Blood 16

Composition of Blood Figure 16-1 (1 of 2)

Cellular Elements Three main cellular elements Platelets split off from megakaryocyte Five types of mature white blood cells Monocytes develop into macrophages Tissue basophils are mast cells Neutrophils, monocytes and macrophages are known as phagocytes Lymphocytes are also called immunocytes Basophils, eosinophils and neutrophils are also called granulocytes

Composition of Blood Found in lymphatic system, B- & T-cells Exit blood stream to become macrophages & APC Phagocyte for bacteria & secretes cytokines (ex. signal fever) Phagocyte for parasites & cytokines related to allergies Mediate inflamation& allegies via cytokine release (histamine) Figure 16-1 (2 of 2)

Hematopoiesis Signaled by erythropoeitin, a hormone released by the kidneys in response to low O2, Or by thrombopoetin, colony-stimulating factors, interleukin, & stem cell factor Figure 16-2

Focus on … Bone Marrow Blood production in adults is limited to the axial skeleton, the humerus,a nd femur. Figure 16-4a

Focus on … Bone Marrow Overall components of bone marrow include the stroma & sinus capillary. Notice the platelet, RBC, and Neutrophil formation Platelets Reticulocyte expelling nucleus Stem cell Lymphocyte Venous sinus Monocyte Reticular cell Stem cell Reticular fiber (c) Mature blood cells squeeze through the endothelium to reach the circulation. Fragments of megakaryocyte break off to become platelets. The stroma is composed of fibroblast-like reticular cells, collagenous fibers, and extracellular matrix. Macrophage Mature neutrophil Red blood cell maturation Neutrophil maturation Figure 16-4c

Erythrocytes Transport oxygen and carbon dioxide. Originate in bone marrow and as they mature they expel their organelles before entering the blood stream. Most numerous component of formed elements. Contain no nucleus or organelles, instead they are packed with hemoglobin. There are three important characteristics of red blood cells: 1. Their concave shape allows for 30% more surface area for carrying oxygen. 2. 97% of their content is hemoglobin. It is used for binding both oxygen & CO2 3. They depend on anaerobic respiration thus they do not consume any oxygen

Osmotic Changes to Red Blood Cells Morphology of red blood cells can provide clues to the presence of disease. Diagram shows cells in solutions of different salt concentrations. However, some disorders do are due to abnormal RBC shape. Figure 16-6

Sickled Red Blood Cells A single genetic mutation error in one amino acids produces a proteins with an irregular shape causing many problems Figure 16-8

Iron Metabolism Normally the body stores iron but women need to consume more iron than men. Why? Figure 16-7

Red Blood Cells Live for about 120 days- old cells get broken at the spleen or cleared by macrophages Hemoglobin components are recycled- iron is reused to make new hemoglobin Remnants of heme groups – the other components are taken to the liver and become components of bile Bilirubin is excreted in bile and gives bile its green color Jaundice- yellowing of the skin, nail, and sclera in eyes due to elevated blood levels of bilirubin resulting form liver malfunction.

Hemostasis (not homeostasis) Keeps blood within blood vessels (hemorrhage does not) Requires: 1- vasoconstriction, 2- platelet plug formation, 3- blood coagulation (seal hole) Coagulation cascade results in formation of fibrin, a fiber mesh that stabilizes the platelet plug=clot Plasmin is an enzyme that dissolves the clot as the tissue heals A thrombus results from too much clot formation and can block a blood vessel

Platelet Plug Formation Figure 16-11

Overview of Hemostasis and Tissue Repair Diagram displays the mechanisms for restoring broken blood vessels Damage to wall of blood vessel Tissue factor exposed Intact blood vessel wall Reinforced platelet plug (clot) Fibrin slowly dissolved by plasmin Clot dissolves Collagen Platelets aggregate into loose platelet plug Temporary hemostasis Cell growth and tissue repair Vasoconstriction Platelets adhere and release platelet factors Thrombin formation Coagulation cascade Converts fibrinogen to fibrin Figure 16-10

The Coagulation Cascade Intrinsic Pathway begins when collagen is exposed Extrinsic pathway is activated by damaged tissues Thrombin is need to created fibrin- the insoluble fibers create the clot. Positive feedback loops remain until a component is consumed Figure 16-12

Coagulation and Fibrinolysis Clot formation is limited to prevent the entire blood content from coagulating. Figure 16-13

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Rh antigens and antibodies Blood Types Antigens on RBCs A, B, AB or none (O) Antibodies in plasma Anti A, anti B, anti AB Rh antigens and antibodies