Chapter 22 - Overview of the Lymphoid System - Chapter 22 -...

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Chapter 22 - Overview of the Lymphoid SystemPathogens are microscopic organisms that cause disease; each attacks in a specific way Viruses, Bacteria, Fungi & ParasitesLymphoid Systemprotects us against disease; cells respond to: environmental pathogens, toxins & abnormal body cells, such as cancers Specific Defenses: lymphocytes; part of immune response; identify, attack & develop immunity to a specific pathogenThe Immune System0.Immunity - the ability to resist infection and disease 1.All body cells and tissues involved in production of immunity, not just lymphoid system Nonspecific Defensesblock/attack any potential infectious organism but can’t distinguish Organization of the Lymphoid Systemi.Lymph -a fluid similar to plasma but does not have plasma proteinsii.Lymphatic vessels (lymphatics) -carries lymph from peripheral tissues to venous systemiii.Lymphoid tissuesandlymphoid organsiv.Lymphocytes, phagocytes,andother immune system cellsFunction of the Lymphoid System -to produce, maintain & distribute lymphocytesStructures of Body Defenses: Lymphocyte ProductionLymphocytes are produced in lymphoid tissues (tonsils), lymphoid organs (spleen, thymus) & in red bone marrow; Lymphocyte detects problems by traveling into site of injury/infectionLymphocytes circulates blood (capillaries)interstitial fluid venous blood (lymph vessels)Lymph = interstitial fluid that has entered a lymphaticCirculation of Fluidsblood  lymph & back transports hormones, nutrients & waste productsLymphatic Vessels:vessels that carry lymph; lymphoid system starts with smallest vesselsLymphatic capillaries:they differ from blood capillaries in 4 ways: start as pockets rather than tubes; have larger diameters; have thinner walls; flat or irregular in sectionLymphatic Capillaries: endothelial cells loosely bound together with overlap; overlap acts as 1-way valve & allows fluids, solutes, viruses & bacteria to enter & prevents their return Lymph flowsfrom lymph capillaries to larger vessels containing 1-way valves; they travel with veinsLactealsare special lymphatic capillaries in small intestine; transport lipids from digestive tractLymphatic vesselsare in skin, mucous membranes & serous membranes lining body cavities Smaller lymphatics join to form large lymphatic trunks that empty into 2 major collecting vessels: 0.thoracic duct – empties into left subclavian vein1.

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Term
Fall
Professor
WATSON
Tags
Physiology, Human Anatomy, Bacteria, Fungi, Viruses, cells, T Cells, helper t cells

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