(A) Arteriole Venule Fibroblast in Loose Connective Tissue Flapli

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Venous Arterial system system Heart

Lymph duct Tissue fluid Lymph trunk Tissue cell Lymphatic Lymph node capillary

Lymphatic system

Lymphatic collecting Blood vessels, with valves capillaries

Lymph capillary Tissue fluid (becomes lymph)

Entrance of right Fibroblast in loose Regional lymphatic duct into right lymph nodes: connective tissue subclavian vein

Flaplike Cervical Internal jugular vein minivalve nodes Thoracic duct entry into left subclavian vein Axillary nodes Thoracic duct Aorta Spleen Cisterna chyli (receives lymph drainage from Inguinal digestive organs) nodes

Filaments anchored to Lymphatics Endothelial connective cell tissue KEY: (b) Drained by the right lymphatic duct Drained by the thoracic duct © 2018 Pearson Education, Inc. 3 © 2018 Pearson Education, Inc. 4

Tonsils (in pharyngeal region) Germinal center in Afferent follicle Capsule Thymus (in thorax; lymphatic most active during vessels Subcapsular youth) sinus

Trabecula

Afferent Spleen (curves lymphatic Efferent lymphatic around left side of vessels vessels stomach)

Hilum Cortex Peyer’s patches Medullary sinus (in intestine) Follicle Medullary cord Appendix

The Immune System

Adaptive (specific) defense Innate (nonspecific) defense mechanisms mechanisms

First line of defense Second line of defense Third line of defense

• Skin • Phagocytic cells • Lymphocytes • Mucous membranes • Natural killer cells • Antibodies • Secretions of skin • Antimicrobial proteins • Macrophages and other and mucous • The inflammatory antigen-presenting cells membranes response • Fever

Injurious agents

Cells damaged

Release kinins, histamine, and other chemicals

Blood vessels Capillaries Neutrophils and then dilate become “leaky” monocytes Positive (and other WBCs) 3 enter area chemotaxis Inflammatory Increased blood Edema (fluid in Clotting Removal of chemicals diffusing flow into area tissue spaces) proteins damaged/dead from the inflamed enter area tissue cells and pathogens site act as chemotactic from area agents Redness Heat Pain Swelling Neutrophils Brings more nutrients and Fibrin 1 Enter blood from bone marrow 2 Diapedesis oxygen to area barrier and roll along the vessel wall

Increases Possible metabolic temporary rate of limitation of tissue cells joint movement

Slide 1 1 Phagocyte adheres to pathogens.

2 Phagocyte Phagosome engulfs the (phagocytic particles, forming vesicle) a phagosome.

Lysosome 3 Lysosome fuses with the phagocytic vesicle, forming a phagolysosome. Acid hydrolase 4 Lysosomal enzymes enzymes digest the pathogens or debris, leaving a residual body. (a) A macrophage (purple) uses its cytoplasmic extensions to ingest bacillus-shaped 5 Exocytosis of bacteria (pink) by phagocytosis. Scanning the vesicle electron micrograph. removes indigestible and (b) Events of phagocytosis residual material. © 2018 Pearson Education, Inc. 13 © 2018 Pearson Education, Inc. 14

Slide 1

KEY: Red bone marrow: site of lymphocyte origin

Primary lymphoid organs: sites of Red development of immunocompetence as bone marrow B or T cells Secondary lymphoid organs: sites of Membrane attack antigen encounter, and activation to complex forming become effector and memory B or T cells

Immature (naive) lymphocytes 1 Lymphocytes destined to become T cells migrate (in blood) to the thymus and develop 1 Antibodies immunocompetence there. B cells develop immunocompetence in red bone marrow. attached to Pore Thymus pathogen’s Bone marrow membrane

2 2 Immunocompetent but still naive lymphocytes leave the thymus and bone Lymph nodes, marrow. They “seed” the lymph nodes, spleen, and other spleen, and other lymphoid tissues, where lymphoid tissues they encounter their antigens and become Cytoplasm H2O H2O activated.

1 Activated complement proteins attach to 2 MAC pores in the 3 This influx of water pathogen’s membrane in step-by-step sequence, membrane allow water causes cell lysis. 3 Antigen-activated (mature) forming a membrane attack complex (a MAC attack). to rush into the cell. immunocompetent lymphocytes (effector 3 cells and memory cells) circulate continuously in the bloodstream and lymph and throughout the lymphoid organs of the body.

Free antigen Primary response (initial encounter Antigen binding Humoral with antigen) to a receptor on a immunity specific B cell (B cells with Proliferation to non-complementary receptors remain Activated B form a clone inactive) cells

Active Passive

Plasma Memory cells B cell Secreted antibody molecules Naturally Artificially Naturally Artificially Subsequent Secondary response challenge acquired acquired (can be years later) acquired acquired by same Clone of cells Infection; Antibodies antigen results Vaccine; Injection of identical to in more rapid contact with dead or passed from donated ancestral cells response pathogen attenuated mother to antibodies pathogens fetus via (gamma Plasma placenta; or cells globulin) to infant in Secreted Memory antibody her milk B cells molecules © 2018 Pearson Education, Inc. 17 © 2018 Pearson Education, Inc. 18 3/6/20

Antigen-binding sites

V V V V

C C Light chain

Disulfide Heavy bonds C C chain

Antigen Antigen-antibody Antibody complex

Inactivates by Fixes and activates

Neutralization Agglutination Precipitation (masks dangerous (cell-bound (soluble Complement parts of bacterial exotoxins; viruses) antigens) antigens)

Enhances Enhances Leads to

Phagocytosis Inflammation Cell lysis

Chemo- taxis