The Lymphatic and Immune Systems. Main structures of the lymphatic system –Lymphatic vessels Main components of the immune system –Lymphocytes –Lymphoid

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  • The Lymphatic and Immune Systems

  • The Lymphatic and Immune SystemsMain structures of the lymphatic systemLymphatic vessels

    Main components of the immune systemLymphocytesLymphoid tissueLymphoid organs

  • The Lymphatic SystemLymphatic vessels collect tissue fluid from loose connective tissue Carry fluid to great veins in the neckFluid flows only toward the heartFigure 20.1

  • Functions of Lymphatic VesselsCollect excess tissue fluid and blood proteins

    Return tissue fluid and blood proteins to bloodstream

  • Orders of Lymphatic VesselsLymph capillaries - smallest lymph vessels first to receive lymph

    Lymphatic collecting vesselscollect from lymph capillaries

  • Orders of Lymphatic VesselsLymph nodesscattered along collecting vessels

    Lymph trunkscollect lymph from collecting vessels

    Lymph ductsempty into veins of the neck

  • Lymphatic CapillariesLocated near blood capillaries

    Receive tissue fluid from Connective Tissue- increased volume of tissue fluid - minivalve flaps open and allow fluid to enter

    Highly permeability allows entrance oftissue fluidbacteria, viruses, and cancer cells

  • Lymphatic CapillariesLacteals specialized lymphatic capillaries- located in the villi of the small intestines- receive digested fats- fatty lymph chyle

  • Lymphatic CapillariesFigure 20.2a, b

  • Lymphatic Collecting VesselsAccompany blood vessels

    Composed of the same three tunics as BVs

    Contain more valves than veins do helps direct the flow of blood

    Lymph propelled bybulging of skeletal musclespulsing of nearby arteriestunica media of the lymph vessels

  • Lymph NodesCleanse the lymph of pathogens

    Human body contains around 500

    Lymph nodes are organized in clusters

  • Lymph NodesFigure 20.3

  • Microscopic Anatomy of a Lymph NodeFibrous capsule surrounds lymph nodes

    Trabeculae connective tissue strands

    Lymph vesselsAfferent lymphatic vesselsEfferent lymphatic vessels

  • Figure 20.4aLymph Node Microscopic Anatomy

  • Lymph TrunksLymphatic collecting vessels converge

    Five major lymph trunks:

    Lumbar trunks - receives lymph from lower limbs

    Intestinal trunk - receives chyle, digestive organs

    Bronchomediastinal trunks - collects lymph from thoracic viscera

    Subclavian trunks - receive lymph from upper limbs and thoracic wall

    Jugular trunks - drain lymph from head & neck

  • Lymph Nodes, Trunks, and DuctsFigure 20.3

  • The Lymphatic TrunksFigure 20.6a

  • Lymph DuctsCisterna chylilocated at the union of lumbar and intestinal trunks

    Thoracic ductAscends along vertebral bodiesEmpties into venous circulation Junction of left internal jugular and left subclavian veinsDrains three quarters of the body

    Right lymphatic duct empties into right internal jugular and subclavian veins

  • Palpation

  • Mononucleosis (aka Mono or the kissing disease)What is it? Mononucleosis is a viral infection causing fever, sore throat, and swollen lymph glands, especially in the neck.

  • MonoMononucleosis, or mono, is often spread by saliva and close contact. It is known as "the kissing disease," and occurs most often in those age 15 to 17. However, the infection may develop at any age.

  • MonoMono is usually linked to the Epstein-Barr virus (EBV), but can also be caused by other organisms such as cytomegalovirus (CMV).

  • MonoBlood work often reveals a higher-than-normal white blood cell (WBC) count and unusual-looking white blood cells called atypical lymphocytes, which are seen when blood is examined under a microscope. Atypical lymphocytes and abnormal liver function tests are a hallmark sign of the disease.Amonospot testwill be positive for infectious mononucleosis.

  • To relieve typical symptoms:Drink plenty of fluids.Gargle with warm salt water to ease a sore throat.Get plenty of rest.Takeacetaminophenoribuprofenfor pain and fever.You should also avoid contact sports while the spleen is swollen (to prevent it from rupturing).

  • The Immune SystemRecognizes specific foreign molecules

    Destroys pathogens effectively

    Key cells lymphocytes

    Also includes lymphoid tissue and lymphoid organs

  • LymphocytesInfectious organisms attacked by inflammatory responsemacrophages, then lymphocytes

    Cytotoxic T lymphocytes Attack foreign cells directlyBinds to antigen-bearing cellsPerforates cell membraneSignals cell to undergo apoptosis

  • LymphocytesB lymphocytes- become plasma cells- secrete antibodies, mark cells for destruction by macrophages

  • Figure 20.7

  • Lymphocyte ActivationLymphocytes originate in bone marrow

    T lymphocytes travel to the thymus gland

    B lymphocytes stay in bone marrow

    Able to recognize a unique antigen

    Gain immunocompetencetravels through blood streammeets and binds to a specific antigen

  • Lymphocyte ActivationActivating T or B cells produceEffector lymphocytesShort-lived, attack immediatelyMemory lymphocytesWait until body encounters their antigen againBasis of acquired immunityGuard against subsequent infections

  • Figure 20.8

  • Lymphoid TissueMost important tissue of the immune system

    Two general locations: Mucous membranes of digestive, urinary, respiratory, and reproductive tracts- Mucosa-associated lymphoid tissue (MALT)

    Lymphoid organs (except thymus)

  • Lymphoid OrgansPrimary lymphoid organsBone marrowThymus

    Secondary lymphoid organsLymph nodes, spleen, tonsilsAggregated lymphoid nodulesAppendix

  • Figure 20.10Lymphoid OrgansDesigned to gather, destroy infectious microorganisms

  • ThymusImmature lymphocytes develop into T lymphocytes - secretes thymic hormones - most active in childhood

    Functional tissue atrophies with age- composed of cortex and medulla- medulla contains Hassalls corpuscles (thymic corpuscles)

    Differs from other lymphoid organs- functions strictly in lymphocyte maturation- arises from epithelial tissue

  • ThymusFigure 20.11

  • Lymph NodesFunctional pathway

    Lymph percolates through lymph sinuses

    Most antigenic challenges occur in lymph nodes

    Antigens destroyed activate B and T lymphocytes

  • SpleenLargest lymphoid organ

    Two main blood-cleansing functionsRemoval of blood-borne antigensRemoval and destruction of old or defective blood cells

    Site of hematopoiesis in the fetus

  • SpleenDestruction of antigens

    Site of B cell maturation into plasma cells

    Phagocytosis of bacteria and worn-out RBCs, WBCs and platelets

    Storage of platelets

  • White pulp thick sleeves of lymphoid tissue

    Red pulp - surrounds white pulp- composed of venous sinuses - splenic cords

  • SpleenFigure 20.12

  • TonsilsSimplest lymphoid organs

    Four groups of tonsilspalatine, lingual, pharyngeal, and tubal tonsils

    Arranged in a ring to gather and remove pathogens

    Underlying lamina propria consists of MALT

  • Palatine TonsilFigure 20.13

  • Aggregated Lymphoid Nodules and AppendixMALT abundant in walls of intestines

    Fight invading bacteria

    Generate a wide variety of memory lymphocytes- aggregated lymphoid nodules (Peyers patches)- located in the distal part of the small intestine Appendix tubular offshoot of the cecum

  • Aggregated Lymphoid NoduleFigure 20.14

  • LymphomaNeoplasm (tumor/abnormal growth) in the lymph tissue. Two types: Hodgkins disease or non-Hodgkins disease.

  • Hodgkins DiseaseMalignant lymphoma which has been linked to viral infections such as EBV (Epstein-Barr virus {mono}), HIV, and exposure to wood and wood products.Most often occurs in young adults.Most common symptom is painless, swelling of the lymph nodes in the neck, armpit, or groin. Other symptoms include fatigue, unexplained fever, night sweats, and indigestion.

  • Hodgkins DiseaseDiagnosisOften shows up on a CAT scan.Confirmed by biopsy.Treatment usually includes chemotherapy and radiation.

  • Non-Hodgkins LymphomaPatients with HIV/AIDS or those who have received immune suppressive therapy are at higher risk for developing non-Hodkins lymphoma. Same presenting symptoms as Hodgkins and treatment is similar.

  • ChemotherapyWorks by killing fast-growing cancer cells. Unfortunately, chemo can't always tell the difference between cancer cells and fast-growing healthy cells, including RBCs and WBCs.

  • ChemotherapyNurses will wear special gloves and gowns when preparing and giving you chemotherapy drugs. Additionally, pharmacists prepare the drugs in areas with special ventilation systems. Special procedures are used for disposing of materials after mixing and administrating the drugs. There are separate plastic containers to dispose of sharp items, syringes, IV tubing and medication bags.

  • Radiation Cancer treatment that uses high doses of radiation to kill cancer cells and stop them from spreading.

  • ImmunityThe ability of the body to defend itself against infectious agents, foreign cells, and even abnormal body cells, such as cancer.Immunity can be acquired, like when you get chicken pox and then you are protected from getting it again.Immunity can be artificially acquired like when you get a vaccination.

  • Nonspecific ImmunityInnate-you are born with it.Provides immediate and general protection against invaders.

  • Nonspecific ImmunityPhysical and chemical barriers: Intact skin is a physical barrierSkin also produ