Venous Arterial system system Heart
Lymph duct Lymph trunk
Lymph node
Lymphatic system
Lymphatic collecting vessels, with valves
Lymph capillary Tissue fluid (becomes lymph)
Blood Loose connective capillaries tissue around capillaries © 2018 Pearson Education, Inc. 1 Tissue fluid Tissue cell Lymphatic capillary
Blood capillaries
(a) Arteriole Venule
© 2018 Pearson Education, Inc. 2 Fibroblast in loose connective tissue
Flaplike minivalve
Filaments anchored to Endothelial connective cell tissue (b)
© 2018 Pearson Education, Inc. 3 Entrance of right Regional lymphatic duct into right lymph nodes: subclavian vein
Cervical Internal jugular vein nodes Thoracic duct entry into left subclavian vein Axillary nodes Thoracic duct Aorta Spleen Cisterna chyli (receives lymph drainage from Inguinal digestive organs) nodes
Lymphatics
KEY: Drained by the right lymphatic duct Drained by the thoracic duct © 2018 Pearson Education, Inc. 4 Germinal center in Afferent follicle Capsule lymphatic vessels Subcapsular sinus
Trabecula
Afferent Efferent lymphatic lymphatic vessels vessels Hilum Cortex Medullary sinus Follicle Medullary cord
© 2018 Pearson Education, Inc. 5 Tonsils (in pharyngeal region)
Thymus (in thorax; most active during youth)
Spleen (curves around left side of stomach)
Peyer’s patches (in intestine)
Appendix
© 2018 Pearson Education, Inc. 6 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
© 2018 Pearson Education, Inc. 7 © 2018 Pearson Education, Inc. 8 © 2018 Pearson Education, Inc. 9 © 2018 Pearson Education, Inc. 10 Injurious agents
Cells damaged
Release kinins, histamine, and other chemicals
Blood vessels Capillaries Neutrophils and then dilate become “leaky” monocytes (and other WBCs) enter area
Increased blood Edema (fluid in Clotting Removal of flow into area tissue spaces) proteins damaged/dead enter area tissue cells and pathogens from area Redness Heat Pain Swelling
Brings more nutrients and Fibrin oxygen to area barrier
Increases Possible metabolic temporary rate of limitation of tissue cells joint movement
Healing
© 2018 Pearson Education, Inc. 11 Positive 3 chemotaxis Inflammatory chemicals diffusing from the inflamed site act as chemotactic agents
Neutrophils 1 Enter blood from bone marrow 2 Diapedesis and roll along the vessel wall
Capillary wall Endothelium Basement membrane © 2018 Pearson Education, Inc. 12 (a) A macrophage (purple) uses its cytoplasmic extensions to ingest bacillus-shaped bacteria (pink) by phagocytosis. Scanning electron micrograph.
© 2018 Pearson Education, Inc. 13 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.
5 Exocytosis of the vesicle removes indigestible and (b) Events of phagocytosis residual material. © 2018 Pearson Education, Inc. 14 Membrane attack complex forming
Antibodies attached to Pore pathogen’s membrane
Cytoplasm H2O H2O
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. forming a membrane attack complex (a MAC attack). to rush into the cell.
© 2018 Pearson Education, Inc. 15 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 antigen encounter, and activation to 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 immunocompetence there. B cells develop immunocompetence in red bone marrow. Thymus Bone marrow
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 activated.
3 Antigen-activated (mature) immunocompetent lymphocytes (effector 3 cells and memory cells) circulate continuously in the bloodstream and lymph and throughout the lymphoid organs of the body.
© 2018 Pearson Education, Inc. 16 Primary response Free antigen (initial encounter Antigen binding with antigen) to a receptor on a specific B cell (B cells with Proliferation to non-complementary form a clone receptors remain Activated B inactive) cells
Plasma Memory cells B cell Secreted antibody molecules Subsequent Secondary response challenge (can be years later) by same Clone of cells antigen results identical to in more rapid ancestral cells response
Plasma cells Secreted Memory antibody B cells molecules © 2018 Pearson Education, Inc. 17 Humoral immunity
Active Passive
Naturally Artificially Naturally Artificially acquired acquired acquired acquired Infection; Vaccine; Antibodies Injection of contact with dead or passed from donated pathogen attenuated mother to antibodies pathogens fetus via (gamma placenta; or globulin) to infant in her milk
© 2018 Pearson Education, Inc. 18 (a)
© 2018 Pearson Education, Inc. 19 Antigen-binding sites
V V V V
C C Light chain
Disulfide Heavy bonds C C chain
(b) © 2018 Pearson Education, Inc. 20 Antigen Antigen-antibody Antibody complex
Inactivates by Fixes and activates
Neutralization Precipitation (masks dangerous Agglutination (soluble Complement parts of bacterial (cell-bound antigens) exotoxins; viruses) antigens)
Enhances Enhances Leads to
Phagocytosis Inflammation Cell lysis
Chemo- taxis
Histamine release © 2018 Pearson Education, Inc. 21