Ch 30

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mwebb01
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173097
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Ch 30
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2012-09-25 21:06:00
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Hematologic System
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Hematologic System
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  1. Hematology
    • the study of blood and blood forming tissues
    • (bone marrow, blood, spleen. and lymph system)
    • helpful in evaluating pt's ability to transport O2 and C02, coagulate blood, and combat infection
  2. Bone marrow - where blood cells are produced - soft material that fillss the central core of bones
    • two types:
    • yellow - adipose
    • red - hematopoietic - (what produces blood cells) found primarily in flat and irregular bones - i.e. end of long bones, pelvic bones, vertebre, sacrum, sternum, ribs, flat cranial bones, scapulae
  3. All blood cells (RBC's, WBC's, and platelets) develop from:
    a hematopoietic stem cell (a non differentiated immature blood cell found in the bone marrow)
  4. Blood is responsible for 3 major functions:
    • transportation- of oxygen, nutrients, hormones, waste products
    • regulation - of fluid, electrolyte, and acid-base balance
    • protective - ability to clot and combat infections
  5. Two major components of blood
    • Plasma - ~55% of blood is plasma, mainly water, contains gases, proteins, electrolytes, nutrients, waste.
    • (serum - is plasma minus the clotting factors)
    • Blood cells - ~45% of the blood, (RBC's, WBC's, and platelets)
  6. erythrocytes
    • Primary function - transport gases (02 and CO2) and assist with acid-base balance
    • made up of - primarily Hemoglobin- functions to  bind with O2 and CO2. O2 binds with the iron ("heme") portion of Hgb and CO2 binds with the protein ("globin"); also plays role in acid-base balance
    • life span - 120 days
  7. leukocytes
    • function - protect from infection
    • different types that have different functions
    • two categories - granulocytes and agranulocytes
    • granulocytes - contain granules within the cytoplasm - neutrophils, basophils, eosinophils
    • agranulocytes - do not contain granules within the cytoplasm - lymphocytes, monocytes
  8. primary function pf platelets
    promote blood coagulation (clotting)
  9. erythopoiesis
    • Production of RBCs
    • regulated by 02 requirememts and general metabolic activity; also influenced by available nutrients (essential nutrients for  erthropoiesis - protein, iron, folate - "folic acid, cobalamin -"vit B12", riboflavin -"vitB2" pyridoxine -"vitB6"; also by endocrine hormones - thyroxine, corticosteriods, testosterone
    • stimulated by hypoxia
    • controlled by erythropoietin - which is synthesized and released by the kidneys; it stimulates bone marrow to increase erythrocyte production
  10. immature erythrocyte
    reticulocyte - can develop into mature RBC within 48hrs; assessing the # of reticulocytes is useful in evaluating the rate and adequacy of erythrocyte production
  11. destruction of RBCs
    hemolysis- monocytes and macrophages remove abnormal, defective, damaged, and old RBCs; occurs in bone marrow, liver, and spleen; causes increased bilirubin to be processed
  12. Granulocytes
    • type of leukocyte - neutrophils, basophils, and eosinophils
    • primary function - phagocytosis - ingest, digest and kill unwanted organisms
  13. neutrophil
    most common type of granulocyte (50-70% of all WBC's), primary phagocytic cell involved in acute inflammatory responses; production is stimulated by hematopoietic growth factors; mature neutrophils - "segmented neutrophils"; immature neutrophils - "bands"
  14. eosinophils
    • granulocyte (2-4% of all WBCs)
    • phagocytosis ability
    • primary function - engulf antigen-antibody complexes formed during an allergic response; also defend against parasitic infections
  15. basophils
    • granulocyte (less than 2% of all WBCs)
    • phagocytic ability
    • contains heparin, serotonin, and histamine - if cell is stimulated - it releases these substances - this is seen when basophils are stimulated by an antigen or tissue injury. this is part of the response seen inallergic and inflammatory reactions
  16. lymphocytes
    • agranulocyte (20-40% of all WBCs)
    • primary function - related to immune response; form basis of celluar and humoral  immune response
    • subtypes - B cells (mature in bone marrow) and T cells (migrate to thymus gland for further differentiation)
  17. monocytes
    • agranulocyte (4-8% of all WBCs)
    • potent phagocytic cells
    • 2nd type of WBC to arrive at scene of injury
    • present if blood for short time before becoming macrophages - which protect body from pathogens and are even more potent phagocytic than monocytes; they also interact with lyphocytes to facilitate humoral and cellular immune responses
  18. thrombocytes
    • "platelets"
    • primary function - initiate the clotting process by producing an initial platelet plug in the early phass of the clotting process; maintain capilary integrity by working as "plugs" to close any openings in the capillary wall; also inportant in clot shrinkage and retraction
    • the stem cell transforms into a megakaryocyte which produces platelets
    • regulated partly by thrombopoietin - acts on bone marrow to stimulate platelet production - produced in the liver, kidneys, smooth muscle, and bone marrow
    • life span: 5-9 days
  19. Iron metabolism
    • only 5-10% if ingested iron is absorbed
    • present in all RBCs and heme in hemoglobin and in a stored form (ferritin and hemosiderin) in the bone marrow, spleem, liver, and macrophages
    • Transferrin - synthesized by the liver - a carrier plasma protein for iron - the degree of transferrin saturation indicates iron supply for developing RBCs
    • iron is recycled once macrophages in the liver and spleen phagocytize old and damaged RBCs
  20. hemostasis is what?
    what are the 4 components that contribute to normal hemostasis?
    • -blood clotting process
    • -vacular response, platelet plug formation, development of the fibrin clot on the platelet plug by plasma clotting factors, and ultimate lysis of the clot
  21. hemostasis - vascular response
    immediate vasoconstriction - to reduce leakage of blood
  22. hemostasis - platelet plug formation
    • the platelet response and plasma clotting factors are triggered by endothelial injury and release of substances such as tissue factor (TF)
    • platelets are activated when they are exposed to interstitial collagen from an injured blood vessel
    • platelets stick together  - adhesiveness" and form clumps "aggregation/agglutination"
  23. hemostasis - fibrin clot development on the platelet plug by plasma clotting factors
    • the fibrin clot is the results of series of reactions of clotting factors
    • Thrombin (most powerful enzyme in the coagulation process) - converts fibrinogen into fibrin (an essential component of a blood clot)
  24. hemostasis - lysis of clot
    • antithrombins - keep blood in fluid state  by antagonizing thrombin - protein C and S and heparin are examples of anticoagulants
    • fibrinolysis - dissolution of the fibrin clots - this system is initiated when plasminogen is activated to plasmin by thrombin. Plasmin attacks fibrin/fibrinogen by splitting them up into smaller elements (fibrin split products FSPs/FDPs); if this is excessive person is prone to bleeding 
  25. 4 major functions of the Spleen
    • hematopoeitic- able to produce RBCs during fetal development
    • filtration- able to remove old, defective RBCs; reuses iron from hemolysis
    • immunologic- filters circulating bacteria, has rich supply of lymphocytes, monocytes, and immunoglobulins
    • storage- storage site for RBCs and platelets (splenectomy - results in higher # of circulating platelets)
  26. Lymph system
    • consists of lymph fluid, lymphatic capillaries, ducts, and lymph nodes- carry fluid from the interstitial spaces of the blood
    • returns proteins, fats, hormones, and excess interstitial fluid to the circulatory system
    • lymph fluid production is increased when interstitial fluid increases - when too much develops or interference with reabsorption occurs - lymphedema develops
  27. Liver
    functions as filter, produces all procoagulants (essential for hemostasis and blood coagulation), stores excess iron (regulator of iron produced by liver - hepcidin- reduces release of iron from RBCs)
  28. effects of aging on hematologic system
    • Red marrow and stem cells decrease
    • marrow space occupied by hematopoietic tissue declines
    • reserve capacity decreases - more vunerable to problems with clotting, O2 transport, fighting infection (esp during increased demand)
    • Hgb levels decrease (low normals seen in older adults)
    • iron deficiency due to decreased intake is usually responsible for low Hgb levels (but should assess for other disease processes like GI bleeding)
    • decreased ability to produce reticulocytes in response to hemorrhage or hypoxia than when younger
    • RBCs are more fragile causing increased MCV and decreased MCHC
    • WBC's - unchanged but humoral antibody response and T cell function is decreased - causing only minimal elevation in total WBC count
    • Platelets - unaffected but changes in vacular integrity causes easy bruising
  29. Assessment of Hematologic System - Hx -
    problems with anemia, bleeding disorders, blood diseases; malabsorption; liver, kidney, spleen disorders
  30. Assessment of Hematologic System - medications -
    complete med list including use of vitamins, herbal products, dietary supplements (see Table 30-5 p649)
  31. Assessment of Hematologic System - Surgical or other tx
    splenectomy, tumor removal, prosthetic heart valve placement, surgical excision of duodenum (where iron absorption occurs), partial or total gastrectomy (which removes parietal cells, thus reducing intrinsic factor needed for absorption of cobalamin), gastric bypass (where the duodenum may be bypassed and parietal cell surface area decreased), ileal resection (where cobalamin absorption takes place); how wound healing progressed, any bleeding problems afterwards, previous blood transfusions
  32. Assessment of Hematologic System - health perception/mgmt pattern
    age, gender, race, ethnicity; risk factors- alcohol use- damages GI tract and causes bleeding, esophageal varices, decreased absorption of cobalamin; cigarette use- increases LDL and CO2 leading to hypoxia and altering the anticoagulant properties of the endothelium, increases platelet reactivity, plasma fibrinogen, hematocrit, and blood viscosity
  33. Assessment of Hematologic System - nutritional-metabolic pattern
    obtain weight, assess s&s of N/V, oral discomfort, diet hx- clues to causes of anemia, bleeding gums, any petechiae or ecchymosis (decreased platelets), lumps or swelling in lymph node areas (neck armpits groin), cardiac/pulmonary diseases (or meds that treat such)- HTN, valvular diseases can cause hemolysis, or can lead to hypoxemia leading to polycythemia
  34. Assessment of Hematologic System - elimination pattern
    blood in stool/urine, black tarry stools, decreases in urinary output, diarrhea
  35. Assessment of Hematologic System - Activity/exercise
    fatigue: prominent symptom in many hematologic disorders, tiredness, heavy extremities, change in ability to perform ADLs
  36. Assessment of Hematologic System - sleep/rest
    fatigue due to hematologic disorders is NOT releived by sleep
  37. Assessment of Hematologic System - cognitive/perceptual
    joint pain (autoimmune disorders), aching bones (leukemias), parasthesia, numbness, tingling, change in vision, hearing, taste, mental status
  38. Assessment of Hematologic System - other
    environmental exposure to radiation/chemicals, menstrual hx, child birthing issues, problems with impotence, sexual behavior (bc of HIV), support systems, belief systems
  39. Assessment of Hematologic System - Physical exam
    • specifically relevant areas - skin, lymph nodes, spleen, liver
    • lymph nodes- assess symetrically with regard to location, size, , fixation, tenderness, texture (should be: not palpable or small - 0.5-1cm, mobile, firm, and nontender); hard/fixed-malignancy; tender-inflammation
    • liver, spleen- palpation and percussion
    • skin: RBC discorders- pale, pasty, or cyanotic in severe anemia; erythrocytosis- mottled appearance; chronic anemia- clubbing; WBC disorders- lesions; bleeding disorders- petichiae, ecchymosis, spider nevus (skin and mucosal bleeding - platelet disorder; spontaneous bleeding into joints or muscles - coagulation factor problem)
    • heart- palpitations, tachycardia
  40. entire suppression of CBC; marked decrease in RBCs, WBCs, and platelets
    • pancytopenia
    • tx: mgmt of anemia, infection, and hemorrhage
  41. Total RBC count
    • count of number of circulating RBCs
    • female: 3.8-5.1 x 10^12/L
    • male: 4.3-5.7 x 10^12/L
    • reduced in anemia, hemorrhage, hemodilution like hypervolemia (same for Hgb and Hct)
    • increased in polycythemia, hemoconcentration like dehydration (same for Hgb and Hct)
  42. Hemoglobin (Hgb)
    • measures gas-carrying capacity of RBC
    • female: 11.7-16g/dL
    • male: 13.2-17.3 g/dL
    • reduced in anemia, hemorrhage, hemodilution like hypervolemia (same for Hct and total RBC count)
    • increased in polycythemia, hemoconcentration like dehydration (same for Hct and total RBC count)
  43. Hematocrit (Hct)
    • measures packed cell volume of RBCs expressed in percentage of the total blood volume (percentage of RBCs comared to the total volume of blood)
    • female: 35-47%
    • male: 39-50%
    • reduced in anemia, hemorrhage, hemodilution like hypervolemia (same for Hgb)
    • increased in polycythemia, hemoconcentration like dehydration (same for Hgb)
  44. WBC count / diffential
    • total count of WBCs / percentages of each type- valuable in detemining cause of illness
    • normal: 4000-11000/uL
    • total count- increased in infection, inflammation, tissue injury/death, malignancies
    • total count of WBCs of less than 4000/uL- leukopenia - associated with bone marrow depression, sever/chronic illness, and/or type of leukemia
    • "shifts to the left"- many immature cells
    • Neutrophils: 50-70%; Neutropenia - less than 1000 cells/uL - leukemia, bone marrow depression
    • Eosinophils: 0-4%
    • Basophils: 0-2%
    • lymphocytes: 20-40%
    • monocytes: 4-8%
  45. Platelet count
    • number of platelets available to maintain platelet clotting functions
    • normal: 150,000-400,000/uL
    • thrombocytopenia- below 100,000uL- causes bleeding
    • thrombocytosis- disorder of excessive platelets that occurs with inflammation and some malignant disorders; most common complication: excessive clotting
  46. Blood typing
    • type A- has A antigens and has B antibodies
    • type B- has B antigens and has A antibodies
    • type AB (universal recipient)- has both Aand B antigens has neither A or B antibodies
    • type O (universal donor)- has neither A or B antigens has both A and B antibodies
  47. Rh Factor
    • Rh positive have a third antigen, D
    • Rh negative do not

    Important  during pregnancy when Rh negative person may be exposed to Rh positive blood and they end of forming antibodies (anti-D) to attach Rh antigens - subsequent pregnancies these antibodies can attack a fetus who is Rh positive - a Rh Neg woman should receive RhoGAM to prevent these antibodies from forming
  48. lab tests to evaluate iron metabolism
    • serum iron: 50-175mcg/dL- amount of iron combined with proteins, indicates status of iron storage and use
    • total iron binding capacity (TIBC): 250-425 mcg/dL- amount of proteins available for binding iron; indirect measure of transferrin, indicates how much extra iron can be caarried; it is high when iron stores are low and vise versa
    • serum ferritin: 10-250ng/mL- measures the major iron storage protein ferritin, directly related to iron storage; 1ng/mL of ferritin = 8-10mg of stored iron
  49. Image studies / Biopsies for hematology system
    • CT or MRI to evaluate the spleen, liver, and lymph /
    • bone marrow biopsies and lymph node biopsy - provides info for diagnosis and used for planning treatment
    • preferred site for aspiration/biopsy for bone marrow- posterior iliac crest - cleaned with bactericidal agent - causes quick short but very painful (sore for 3-4 days)- afterwards, apply pressure, moitor vitals, assess for potential hemorrhage or infection, pain management
  50. erythrocyte sedimentation rate (ESR)
    • measures settling of RBCs in 1hr; infection or inflammation make them heavier
    • normal: <30mm/hr
  51. activated partial thromboplastin time (aPTT)
    • assesses intrinsic coagulation by measuring factors 1, 2, 5, 8-12
    • normal: 25-35sec (longer with use of heparin)
  52. D-dimer
    • measures a fragment of fribin that results bc of fibrin degradation and clot lysis, used to diagnose hypercoagulable conditions (DIC, PE)
    • normal: <250 ng/mL

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