These selected cells then proliferate forming a clone

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Unformatted text preview: against the constant barrage of pathogens. ! First of the three lines are external barriers. Second line of defense is internal protecDons. Both of these are known as the innate defenses. The third line of protecDon is the adap.ve defenses. ! “Once within the body fluids and Dssues, the invader is no longer an outsider.” ! External innate defenses include these such as beaDng cilia extending from the cells of the respiratory tract that sweep mucus with the trapped parDcles outward unDl it is swallowed or expelled by sneezing. Mucus membrane linings in organs that are open to external environment, such as the respiratory, digesDve, reproducDve, and urinary systems, help trap bacteria, dust, and other parDcles. ! Internal innate defenses, second line of defense consists mainly of white blood cells and defensive proteins. ! Two types of blood cells involved in internal innate defense: phagocy.c cells and natural killer cells. ! Interferon(s), produced by virus- infected body cells, work indirectly by helping healthy cells resist damage by viral infecDon. ! Virus infected cells (1) make and release interferons that (2) bind to plasma membrane receptors on nearby uninfected cells. This binding sDmulates healthy cells to (3) produce proteins that inhibit viral reproducDon. ! Complement proteins aMack pathogens directly. ! Inflammatory response is another example of internal innate defenses. ! Histamine is triggered; this dilates the blood vessels and leak fluid into the wounded Dssue. ! Innate defenses are ready in the body without any preparaDon. ! “The two main funcDons of the lympha.c system are to return Dssue fluid to the circulatory system and to fight infecDon.” “When your body is fighDng an infecDon, the lymphaDc system is the main baMleground.” ! As the lymph passes through the lymphaDc Dssue, phagocy.c cells engulf invaders. ! Adap.ve defenses are acDvated only ager exposure to specific pathogens. ! AdapDve defenses depend on lymphocytes to recognize and respond to specific invading pathogens. ! Two types of lymphocytes are B cells and T cells. ! B cells develop and mature in the bone marrow. T cells migrate via blood to thymus, a gland in the chest, where they become specialized. Both types of cells eventually make their way to the lymph nodes and other lymphaDc organs. ! Any...
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This document was uploaded on 03/02/2014 for the course BIO 101 at University of Tennessee.

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