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Lymphatic System.

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Presentation on theme: "Lymphatic System."— Presentation transcript:

1 Lymphatic System

2 Functions Put excess fluid in tissue spaces back into the blood stream

3 Flow of Lymph Lymphatic capillaries → Lymphatic vessels → Lymphatic Trunks → Collecting Ducts → Veins The lymph will also pass through lymph nodes found along these vessels

4 Lymphatic Capillaries
Closed-ended tubes Form network with blood capillaries Thin-walled Fluid inside is called lymph

5 Lymphatic Vessels and Trunks
Structure is very similar to veins Lymphatic Trunks Larger vessels than lymphatic vessels; drain into collecting ducts

6 Collecting Ducts Two Main Ducts
Thoracic Duct- collects lymph drained from the lower limbs, the abdomen, the left upper limb, and the left side of the thorax, head, and neck Right Lymphatic Duct- collects lymph drained from the right upper limb and the right side of the thorax, neck, and head

7 Tissue Fluid Interstitial fluid surrounding capillaries
Constant movement in and out of capillaries Generally same composition as plasma except plasma proteins Some excess fluid stays and is not recollected by capillaries

8 Formation of lymph Volume pressure of interstitial fluid causes some of the fluid to enter lymphatic capillaries Lymph will return to the bloodstream but will be filtered along the way

9 Movement of Lymph Controlled by
Skeletal muscle movement Pressure changes due to breathing Valves keep the movement going in one direction


11 Lymph Nodes (outside) Usually small and bean shaped
Afferent lymphatic vessels carry lymph into lymph node Come in at various points along convex surface Efferent Lymphatic vessels Carry lymph out of lymph node Come out at hilum (area on the concave side) Blood Vessels and nerves enter at hilum

12 Lymph Node (Inside) Connective tissue encloses lymph node and creates sub-compartments inside Compartments are lymph nodules Space inside the nodule is called a lymph sinus Sinuses are filled with lymphocytes and macrophages

13 Lymph Node Function Filter foreign particles from blood before returning the lymph to the blood stream Immune surveillance

14 Thymus Bilobed structure found in the mediastenum
Largest during childhood Creates T-cells Also endocrine gland- releases thymosins to make T-cells mature after leaving the thymus

15 Spleen Largest lymphatic organ
Found in upper left quadrant near stomach Similar structure to lymph nodes except sinuses contain blood instead of lymph White pulp- high in lymphocytes Red pulp- high in red blood cells, lymphocytes, and macrophages Filters Blood

16 Immunity Protection against pathogens Pathogens include Viruses
Bacteria Fungi Protozoans

17 Types of Immunity Innate vs Adaptive Natural vs Artificial
Active vs Passive

18 Innate Defenses Species resistance
First line of defense- skin and mucous layers Second line of defense Chemical barriers Tears, gastric juices, and sweat interferons Fever Inflammation Phagocytosis

19 Adaptive Immunity Third line of defense Lymphocytes are responsible
Responds to specific antigen on the invading pathogen

20 Origin of Lymphocytes Undifferentiated lymphocytes made by fetal bone marrow T cells Lymphocytes travel to thymus and become T cells T cells either circulate in blood or are found in lymph system B cells Made in marrow B cells either circulate in blood or found in the lymph system

21 Differences in response
Cellular Immune response Attack up close Performed by T cells Humoral immune response Attack from afar Performed by B cells

22 Helper T cells Antigen-presenting cells processes and displays antigen of pathogen Displayed antigen must be matched with a circulating helper T cells antibody receptor Helper T cell is activated

23 Cytotoxic T cells Cytotoxic T cells- attack cells infected virus or cancerous cells must be activated by a matching antigen

24 B cells B cell must match with an antigen
Activated Helper T cell secrete cytokines Cytokines make B cell proliferate to form plasma cells and memory cells Plasma cell secrete antibodies

25 Antibodies Globular proteins Five Types
Immunoglobulin G (IgG)- in plasma and tissue fluids; activates complement system IgA- in exocrine gland secretions IgM- in plasma; activates complement system IgD- found on surfaces of B cells; activates B cells IgE- in exocrine gland secretions; associated with allergic reaction

26 Antibody Function Attack Directly
Agglutinate- clump pathogens together Precipitate- make pathogen insoluble Neutralize- cover or destroy toxic part of antigen

27 Antibody Function Activate compliment Compliment Function
Done by shape change of IgG and IgM Starts a series of rxns that activate the compliments circulating in the plasma Compliment Function Opsonization- coating antigen-antibody complex Chemotaxis- bringing macrophages to the area Lysis- rupturing membranes Agglutination Neutralization

28 Memory Cells Memory T and B cells- circulate after primary immune response Body will be able to respond quickly during secondary immune response

29 Allergic Reactions Immune response to everyday, non-harmful antigens (allergens) Delayed-reaction allergy Exposure to allergen on skin Collects T cells and macrophages in the area Causes dermatitis

30 Allergic Reactions Immediate-reaction allergy Occurs within minutes
First exposure- B cells become sensitized; IgE is attached to basophils and mast cells Subsequent exposures- mast cells and basophils secrete several substances including histamine These substances produce the reactions seen in allergy reactions


32 Transplantation Transplant tissue or organ
Antigen is recognized as foreign and starts immune response Tissue matching helps minimize reaction Immunosuppressive drugs- suppress immune reaction

33 Autoimmunity Cytotoxic T cells cannot correctly identify self cells and attacks self cells Why? “catalogue” is incomplete Pathogen borrows self antigens during attack Pathogen antigen is very similar to a self antigen

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