Chapter 14: The Lymphatic System Flashcards
lymph
fluid that flows through lymphatic vessels; resembles plasma but contains much lower concentration of suspended proteins
afferent lymphatic vessels
deliver lymph to a lymph node
efferent lymphatic vessels
carry lymph away from lymph nodes toward venous system
Lymphocytes
specialized cells that perform an array of specific functions in bodily defense account for 25% of circulating WBCs
EX: T cells, B cells, NK cells
T cells
-Thymus-dependent
-make up ~80% of circulating lymphocytes
-divided into cytotoxic (killer), helper, suppressor, and memory
- provide cell-mediated (cellular) immunity (defend inside living cells)
complement system (cascade)
-complements the actions of antibodies
(complement Binds to antibody or bacterial cell wall)
-attracts phagocytes
-enhances phagocytosis
-destroys cell membranes
-promotes inflammatory response
B cells
-Bone marrow-derived
-make up ~10-15% of circulating lymphocytes
-responsible for antibody-mediated immunity (defend in body fluid)
-sensitized when antigens enter cell
antigens
A substance capable of inducing the production of antibodies
NK cells
-natural killer cells
-make up ~10-15% of circulating lymphocytes
-respond much more rapidly than T or B cells
-attack foreign cells, normal cells infected with viruses, and cancer cells in normal tissues
-continual monitoring is known as immunological surveillance
Functions of the lymphatic system
-production, maintenance, distribution of lymphocytes
-return of fluids from peripheral tissues to the blood
-distribution of hormones, nutrients, and waste products from peripheral tissues to blood
specific Defenses
(Specific resistance or immunity) is provided by the coordinated activities of T cells and B cells which respond to the presence of specific atigens.
phagocytes
remove cellular debris and pathogens and respond to invasion by foreign compounds or pathogens represent “first line” of cellular defense
neutrophils
50-70% of circulating WBCs; granules are chemically neutralusually the first WBC to arrive at an injury siteactive phagocytes; specialize in attacking bacteria
eosinophils
2-4% of circulating WBCs; stain from red dye = “eosin”attack antibody-labeled materials through release of cytotoxic enzymes and/or phagocytosisnumbers increase dramatically during parasitic infection
four components of lymphatic system
lymphocytes, lymphoid tissues, fluid (“lymph”), vessels
lymphoid tissues
collections of loose connective tissue and lymphocytes in structures called lymphoid nodules
helper T cells
Stimulate both T and B Cells and Coordinate specific/non-specific defenses by stimulating cell-antibody mediated activity
suppressor T cells
act after initial response to dampen/”put brakes on” immune response activated more slowly than other T cells
regulatory T cells
helper and suppressor T cells
lymph nodes
-located in groin (inguinal), armpit (axillary), neck/face (cervical), lumbar area
-purify lymph before it enters venous system
-swollen glands often accompany infection
memory B cells
remain in reserve to respond to subsequent exposure to the same antigen; at which time they differentiate into antibody-secreting plasma cells
thymus
lies in the mediastinum posterior to the sternum
site of T cell production and maturation
IgM
first antibody type secreted following arrival of antigen; levels decline as IgG production accelerate sresponsible for cross-reactions between incompatible blood types
IgA
found in glandular secretions (tears/mucus/saliva) attack pathogens before they enter the body tissues
