Lymphatic system

Lymph - excess tissue fluid carried by lymphatic vessels, this fluid was pushed out of the capillary beds and into tissue spaces.

Lymphatic vessels - one way system toward the heart.

Lymph moves toward the heart only : a. milking action of skeletal muscle. b. rhythmic contraction of smooth muscle in vessel walls c. respiratory pump - pressure changes within the thorax.

Lymph node structure - fibrous capsule, trabeculae, cortex, follicles, germinal centers, plasma cells, medulla

Fibrous capsule - surrounds the lymph node

trabeculae - extend from the capsule dividing the node into compartments

Cortex - outer part, contains follicles with dark centers called germinal centers that enlarge when generating plasma cells which release antibodies, rest of cortex contains T-cells that continuously circulate between blood, lymph nodes, lymphatic stream performing their surveillance role

Medulla - inner part, contains phagocytic macrophages

Several other organs contribute to lymphatic function - spleen, thymus gland, tonsils, peyer’s patches

Nonspecific (innate) body defenses - skin and mucous membranes, stomach mucosa, saliva and lacrimal fluid

sebum is toxic to bacteria

stomach mucosa - secretes hydrochloric acid (HCI) and has protein digesting enzymes

saliva and lacrimal fluid - contain lysozymes (enzymes that destroy bacteria)

Cells and chemicals (second line of defense) - phagocytes, natural killer cells, inflammatory response, antimicrobial proteins, interferon, fever

four most common indicators of acute inflammation - redness, heat, swelling, and pain

Hypothalamus heat regulation can be reset by pyrogens - secreted by white blood cells especially macrophages that have been exposed to pathogens

Specific (adaptive) defense system - immune response is the immune systems response to a threat, much slower than non specific system

Macrophages - help lymphocytes, “big eaters” that engulf any foreign particles (arise for monocytes and become widely distributed in lymphoid organs, secrete cytokines, tend to remain foxed in the lymphoid organs, antigen presenters, some become “killer macrophages” when activated by a chemical form T cells and become insatiable phagocytes

some B cells become long lived memory cells for secondary humoral response, “immunological memory” for that specific antigen

Active immunity - naturally acquired, artificially acquired from vaccines

Passive immunity - conferred naturally from a mother to her fetus, conferred artificially from immune serum or gamma globulin (anti toxin, anti venom)

Antibody classes - IgM, IgA, IgD, IgG, IgE