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Lecture 22

ANAT 103 Lecture 22: Ch22 ANAT 103

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Drexel University
ANAT 103
Mary Flynn

Ch 22 Lymphatic System Lymphatic System - Consists of lymph fluid, lymphatic vessels, lymphatic tissue and bone marrow Lymphatic Functions 1) Drain excess interstitial fluid (want to return fluid back to the blood) a) Left drains up into the left thoracic duct that feeds into left subclavian vein where it returns the intersitial fluid 2) Transport dietary fats a) Large lipids need to be carried by lacteles (of small intestine) so they dont clog arteries 3) Carry out immune response Lymphatic Vessels - Begin as lymphatic capillaries located between cells - The capillaries merge and form the vessels w/ thin walls and numerous valves - Lymph flows through the lymph nodes (bean shape organs w/ B and T cells) along the vessels and into lymph trunks (lumbar, intestinal, bronchomediastinal, subclavian adn jugular) - Travels from the lymph trunks to either the thoracic duct or the right lymphatic duct and then into venous blood Left Side: 1) Thoracic Duct begins at the cisterna chyli a) Cistera gets lymph from the left upper body and entire body after the ribs b) Drains lymph into the left internal jugular and left subclavian veins Right Side 1) Right lymphatic duct receives lymph from upper right side of body a) Drains into the right internal jugular and right subclavian veins Formation and Flow of Lymph - Excess fluid drains into the lymph vessels to become lymph - Intersitial fluid → lymph capillaries → lymph vessels → lymph trunks → lymph ducts → internal jugular or subclavian veins Lymphatic Organs and Tissues 1) Primary Lymphatic Organs a) Sites where stem cells become immunocompetent (able to make an immune response) b) Red bone Marrow i) makes immunocompetent B cell and pre-T cells c) Thymus i) changes pre-T cells to immunocompetent T cells 2) Secondary Lymphatic Organs and Tissues a) Sites where immune responses occur b) Lymph node i) Trabeculae: (1) Extensions from capsule that divide the node into compartments, provide support and provide a route for blood vessels into the node ii) Flow of Lymph: (1) Afferent lymphatic vessel (toward) (a) Has valves that open inward towards the node (2) Subcapsular Sinus (a) Irregular channel immediately beneath the capsule (3) Trabecular Sinus (4) Medullary Sinus (5) Efferent Lymphatic Vessels (away) (a) Emerge from the hilum (blood vessels enter and leave here too) (b) Valves open away from the center of the node iii) Functions as a filter (1) Lymph enters the node (2) Foreign stuff is trapped by the sinus (3) Macrophages eat the substances (4) Filtered lymph leaves at other end iv) B and T Cells: (1) pathogen safeguards v) Dendritic Cells: (1) Helps to alert the system of the presence of pathogens c) Spleen i) Receive blood and allows it to be exposed to B+T cells ii) White and Red pulp (1) White pulp: (a) Has B,T lymphocytes and macrophage cells (i) WBC act on blood coming in (b) Surrounds the central arteries (i) Where blood flows into the spleen (2) Red Pulp: (a) Functions: (i) place where defective and worm out RBC cells go and get pulled apart (ii) Has platelets storage (iii) Makes stem cells/ RBCs (Hemopoiesis) during fetal life (b) Consist of blood filled venous sinuses and splenic cords iii) Will rupture when traumatized and must be taken out (1) Increased risk of infection w/o spleen d) lymphatic nodules aggregates i) Masses of lymphatic tissue not surrounded by a capsule ii) MALT (Mucosa associated lymphatic tissue): nodules lining the GI, urinary, reproductive and respiratory tract iii) GALT (gut associated) Innate immunity - Responses present at birth that protect against general invasion of pathogens and toxins - Non-specific barriers - 2 Lines of defense: - Skin and mucous - Intact Epidermis of skin → physical barrier - Mucous Membranes → inhibit microbes - Mucus → trap microbes in respiratory and GI tract - Lacrimal Apparatus → wash away pathogens via tears - Lysozyme in tears → cause pathogens to lyse (break open and die) - Saliva → wash away microbes on teeth - Urine → washes microbes from urethra and retards colonization - Sebum → oil w/ protective acidic film - Internal defenses - Antimicrobial Proteins: - Interferons → interfere w/ viral spread; alerts surrounding cells of nearby infection to induce antiviral protein synthesis - Proteins of the complement system enhance immune defenses - Cytolysis (break open), phagocytosis (attract phagocytes to area of where to eat), inflammation (intensify) - Natural killer cells → part of WBC family - Kill any abnormal infected cells to prevent spread - Binds to target cell, releases granules with perforin that inserts into the plasma membrane and creates holes which allows ECF to get inside and make it burst (cytolysis) - Can release granzymes which induce the cell to undergo apotosis and self-destruct. Released microbes would be eaten by phagocytes - Phagocytes → eating cells - Neutrophils and macrophages - Inflammation → swelling, redness, heat, pain - Non-specific defence with three stages: - Vasodilation and Increased Blood Vessel Permeability - Vasodilation increases diameter and allows more blood to flow to damaged area, remove toxins and dead cells - Increased permeability allows defense proteins to enter the injured area from the blood - MAST cells release histamine which cause vasodilation - Heat and redness occur from blood accumulating in damaged area and from rush of cells - Swelling occurs from increased permeability (more fluid goes from plasma to the tissue) - Pain receptors are pressed on by swelling, prostaglandins (stimulate pain generators), Kinis affect nerve endings - Emigration of Phagocytes - Chemotaxis: chemicals released by damaged cells or WBC attract phagocytes to damaged area - Emigration: Neutrophils stick to the blood vessel lining and squeeze through the wall to damages area - Monocytes arrive as neutrophils begin to die off and transform into wandering macrophages large enough to engulf damaged tissue, worn neutrophils and microbes - Tissue repair - Fever → elevated body temp - Intensify internferons ability to comm
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