BSCI202 EXAM 1 REVIEW LYMPHATIC AND IMMUNE I Lymphatic System a Consists of two parts Know components characteristics and function i Lymphatic vessels ii Lymphoid tissues and organs b Functions i Transports escaped fluids back to the blood ii Plays essential roles in body defense and resistance to disease iii Also has a role in digestion helps fat be absorbed lacteals iv Collect excess fluid and lymph nodes clean interstitial fluid which is basically plasma v Anything below your heart runs upward c Developmental Aspects of Lymphatic System and Body Defenses i Except for thymus and spleen lymphoid organs are poorly developed after birth ii Newborn has no functioning lymphocytes at birth only passive immunity iii from mother If lymphatics are removed or lost severe edema results but vessels may grow back in time iv Cancer metastasizes near the lymphs d Central Lymphoid Tissue i Bone marrow thymus central lymphoid tissue ii Bone marrow iii Thymus 1 Hematopoietic stem cells precursor for all blood cells 2 Leukocytes except T lymphocytes fully develop here 1 T lymphocytes migrate from bone marrow to thymus 2 Develop maturity in thymus e Peripheral Lymphoid Tissue i Spleen lymph nodes tonsils adenoid appendix Peyer s patches ii Collections of B cells T cells and macrophages iii Function to trap microorganisms and foreign particles iv Works to expose them to leukocytes in high concentrations v Spleen and lymph nodes filter blood and lymph vi Lymph nodes swell when you re sick because filled with WBCs and if more WBCs then that means an infection II Lymphoid Organs that Contribute to Lymphatic Function a Spleen i Located on the left side of the abdomen ii Filters blood and destroys worn out blood cells iii Forms blood cells in the fetus iv Acts as a blood reservoir b Thymus i Located low in the throat overlying the heart ii Functions at peak levels only during childhood iii Produces hormones like thymosin to program lymphocytes iv Acting during childhood to help keep you alive but by young adulthood you re fine and it shrinks and turns to fat now we get vaccinations because our thymus isn t big anymore or really useful c Tonsils i Masses of lymphoid tissue around the pharynx ii Trap and remove bacteria and other foreign materials iii Tonsillitis is caused by congestion with bacteria iv Have high amounts of WBCs i Found in the wall of the small intestine capture and destroy bacteria in the d Peyer s Patches intestine e Lymph Nodes i Filters lymph fluid before it is returned to the blood lymph fluid was interstitial fluid which was blood ii Defense cells within lymph nodes 1 Macrophages engulf and destroy foreign substances 2 Lymphocytes provide immune response to antigens iii Some harmful materials that may enter lymph vessels 1 Bacteria 2 Viruses 3 Cancer cells 4 Cell debris 5 Protists 6 Worms 7 Fungi iv Non selective v Structure 1 Most are kidney shaped and less than 1 inch long 2 Cortex a Outer part b Contains follicles that house collections of lymphocytes 3 Medulla Inner part a b Contains phagocytic macrophages 4 Hilum indentation 5 Afferent and efferent vessels more afferent because want fluid to be super filtered slowly III Lymphatic Characteristics a Lymph fluid carried by lymphatic vessels b Properties of lymphatic vessels i One way system toward the heart ii No pump iii Lymph moves toward the heart 1 Squeezing motion of skeletal muscle 2 Rhythmic contraction of smooth muscle in vessel walls 3 Moving helps lymph move c Problems i Elephantiasis ii Filariasis transmitted by mosquito worms evades immune system and goes to lymph and reproduces only way to remove infection is to remove tissue 1 Mosquito takes a blood meal larvae enter skin 2 Adult worms in lymphatics 3 Adults produce sheathed microfilariae that reach the blood stream 4 Mosquito takes a blood meal ingests microfilariae 5 Microfilariae shed sheaths penetrate mosquito s midgut and migrate to thoracic muscles 6 L1 Larvae 7 L3 Larvae 8 Migrate to head and mosquito s proboscis IV Lymphatic Vessels a Flow of Lymph Through Nodes i Lymph enters the convex side through afferent lymphatic vessels ii Lymph flows through a number of sinuses inside the node sinuses cavities iii Lymph exits through efferent lymphatic vessels iv Fewer efferent than afferent vessels causes flow to be slowed v As fluid leaks out of capillary it gets pushed into lymph vessels vi Lymph vessels just open and close letting in fluid b Lymph Capillaries i Walls overlap to form flap like mini valves ii Fluid leaks into lymph capillaries iii Capillaries are anchored to connective tissue by filaments iv Higher pressure on the inside closes mini valves v Fluid is forced along the vessel c Lymphatic Collecting Vessels i Collect lymph from lymph capillaries ii Carry lymph to and away from lymph nodes iii Return fluid to circulatory veins near the heart 1 Right lymphatic duct 2 Thoracic duct Body s Response to a Cold Virus a Virus is breathed into the lungs b Virus infects cells that line lungs and breathing passages c At the same time viruses bind to mast cells and causes the release of histamine d Histamine binds to blood vessels causing them to leak cells and fluid causing inflammation e Macrophage digests virus and displays viral antigens f Antigen presenting macrophage travels via lymphatic system to lymph node g Cells in lymph nodes produce antibodies h Antibodies travel via blood back to lungs attack virus Immune System a Body Defenses V VI i The body is constantly in contact with protists bacteria fungi and viruses ii Body has two defense systems for foreign materials how do they work together to maintain homeostasis 1 Innate defense system non specific defense system a Mechanisms protect against a variety of invaders b Responds immediately to protect body from foreign materials 2 Adaptive defense system specific defense system a Specific defense is required for each type of invader iii We can develop immunity or specific resistance to certain pathogens b 3 Lines of Defense i Innate nonspecific defense mechanisms 1 First line of defense a Skin forms mechanical barrier that prevents entry of pathogens and other harmful substances into body i Acid mantle skin secretions make epidermal surface acidic which inhibits bacterial growth sebum also contains bacteria killing chemicals ii Keratin Provides resistance against acids alkalosis and bacterial enzymes b Mucous membranes form mechanical barrier that prevents entry of pathogens i Mucus Traps microorganisms
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