University:
Texas A&M University
Course:
BIOL 319 | Integrated Human Anatomy and Physiology I
Academic year:

2023
Views:

144

Pages:

45
Author:

Caroline Mcfarland

Lymphoid System EXAMPLES OF IMMUNE RESPONSE • REACTION AGAINST MICROORGANISMS: BACTERIA, VIRUSES, PARASITES • REACTION AGAINST TUMOR CELLS • ALLERGIC REACTIONS: HAY FEVER, POISON IVY • AUTOIMMUNE REACTION: ARTHRITIS, TYPE I DIABETES • GRAFT REJECTION OBJECTIVES PURPOSE OF THE IMMUNE SYSTEM CELLULAR BASIS OF IMMUNITY EFFECTORS OF RESPONSE INDUCTION OF THE RESPONSE ONTOGENY FUNCTIONS OF THE IMMUNE SYSTEM • PROTECTION AGAINST FOREIGN INVADERS INTO BODY • PRODUCE / PROTECT GERM FREE ENVIRONMENT OF THE BODY Three Key Steps of Combating Infections reak the cycle of transmission ill the infectious agent ncrease host resistance e.g., increase immunity of host Lines of Defense First Line: Physical Barrier – Skin: Stratum Cornium – HCl In Stomach – Mucus In Intestines reak the cycle of transmission Lines of Defense •Second line: Phagocytes at work • Neutrophils to ill the infectious agent Monocytes - macrophage ncrease host resistance through Immunity Characteristics of Immunity Acquired - requires exposure to antigens Specificity - response is unique to exposure Memory - remembers previous exposure Characteristics of Immunity Acquired Must be developed Specificity Antibodies made are specific to specific molecules on the antigen of exposure Characteristics of Immunity Memory: quick second response – Long lived cells Memory of lymphocytes is the basis of immunization by vaccination. Your lymphocytes remember the antigen used in your vaccination and mounts a quick and enhanced response when the same antigen is presented again. Types of Immune Response •Antibody: mediated – Glycoproteins recognize and bind to antigens •Cell: mediated – Specifically active cells recognize cell - bind antigens Slide 32583, see colonies of developing cells and for blood vessels in the bone marrow 112 Smear of bone marrow cells Ref code #5 thymus Bone marrow Thymus Thymus, newborn Outer darkly staining areas (cortex) and lighter central areas (medulla). Medulla Thymocytes Cortex Medulla Continuous capillaries, sheathed by epithelial reticular cells around each, characterizes blood vessels in the thymus cortex and is responsible for the blood thymus barrier. Also there are no afferent lymphatics in the thymus. Thymus, newborn Epithelial reticulum cells Cortex Mitotic figures frequently, which reflect the high proliferative rate of these cells. THYMUS Blood-thymus barrier in cortex RETICULUM FRAMEWORK - EPITHELIUM Epithelial reticulum cells Hassall's corpuscles #5 Lymph node Large round structures (follicles), Cortex Medulla Germinal center, Subcapsulary sinus Afferent lymphatic duct Lymph node Capsule Afferent lymphatic duct 116 Subscapular space Predominantly T lymphocytes Perifollicular area Predominantly B lymphocytes, around germinal center Germinal center High endothelial venules = sites where blood-borne lymphocytes enter the node. Parafollicular region Parafollicular region 116 Follicle High endothelial venule Part of follicle = Site of lymphocyte entry into the lymph node (one way street) Typical flat endothelium INDUCTION OF RESPONSE •PERIPHERAL ORGAN NEEDED TO GET ANTIGEN AND RESPONSIVE CELL TO INTERACT – LYMPHOCYTE RECIRCULATING – APPROPRIATE CONTEXT Lymph sinus in lymph node Lymph sinus Medullary cords Ref code # 5, 6 Parafollicular region Efferent lymphatic duct? Esophagus and trachea, monkey Tonsil Ref code #5 Tonsil Tonsil Fundic stomach Plasma cells large intestine in Colon, monkey • Appendix (Slide 32412). Lymphoid tissues Lymphoid tissues are important in the defense against ingested micro-organisms Spleen Spleen (reticulum stain)capsule and reticulum fibers Spleen Venous sinuses, and Billroth's strands Capsule the red pulp. white pulp Primary function Of the spleen is filtration of blood. Spleen has no afferent lymphatics Central artery Spleen Marginal zone Billroth's (splenic) strands Penicillar arteries in marginal zone Follicles White pulp Central artery Red pulp Venous sinuses Billroth's (splenic) strands Spleen central artery PENICILLARY ARTERIES Marginal zone Spleen (reticulum stain)- reticulum fibers in strands between venous (blood) sinus Litteral cells of spleenic venule Spleen Penicillar arteries Billroth’s strand or spleenic strand Littoral cells: picketfence type endothelial cells of vascular sinus Bone marrow Lymphocyte is a main player of immune response Blood in vessel Life Cycle of Lymphocytes Fetal organs Bone marrow Primary lymphoid organs (Antigen independent development) - Thymus – T lymphocytes - Bone marrow - B lymphocytes Secondary lymphoid organs (Antigen dependent development) – Lymph nodes – Lymphoid nodules – Spleen In summary Questions on the lymphoid system 1. The main purpose(s) of lymphocyte traffic, the circulation of lymphocytes throughout the body, is: a. to place the responsible lymphocytes in the region of specific antigens b. to stimulate lymphocyte growth through meiosis c. to clean out the lymphatics ducts d. a and b e. a, b, and c 2. The function(s) of the spleen include: a. clean the blood of particulate matter b. to remove worn red blood cells c. to remove ribosomes from reticulocytes d. a and b e. a, b, and c 3. Which lymphatic organ(s) contain(s) penicilliary arteries or both afferent and efferent lymphatic vessels? a. lymph node b. spleen c. thymus d. a and b e. a, b, and c

The Lymphoid System

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