Hematologic System

Mehtap KAÇAR KOÇAK M.D. PhDPathophysiologist

Yeditepe University, Faculty of Medicine

Hematologic System

• The blood and the blood forming sites, including the bone marrow and the reticuloendothelial system

• Blood

– Plasma

– Blood cells

• Reticuloendothelial System

• Hematopoiesis

Functions of Blood• Blood is a type of connective tissue that

continuously circulates through the heart and blood vessels performing 3 major FUNCTIONS:– Transportation of oxygen, nutrients,

hormones & waste products– Regulation of fluid, electrolyte & acid-base

balance• Controls body temperature, controls water

content of cells

– Protection: clotting & combating infection

Components of blood• Plasma

– 55% of blood is plasma– Composed of water, protein,

electrolytes, gases, nutrients and waste

– Plasma proteins include:• Albumin – pulls tissue fluid

into capillaries to maintain blood volume & BP

• Globulin – antibodies to help fight infection

• Fibrinogen – blood clotting factor

• Hematocrit measures the packed cell volume of RBCs.

• Hemoglobin 14-18 g/dl (M) & 12-16 g/dl (W)

Blood Cells • Erythrocyte: RBC• Leukocyte: WBC

– Neutrophil– Monocyte– Eosinophil – Basophil – Lymphocyte: T lymphocyte and B lymphocyte

• Thrombocyte: platelet

RBC’S: Erythrocytes

• RBCs are flexible, biconcave discs that can alter shape to fit through tiny capillaries.

• The primary functions of RBCs are:Transportation of O2 & CO2

Maintain acid-base balance by transporting carbon dioxide (as acid) for disposal by lungs

RBC’S Functions:• RBCs contain Hemoglobin

(Hgb):– Iron (heme)- binds easily with

oxygen– Protein (globin) compound

binds with carbon dioxide• When the RBCs flow through

body tissues, oxygen detaches from the Heme & diffuses from the capillary into the body cells.

• Carbon dioxide diffuses from the body cells into the capillaries & binds to the globin portion of the Hgb.

• In the lungs, the carbon dioxide is released for removal from the body & oxygen taken up.

Erythropoiesis:• Production of RBC’S• Reticulocytes- Immature erythrocyte• Erythropoietin- hormone produced mainly by

kidneys (stimulates marrow to increase production of RBC’S)

• Normal erythrocyte production requires; iron, vit.B12, folic acid, vit.B6, pyroxidine, and protein Average diet in US contains 10 to 15mg iron

• Only 0.5 to 1mg eaten is absorbed from small intestine

Erythropoiesis:• Women of childbearing age need up to 2mg

more/day

• Total body content 3g. Most in hemoglobin

• Iron deficiency in adult indicates blood loss

(lack of dietary iron rarely the sole cause)

• Average RBC lifespan: 120 days

• Aged RBC’s removed from blood in liver & spleen

• Hemoglobin recycled or broken down to form bilirubin then secreted in bile

• Most of the iron is recycled to form new hemoglobin

Leukocytes: WBC• There are 5 different types

of WBC:– Granulocytes - contain

granules• Neutrophils, basophils,

eosinophils– Agranulocytes – do not

contain granules• Lymphocytes (principal cells of immune

system)• Monocytes (transform into

Macrophages)• Larger than RBCs.

WBC’S: Functions• Functions:

– Neutrophils and monocytes phagocytize pathogens & dead tissue

– Eosinophils detoxify foreign proteins, especially during allergic reactions and parasitic infections

– Basophils contain the anticoagulant heparin to help prevent abnormal clotting and histamine which contributes to inflammation

– Lymphocytes: T cells help recognize foreign antigens and stop the immune response when the antigen has been destroyed. B cells become plasma cells that produce antibodies

WBC’S: Functions• The lifespan of white blood cells ranges from

13 to 20 days, after which time they are destroyed in the lymphatic system.

• Leukocytes fight infection through a process known as phagocytosis. During phagocytosis, the leukocytes surround and destroy foreign organisms.

• White blood cells also produce, transport, and distribute antibodies as part of the body's immune response.

Thrombocyte: platelet

• Platelets are formed in red bone marrow from stem cells that change into megakaryocytes

• Blood clotting process (hemostasis) minimizes blood loss when injured.

• Normal clotting has 3 components:– Vascular Response– Platelet Response– Coagulation Response

Blood Smear

Hemostasis

HemostasisVascular Response:

– Local vasoconstriction reduces blood loss & presses endothelial surfaces together

– Vascular spasm may last 20-30 minutes to allow time for the platelet response to occur

HemostasisPlatelet Response:

Platelets activated when exposed to collagen from injured blood vessel.

Platelets release platelet factor 3 & serotonin

Platelets stick to each other to form clumps, agglutination, that form a platelet plug

Hemostasis

Coagulation Response

• Clot is formed of fibrin threads that form a mesh over the break in the vessel

Hematopoiesis

Hematopoiesis• Blood cell formation

• Occurs in bone marrow from stem cells

(liver and spleen can also produce blood cells)

extramedullary hematopoiesis

Sites:

children: all skeletal bones

adults: pelvis, ribs, vertebrae, and sternum

LabsThe CBC is most

common testAlong with peripheral

blood smear

It involves several tests, each of which assesses the three major cells formed in the bone marrow.– Red & white cell

counts – Hematocrit &

hemoglobin levels

– Erythrocyte indices

– Differential white cell count

– Examination of the peripheral blood cells.

Hgb&Hct• Hemoglobin is the

main component of RBCs & carries the oxygen & CO2

• Important in determination of anemia

• Hematocrit represents RBC mass & is used to identify anemias

• Measured in %

Red Cell Indices

• Red cell indices are measurements of the size & hemoglobin content of erythrocytes

• Low Hemoglobin (Hgb) indicates decreased ability to carry O2 to the cells as well as the condition of anemia.

• Increased WBC count indicates infection or inflammation.

• Increased RBC indicates that the body is compensating for chronic hypoxemia (abnormal deficiency of O2 in the arterial blood) by stimulating RBC production by the bone marrow, leading to secondary polycythemia

Labs: Sedimentation Rate

• The rate at which RBCs settle out of anticoagulated blood in 1 hour.

• Indicates that a disease process is occurring (inflammation)

• Its serial estimation of values gives the idea of the progress of the disease.

• Erythrocyte Sedimentation Rate (ESR) is used to monitor/rule out inflammatory conditions of the heart (increased with MI & bacterial endocarditis).

Labs: Sedimentation Rate

• E.S.R. is increased in acute & chronic inflammatory disease & in cancerous conditions. The ESR may be very high (>100 mm/hour) in multiple myeloma, tuberculosis & temporal arthritis. A low ESR (<1 mm/hour) may be seen in congestive heart failure & sickle cell disease.

• After a heart attack, the E.S.R becomes raised & may remain so for several days.

Labs: CBC: WBC• Function in immune defense• Value: 4500 – 11,000/uL

– Shift to the Left = increased number of immature WBCs (Reticulocytes) in peripheral blood

– Low + shift left = recovery from bone marrow depression or massive infection

– High + left shift = response to overwhelming infection

– Shift to the Right = cells have more nuclear segments; liver disease, Down’s; pernicious anemia

DifferentialWBC

• The percentage of each of the five types of white blood cells in a sample of blood.

• Reported in percentages & always add up to 100%. • Normal values for total WBC & differential in adult males & females

are: – Total WBC: 4,500 - 10,000 – Bands or stabs: 3 - 5 % – Granulocytes– Neutrophils (or segs): 50 - 70% relative value (2500-7000

absolute value) – Eosinophils: 1 - 3% relative value (100-300 absolute value) – Basophiles: 0.4% - 1% relative value (40-100 absolute value) – Lymphocytes: 25 - 35% relative value (1700-3500 absolute value) – Monocytes: 4 - 6% relative value (200-600 absolute value)

Labs: CBC: Platelets

• Platelets function in hemostasis

• Value: 150,000 – 400,000 cells/uL

– Monitor site for bleeding in clients with known thrombocytopenia

– Bleeding precautions should be implemented on clients with a low platelet count

Labs: Coagulation studies

• Used for monitoring patients receiving anticoagulant drug therapy.

• Important for patients with chronic atrial fibrillation.

• a patient with atrial fibrillation who is to undergo cardioversion.

• Studies include Prothrombin time (PT) & activated partial thromboplastin time (aPTT). Usually an INR (International Normalized Ratio) is done with a PT.

Prothrombin Time (PT) & INR• This test gives an indication of blood clotting time,

although the clotting factors measured are different from those in the thrombin test.

• Used to monitor response to warfarin sodium (Coumadin) therapy or DIC.

• A PT value within 2 seconds of the control is normal.

• The INR standardizes the PT ratio by comparing the ct’s PT time with a control value;

• Average PT: 9.6-11.8 (male) & 9.5-11.3 (female)– Will be prolonged with Coumadin therapy

• INR: 2-3 for Coumadin therapy• INR: 3-4.5 for high-dose Coumadin therapy

PT & INR

• Baseline PT should be drawn before starting anticoagulation therapy is started

• A PT > 30 sec places client at risk for hemorrhage

Activated Partial Thromboplastin Time (PTT)

• Evaluates how well the coagulation sequence is functioning. Measures how long it takes for blood to clot after thromboplastin is added.

• Screens for deficiencies of factors.• Used to monitor heparin therapy & screen for

coagulation disorders.• When a client is receiving heparin, aPTT

should be between 1.5 – 2.5 times normal. If longer, then initiate bleeding precautions.

Anticoagulants• Thrombosis is prevented in vessels by:

– The very smooth epithelial lining of blood vessels– Heparin (from basophils) which blocks chemical

clotting– Antithrombin (from the liver) which inactivates

excess thrombin

• Fibrinolysis is the dissolving of a clot that has served its purpose – Plasmin splits fibrin or fibrinogen– Excessive fibrinolysis bleeding tendencies r/t

destroyed platelet plugs

Blood Cultures

• A blood culture identifies the bacteria causing the disease so, that an appropriate medication can be

prescribed.

Blood Culture Bottle & Plate

Labs: Arterial Blood Gases• Used in patients with

unstable cardiac conditions to determine adequacy of blood oxygenation process.

• The blood sample is taken from an artery & not from the vein.

• The arterial paO2 measures the oxygenation of the blood

• The arterial paCO2 measures the bodies ability to excrete the carbon dioxide.

Bone Marrow Biopsy

• Bone marrow examination is important to many hematologic disorders. Provides data about full hematopoiesis.– Preferred site is iliac crest– Performed by physician or APN– Conscious sedation to minimize pain & anxiety– Local anesthetic use– Pt experiences pain with aspiration– Put pressure on site after to ensure hemostasis.

Bone Marrow• Aspiration only

– iliac crest or sternum– Skin cleansed– Local infiltrated

• Styled inserted– Syringe attached– 0.2-0.5 cc fluid is

aspirated– Slide Prepared– Pressure applied

post procedure– Risks:

• Hemorrhage• Infection

Bone Marrow Biopsy

• Aspiration with Biopsy– Same prep– Uses a needle with a

cutting blade– Specimen removed

• Small for biopsy• Larger for

graft/donor– Slide prepared– Pressure dressing– Risks:

• Hemorrhage• Infection