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Blood
BLOODEssence of lifeUncontrolled loss can  lead to deathHas  magical qualitiesThought to define our character and emotionsBlue blood ⎯  people with noble bloodline“bad” blood ⎯ criminalsAnger causes blood to  “boil”Fear makes it “curdle”Performs many functions essential  to  life and reveal much about our healthBlood  maintains homeostasis in several ways8% of total body weightFUNCTIONSTransport of gases, nutrients and waste productsOxygen enters the blood in the lungs and is carried to cells(Oxygen → blood in lungs → cells)CO2 , produced by cells is carried in the blood to lungs, from which it is expelled  (CO2 in cells→blood→lungs)Transports ingested nutrients, ions, and water from the digestive tract to cellsTransports waste products of cells to the kidneys for eliminationTransport of processed moleculesMany substances are produced in one part of the body and transported in the blood to another part,  where they are modifiedVitamin DProduced in the skinTransported by blood → liver→  kidneys (processing into active vit. D)Blood transports active vit. D to small intestine (promotes uptake of calcium)LactateProduced by skeletal muscles (anaerobic respiration)Blood carries lactate to the liver (lactate→glucose)Transport of regulatory moleculesBlood carries many of the hormones and enzymeshormones and enzymesregulate body processes from one part of the body to anotherRegulation of pH and osmosisBuffers  ⎯ help maintain blood’s pH within its normal limits of 7.35-7.45Osmotic composition ⎯ critical for maintaining normal fluid and ion balanceMaintenance of body temperatureWarm bloodTransported from the interior of the body to the surface (heat is released from the blood)One of the mechanisms that help regulate body temperatureProtection against foreign substancesCertain cells and chemicals in the blood constitute an important part of the immune systemProtects against foreign substances such as microorganisms and toxins Clot formationWhen blood vessels are damaged, blood clotting protects against excessive blood lossWhen tissues are damaged, the blood clot that forms is also the first step in tissue repair and restoration of normal functionCOMPOSITION OF BLOODPLASMALiquid matrix containing cells and cell fragmentsSlightly more than half  of total blood volumeFORMED ELEMENTSCell  and cell fragmentsSlightly less  than half of total  blood volumeTotal blood volume: 5-6 L (M);                       4-5 L (F)PLASMAPale yellow fluid that consists of about 91% water, 7% proteins and 2% other components (ions, nutrients, gases, waste products and regulatory substances)Contains dissolved proteinsInclude albumin, globulins, and fibrinogenAlbumin58% of plasma proteinsMakes an important contribution in the osmotic pressure of bloodGlobulins38% of plasma proteinsE.g.  antibodies and complement are part of the immune systemOther globulins and albumin function as  transport molecules because they bind to hormones and carry them in the blood throughout the bodySome are Clotting factors  ⎯ necessary for formation of  blood clotsFibrinogenClotting factor (4% of plasma proteins)Activation of clotting factors ⎯ convert fibrinogen to fibrils (threadlike proteins that form blood clots       SerumPlasma without clotting factorsFORMED ELEMENTS95% erythrocytes/red blood cells5%  leukocytes/white blood cells and platelets/thromobocytes(cell fragments)RBC 700x more numerous than WBCRBC 17x more numerous than plateletsPRODUCTION OF FORMED ELEMENTSHematopoiesis ⎯ Blood cell production⎯ In the fetus, occurs in several tissues:LiverThymusSpleenLymph nodesRed bone marrow        ⎯ After birth hematopoiesis is confined primarily to red bone marrow with some WBC produced in lymphatic tissuesStem cells/hemocytoblastsSingle population of cells where all  formed elements are derivedDifferentiate to give rise to different cell lines, each of which ends with the formation of a particular type of formed elementGrowth factors determine the types of formed elements derived from stem cells determine number of formed elements produced