Lymphatic system Lymphatic system

And immunityAnd immunity

Lymphatic pathways Lymphatic pathways

Collecting ductsCollecting ducts Thoracic ductThoracic duct

Larger and longer collecting ductLarger and longer collecting duct Lower limbs, abdominal regions, left upper limb, and left Lower limbs, abdominal regions, left upper limb, and left

side of the thorax, head, and neck and empties into the left side of the thorax, head, and neck and empties into the left subclavian vein subclavian vein

Right lymphatic ductRight lymphatic duct Right side of the head and neck, right upper limb, and right Right side of the head and neck, right upper limb, and right

thorax and empties into the right subclavian veinthorax and empties into the right subclavian vein Enters the venous system and becomes part of the Enters the venous system and becomes part of the

plasma just before blood returns to right atriumplasma just before blood returns to right atrium

Tissue fluid and lymphTissue fluid and lymph

Tissue fluid formationTissue fluid formation Originates from blood plasma and is composed of Originates from blood plasma and is composed of

water and dissolved substances that leave blood water and dissolved substances that leave blood capillaries by diffusion and filtrationcapillaries by diffusion and filtration

Lymph formation and functionLymph formation and function increased pressure forces tissue fluid into lymphatic increased pressure forces tissue fluid into lymphatic

capillaries where it becomes lymphcapillaries where it becomes lymph Lymph returns small proteins back to bloodstream Lymph returns small proteins back to bloodstream Transports foreign particles to lymph nodesTransports foreign particles to lymph nodes

Lymph movement is influenced by muscle Lymph movement is influenced by muscle movement and breathing movementsmovement and breathing movements

Lymph nodesLymph nodes

Located along the lymph pathwaysLocated along the lymph pathways Contain large numbers of lymphocytes and Contain large numbers of lymphocytes and

macrophages that fight invading microorganismsmacrophages that fight invading microorganisms Hilum- indented region where blood vessels and Hilum- indented region where blood vessels and

nerves join the node and efferent lymphatic vessels nerves join the node and efferent lymphatic vessels exitexit

Lymph nodules- masses of lymphoctes and Lymph nodules- masses of lymphoctes and macrophages that are the structural unitmacrophages that are the structural unit

Lymphatic sinuses- complex network of chambers and Lymphatic sinuses- complex network of chambers and tunnels through which lymph circulates tunnels through which lymph circulates Area where macrophages are highly concentrated Area where macrophages are highly concentrated

Lymph node functionsLymph node functions

Two primary functionsTwo primary functions Filtering potentially harmful particles from Filtering potentially harmful particles from

lymph before returning it to the bloodstream lymph before returning it to the bloodstream Immune surveillance provided by Immune surveillance provided by

lymphocytes and macrophages lymphocytes and macrophages Centers for lymphocyte productionCenters for lymphocyte production

Attack infecting viruses, bacteria and other Attack infecting viruses, bacteria and other microorgansimsmicroorgansims

Macrophages engulf and destroy foreign substances, Macrophages engulf and destroy foreign substances, damaged cells, and cellular debrisdamaged cells, and cellular debris

ThymusThymus Contain abundant lymphocytesContain abundant lymphocytes

Some mature into T cellsSome mature into T cells Leave the thymus and provide immunityLeave the thymus and provide immunity

Epithelial cells secrete thymosin Epithelial cells secrete thymosin Stimulates maturation of T cells after they leave Stimulates maturation of T cells after they leave

the thymus and migrate to other lymphatic the thymus and migrate to other lymphatic tissuestissues

Spleen Spleen

Largest lymphatic organLargest lymphatic organ Contain two types of tissueContain two types of tissue

White pulpWhite pulp Distributed throughout the spleen in tiny islandsDistributed throughout the spleen in tiny islands Composed of splenic nodules and contain many Composed of splenic nodules and contain many

lymphoctyeslymphoctyes

Red pulp Red pulp Fills remaining sinuses and surround venous sinusesFills remaining sinuses and surround venous sinuses Contains numerous red blood cells, lymphocytes, and Contains numerous red blood cells, lymphocytes, and

macrophagesmacrophages

Spleen cont.Spleen cont. Phagocytic macrophages remove old, Phagocytic macrophages remove old,

fragile blood cells and cellular debrisfragile blood cells and cellular debris Also engulf and destroy foreign particles Also engulf and destroy foreign particles Filters blood Filters blood

Body defensesBody defenses

Two main typesTwo main types Nonspecific defensesNonspecific defenses

Respond rapidly Respond rapidly

Specific defensesSpecific defenses Slower to respondSlower to respond

Work together to protect the body against Work together to protect the body against infection infection

Nonspecific defenses Nonspecific defenses

Species resistanceSpecies resistance The fact that a given kind of species The fact that a given kind of species

develops diseases that are unique to itdevelops diseases that are unique to it

Mechanical barriersMechanical barriers Skin and mucous membranesSkin and mucous membranes Provide a first line of defenseProvide a first line of defense

Nonspecific defense cont.Nonspecific defense cont.Second line defenseSecond line defense

Chemical barriersChemical barriers Certain cells produce interferonsCertain cells produce interferons

FeverFever Elevated body temperatureElevated body temperature

Causes liver and spleen to hide ironCauses liver and spleen to hide iron Phagocytic cells attack more vigorously Phagocytic cells attack more vigorously

Nonspecific defensesNonspecific defenses InflammationInflammation

Body’s response to injury or infectionBody’s response to injury or infection Produces localized redness, swelling, heat, and painProduces localized redness, swelling, heat, and pain

Infected cells produce chemicals attracting white Infected cells produce chemicals attracting white blood cells blood cells mass of white blood cells may form a thick fluid called pusmass of white blood cells may form a thick fluid called pus

fibrinogen and other clotting factors enclosing the fibrinogen and other clotting factors enclosing the area to prevent spread of pathogensarea to prevent spread of pathogens

PhagocytosisPhagocytosis Remove foreign particles from lymph as it moves Remove foreign particles from lymph as it moves

through the lymphatic systemthrough the lymphatic system

Specific defenses-Specific defenses-immunityimmunity

third line defensethird line defense AntigensAntigens

Any substance that is capable of exciting our Any substance that is capable of exciting our immune system and provoking an immune immune system and provoking an immune responseresponse

Lymphocyte functionsLymphocyte functions T cells and B cells respond to antigensT cells and B cells respond to antigens

Specific defenseSpecific defense AntibodiesAntibodies Immunoglobulin GImmunoglobulin G

In plasma and tissue fluidIn plasma and tissue fluid Effective against toxins, bacteria and virusesEffective against toxins, bacteria and viruses Activates immune system enzymes--complementActivates immune system enzymes--complement

Immunoglobulin AImmunoglobulin A In exocrine gland secretionsIn exocrine gland secretions

Immunoglobulin MImmunoglobulin M Develops in plasma in response to antigensDevelops in plasma in response to antigens

Immunoglobulin DImmunoglobulin D Surface of most B cells and activates B cellsSurface of most B cells and activates B cells

Immunoglobulin EImmunoglobulin E Appears in exocrine secretionsAppears in exocrine secretions Associated with allergic reactionsAssociated with allergic reactions

Specific defensesSpecific defenses

Immune responseImmune response Primary immune response- antibodies are released Primary immune response- antibodies are released

and transported throughout the body destroying and transported throughout the body destroying antigen bearing agentsantigen bearing agents

Some B cell become dormant memory cells Some B cell become dormant memory cells producing a secondary immune responseproducing a secondary immune response

Allergic reactionsAllergic reactions An immune attack against a nonharmful substanceAn immune attack against a nonharmful substance Can damage tissueCan damage tissue

Transplant and tissue Transplant and tissue rejectionrejection

The danger the immune system poses to The danger the immune system poses to transplanted tissue is that the recipient’s cells transplanted tissue is that the recipient’s cells may recognize the donor’s tissue a foreign may recognize the donor’s tissue a foreign and attempt to destroy transplanted tissueand attempt to destroy transplanted tissue

Immunosuppresive drugs are used to reduce Immunosuppresive drugs are used to reduce rejection of transplanted tissuerejection of transplanted tissue Interfere with recipient’s immune response by Interfere with recipient’s immune response by

suppressing formation of antibodies or production suppressing formation of antibodies or production of T cellsof T cells Leaves unprotected against infectionsLeaves unprotected against infections

autoimmunityautoimmunity

Does not distinguish self from non-self producing Does not distinguish self from non-self producing autoantibodiesautoantibodies Attack and damage tissues and organsAttack and damage tissues and organs

Specific nature of autoimmune disorder depends Specific nature of autoimmune disorder depends on the cell type that are the target of the immune on the cell type that are the target of the immune attackattack Virus may borrow proteins from host cell’s surface and Virus may borrow proteins from host cell’s surface and

incorporate them on its surfaceincorporate them on its surface T cell escape education of self in thymusT cell escape education of self in thymus Nonself antigen resembles a self antigenNonself antigen resembles a self antigen