lymphoid organs are poorly developed before birth

A newborn has no functioning lymphocytes at birth, only passive immunity from the _____________

If lymphatics are removed or lost, severe edema results, but vessels may grow back in time

Bukar AlibeMOTHER

Central Lymphoid Tissue Bone Marrow + Thymus = Central Lymphoid Tissue Bone marrow

Hematopoietic stem cells: precursor for all blood cells Leukocytes except T lymphocytes fully develop here

_____________ T lymphocytes migrate from bone marrow to thymus Develop maturity in thymus

Bukar AlibeTHYMUS

Peripheral Lymphoid Tissue Spleen, lymph nodes, tonsils, adenoid, appendix, Peyers patches Collections of B cells, T cells, and _____________ Function to trap microorganisms and foreign particles Works to expose them to leukocytes in high concentrations Spleen and lymph nodes filter blood and lymph

Bukar AlibeMACROPHAGES

Lymphoid Organs That Contribute to Lymphatic Function

Spleen Located on the left side of the abdomen Filters blood and destroys worn out blood cells Forms blood cells in the fetus Acts as a blood reservoir

Thymus Located low in the throat, overlying the heart Functions at peak levels only during childhood Produces hormones (like thymosin) to program

lymphocytes Tonsils

Masses of lymphoid tissue around the pharynx Trap and remove bacteria and other foreign

materials Tonsillitis is caused by congestion with

bacteria Peyers patches

Found in the wall of the small intestine & capture and destroy bacteria in the intestine

Lymph Nodes Filters lymph (fluid) before it is

returned to the blood Defense cells within lymph nodes

Macrophages engulf and destroy foreign substances

Lymphocytes provide immune response to antigens

Some harmful materials that may enter lymph vessels Bacteria Viruses Cancer cells Cell debris Protists Worms Fungi

Lymph Node Structure Most are kidney-shaped and less than 1 inch long _____________

The outer part Contains follicles that house collections of

lymphocytes Medulla

The inner part Contains phagocytic

macrophages

Bukar AlibeCORTEX

Lymphatic Characteristics Lymph fluid carried by lymphatic vessels Properties of lymphatic vessels One way system toward the heart No _____________ Lymph moves toward the heart Squeezing motion of skeletal muscle Rhythmic contraction of smooth muscle

in vessel walls

Elephantiasis/filariasis

For a 70 kg man, total body water = 42 liters

28 liters intracellular fluid (ICF)

14 liters ___________ fluid (ECF) 3 liters plasma 11 liters interstitial

fluid (ISF)

Body Fluid Compartments

Bukar AlibeEXTRACELLULAR

Flow of Lymph Through Nodes: Lymphatic Vessels

Lymph enters the convex side through afferent lymphatic vessels Lymph flows through a

number of sinuses inside the _____________ Lymph exits through

efferent lymphatic vessels Fewer efferent than

afferent vessels causes flow to be slowed

Bukar AlibeNODE

Lymphatic Vessels Lymph capillaries

Walls overlap to form flap-like minivalves

Fluid leaks into lymph capillaries

Capillaries are anchored to connective tissue by

_____________ Higher pressure on the

inside closes minivalves Fluid is forced along the

vessel

Bukar AlibeFILAMENTS

Lymphatic Vessels Lymphatic collecting

vessels Collect lymph from

lymph capillaries Carry lymph to and

away from lymph nodes

Return fluid to circulatory veins near the heart Right lymphatic duct _____________

Bukar Alibethoracic duct

The Immune System

Body Defenses: The Immune System The body is constantly in contact with protists, bacteria, fungi,

parasitic worms and viruses (many want to live in or on you!) The body has two defense systems for foreign materials

1) Innate defense system (_____________ defense system) Mechanisms protect against a variety of invaders Responds immediately to protect body from foreign materials

2)Adaptive defense system (specific defense system) is specific defense is required for each type of invader

We can develop immunity or specific resistance to certain pathogens

Bukar AlibeNONSPECIFIC

Innate (Nonspecific) Body Defenses First Line of Defense

Physical Barriers Skin is a physical barrier to foreign

materials Mucous membranes Mucus traps microogranisms in digestive

and respiratory pathways Chemical Barriers

Secretions from sebaceous and sweat glands (salty sweat), sebum is toxic to bacteria

Sebaceous glands secrete oily substance into hair follicles

_____________ Vaginal secretions are acidic pH of the skin is acidic to inhibit bacterial

growth Stomach mucosa and secretes hydrochloric

acid, also has protein-digesting enzymes Lysozyme in tears, sweat, saliva, etc can

break down bacteria

Bukar AlibeURINE

Innate (Nonspecific) Body Defenses First Line of Defense

Nonspecific Immune Systems General Response: Flu-like Symptoms

Fever Runny nose and watery eyes Fluid and mucus in lungs Diarrhea _____________ Achy muscles Fatigue

Bukar AlibeRASH

Innate (Nonspecific) Body Defenses Second Line of Defense

Fever Abnormally high body temperature Hypothalamus heat regulation can be reset by pyrogens

(secreted by white blood cells) A _____________is substance than can cause fever High temperatures inhibit the release of iron and zinc from

the liver and spleen needed by bacteria Fever also increases the speed of tissue repair What is the normal body temperature?

Heat increases the density of sticky molecules on the surface of blood vessels in the lymph nodes, which catch more white blood cells as the blood rushes past

Bukar AlibePYROGEN

Innate (Nonspecific) Body Defenses Second Line of Defense: Phagocytosis

Phagocytosis is a process Neutrophils move by diapedesis (movement of blood cells

through capillary walls) to clean up damaged tissue and/or _____________ Monocytes become macrophages and complete disposal of

cell debris Phagocytes are a cell type

Cells such as neutrophils and macrophages engulf foreign material into a vacuole Enzymes from lysosomes digest the material

Bukar AlibePATHOGENS

Innate (Nonspecific) Body Defenses Second Line of Defense: Natural Killer Cells Natural killer (NK) cells Can ________(disintegrate or

dissolve) and kill cancer cells Can destroy virus-infected cells

Innate (Nonspecific) Body Defenses Second Line of Defense: Inflammation

Functions of the inflammatory response Prevents spread of damaging agents Disposes of cell debris and pathogens through phagocytosis Sets the stage for repair

Inflammatory response Triggered when body tissues are injured Series of events causing accumulation of proteins, fluid, and

phagocytes in area injured or invaded Four most common indicators of acute inflammation

Redness _______ Swelling Pain

Results in a chain of events leading to protection and healing

Bukar AlibeHEAT

Flowchart of Inflammatory Events

Innate (Nonspecific) Body Defenses Second Line of Defense: Antimicrobial Proteins Antimicrobial proteins

Attack microorganisms Hinder reproduction of microorganisms

Most important antimicrobial proteins Complement proteins

Uses a MAC (membrane attack complex) proteins to lyse cells May be part of the specific (adaptive) or nonspecific (innate)

immune response _____________

Proteins secreted by virus-infected cells Bind to healthy cell surfaces to interfere with the ability of viruses to multiply

Bukar AlibeINTERFERON

Second Line of Defense: Complement System Plasma proteins that lyse foreign cells, especially

bacteria Response involves ~30 proteins in cascade resulting in MAC on surface

of bacteria MAC pierces bacterial membrane causing lysis Triggers histamine release from mast cell May act as opsonins (working with antibodies) _____________ Pathway Binding to carbohydrates on bacterial cell walls Part of nonspecific defense mechanisms

Classical Pathway Binding to antibodies attached to bacteria Part of specific defense mechanisms

Bukar AlibeALTERNATE

Summary of Nonspecific Body Defenses Second Line of Defense

Specific (Adaptive) Immune Responses Third Line of Defense

Specific immune responses triggered by foreign matter

reaching lymphoid tissue Antibodies are proteins that protect from pathogens Aspects of adaptive defense

1) Antigen specific, recognizes and acts against particular foreign substances

2) Systemic, not restricted to the initial infection site 3) _____________, recognizes and mounts a stronger

attack on previously encountered pathogens 4) Can recognize self from non-self

Bukar AlibeMEMORY

Specific (Adaptive) Immune Responses Third Line of Defense

Types of Immunity Humoral immunity is antibody-mediated

immunity is B cell mediated Provided by antibodies present in body fluids Involves secretion of antibodies by plasma cells

Defend against bacteria, toxins, viruses in body fluids

_____________ immunity is T cell-mediated immunity

Targets virus-infected cells, cancer cells, and cells of foreign grafts

Involves lysis of cells by cytotoxic T cells Defend against bacteria, viruses in body cells Part of reaction to transplants and cancer cell

Bukar AlibeCELLULAR

Specific (Adaptive) Immune Responses Third Line of Defense

Specific (Adaptive) Immune Responses Third Line of Defense

Antigens (nonself) are very specific Any substance capable of exciting the immune system and provoking

an immune response Antigens (antibody generators) confer specificity

Complex proteins/polysaccharides Part of foreign invader, _____________ cell Epitopes = recognition sites on pathogen/antigen

for B or T cells B cell and T cell specificity

Antigen receptors recognize certain antigens only B cells membrane antibodies T cells T cell receptors

_____________ Human cells have many surface proteins Our immune cells do not attack our own proteins Our cells in another persons body can trigger an immune response

because they are foreign and restricts donors for transplants

Bukar AlibeTUMOR

Bukar AlibeSELF-ANTIGENS

Specific (Adaptive) Immune Responses Third Line of Defense

Immunocompetentcell becomes capable of responding to a specific antigen by binding to it

Cells of the adaptive defense system Lymphocytes

Originate from hemocytoblasts in the red bone marrow B lymphocytes become immunocompetent in the bone

marrow (remember B for Bone marrow) T lymphocytes become immunocompetent in the thymus

(remember T for Thymus) _____________

Arise from monocytes Become widely distributed in lymphoid organs Secrete cytokines (proteins important in the immune

response)

Bukar AlibeMACROPHAGES

Self-Tolerance B and T cells do not attack normal cells of body As cells develop in bone marrow and thymus, any that have antigen

receptors against normal body cells are destroyed by apoptosis (_____________ cell death)

Autoimmune diseases caused by failure of self-tolerance MHC molecules unique to individual person Major histocompatibility complex=MHC MHC marks body cells as self Responsible for tissue/organ rejection stimulates immune response to foreign tissue

Bukar AlibePROGAMMED

Specific (Adaptive) Immune Responses Third Line of Defense: T Cells & Cellular Immunity

T cells defend against foreign or abnormal matter through direct contact

T cell clones Cytotoxic (_____________) T cells Specialize in killing infected cells Insert a toxic chemicals (perforin/fragmentin)

Helper T cells Recruit other cells to

fight the invaders Interact directly with B cells

Regulatory (Suppressor) T cells Release chemicals to suppress the activity of T cells Stop the immune response to

prevent uncontrolled activity A few members of each clone are

memory cells

Bukar AlibeKILLER

Actions of Activated Cytotoxic T Cell on Virus-infected Cells

Cell secretes _____________ Form pore in membrane of infected cell Leads to lysis of infected cell

Cell secretes fragmentins Enter infected cell through perforin-induced pores Trigger apoptosis

Bukar AlibePERFORINS

Role of B Lymphocytes Third Line of Defense: B Cells & Humoral

Immunity B lymphocyte exposure to antigen triggers clonal selection:

memory B cells + plasma cells Memory B cells: _____________ Plasma cells:

Life span = 4-7 days (may be longer for some) Secretes 2000 antibodies specific for antigen per second Antibodies circulate several weeks binding/marking antigen

for destruction May cause phagocytosis or complement-mediated lysis

Bukar AlibeYEARS

Specific (Adaptive) Immune Responses Third Line of Defense: B Cells & Humoral Immunity Secondary humoral responses

Memory cells are long-lived A second exposure causes a

_____________ response The secondary response is

stronger and longer lasting

Primary Response (initial encounter with antigen)

Antigen Antigen binding to a receptor on a specific B cell (lymphocyte) (B cells with non-complementary receptors remain inactive)

Proliferation to form a clone B cells

Plasma cells

Secreted antibody molecules

Clone of cells identical to ancestral cells

Subsequent challenge by same antigen

Memory B cell

Memory B cells

Plasma cells

Secreted antibody molecules

Secondary Response (can be years later)

Bukar AlibeRAPID

Antibodies Antibody Functions:

Binds to specific antigen Aids in inactivation or destruction

of antigen Antibody structure

Four amino acid chains linked by disulfide bonds

Two identical amino acid chains are linked to form a heavy chain

The other two identical chains are light chains

2 specific antigen-binding sites are present

Constant region same within a class of antibodies

_____________ region gives specificity to antigen-binding site

Bukar AlibeVARIABLE

Antibodies Five major immunoglobulin classes (MADGE) All classes: neutralization and agglutination

IgM can activate _____________ IgA found mainly in mucus IgD important in activation of B cell IgG can cross the placental barrier, activate complement and

NK cells, opsonization IgE involved in allergies, histamine release from mast cells and basophils

Bukar AlibeCOMPLEMENT

Immunoglobin Classes

Antibodies: Neutralization

Binding of antibody to antigen blocks activity of _____________

Bukar Alibeantigen

Antibodies: Agglutination

Many antibodies binding to pathogen cause clumping for easy _____________ and identification

Bukar AlibeLOCALIZATION

Antibodies: Opsonization

Variable region of antibody binds to antigen

Constant region of antibody binds to phagocytic cells

Enhances _____________

Binding of antibodies enhances phagocytosis

Bukar AlibePHAGOCYTOSIS

Antibodies: Complement Activation MAC (membrane attack complex)

Antibodies: Enhanced Natural Killer Cell Activity

NK cells have receptors for antibody tail Antibodies mark cells for

destruction NK cells produce pore in

membrane of cells causing _____________

Bukar AlibeLYSIS

Antibody Function

Opsonization

Primary and Secondary Immune Responses 1st exposure to antigen (primary immune response) Takes 10-17 days to occur after first exposure Symptoms of illness occurs during these days Antigen-selected B and T cells proliferate and differentiate

into effector cells _____________ cells Cytotoxic T cells

Secondary immune response Subsequent exposures to antigen Takes 2-7 days to occur Greater magnitude response and more

prolonged Occurs due to presence of

memory cells This is not the same as the 1st, 2nd and 3rd lines of defense!

Bukar AlibePLASMA

Immunity Active Immunity Immune response to vaccine or

pathogen in individual gives immunity Occurs when B cells encounter antigens

and produce antibodies _____________ Immunity

Ready-made antibodies administered No memory cells, so no long-term

immunity

Bukar AlibePASSIVE

Immunization

_____________ = compromised microorganism or its antigens in form not expected to cause disease Induces immune response including production of memory

cells

Bukar AlibeVACCINE

Decline of Measles After Vaccine Introduction

Passive Immunity

Occurs when antibodies are obtained from someone else Conferred naturally from a mother to her fetus (naturally

acquired) Passive immunity from mother to fetus/baby

IgG passes placenta IgA passed in _____________ Conferred artificially from immune serum or gamma

globulin (artificially acquired) Immunological memory does not occur Protection provided by borrowed antibodies

Bukar AlibeBREAST MILK

Functions of Cells and Molecules Involved in Specific Immunity

Suppressor T

Functions of Cells and Molecules Involved in Specific Immunity

Summary of Adaptive (Specific) Immune Response

Organ Transplants and Rejection Major types of grafts

Autografts: tissue from one site to another on the same person Isografts: tissue grafts from an identical person (identical twin) Allografts: tissue taken from another person Xenografts: tissue taken from a different animal species

Autografts and isografts are ideal donors

Xenografts are rarely successful Allografts are more successful with a

closer tissue match Immune system recognizes self from

non-self Need to match donor to recipient

closely Must _____________ immune

system in recipient

Bukar AlibeSUPPRESS

Immune Dysfunctions

Autoimmune Diseases Allergy Immunodeficiency Diseases Stress and the Immune Response

Autoimmune Diseases Inefficient lymphocyte programming Cross-reaction of antibodies produced against foreign antigens with

self-antigens The immune system fails to distinguish between self and nonself The body produces antibodies and sensitized T lymphocytes that

attack its _____________tissues

Bukar AlibeOWN

Disorders of Immunity: Autoimmune Diseases

Immune system treats a part of self like pathogen Immune response induced against that part of the body Examples of autoimmune diseases

Multiple sclerosis: white matter of brain and myelin on nerves are destroyed

Myasthenia gravis: impairs communication between nerves and skeletal muscles

Type I diabetes mellitus: destroys pancreatic beta cells that produce _____________

Systemic lupus erythematosus (SLE): Affects kidney, heart, lung and skin

Rheumatoid arthritis: destroys joints Vitiligo: affects pigmentation of skin

Bukar AlibeINSULIN

Autoimmune Diseases

Multiple sclerosis

Disorders of Immunity: Allergies (Hypersensitivity)

Abnormal, vigorous immune responses Triggered by release of histamine from

IgE binding to mast cells _____________ shockdangerous,

systemic response

Bukar AlibeANAPHYLACTIC

Anaphylactic Shock Severe allergic reactions: massive release of histamine from

mast cells throughout body cause vasodilation decrease blood pressure

Prophylactic = _____________ increases cardiac output and blood pressure increasing blood pressure

Bukar AlibeEPINEPHRINE

Production or function of immune cells or complement is abnormal May be congenital or acquired (_____________) Weak or under-active immune system Problem in any factors of immune response can impair immune

function Examples:

Hodgkins Disease = cancer of lymphatic system AIDS = affects helper T cells

Disorders of Immunity: Immunodeficiency

Bukar AlibeAIDS

Stress and the Immune Response

Stress suppresses immune system Steroid hormones (cortisol)

decrease number of leukocytes Anti-_____________ activity

Autonomic neural input to lymphoid tissue

Bukar AlibeINFLAMMATORY