Blood chapter 17 LO

Hematopoiesis

(hemopoiesis) - blood cell formation -- occurs in red bone marrow of axial skeleton, girdles and proximal epiphyses of humerus and femur - hemocytoblasts (hematopoietic stem cells) -- gives rise to all formed elements: RBC, WBC, & Platelets -- hormones and growth factors push the cell toward a specific pathway of blood cell development - new blood cells enter blood sinusoids

thromboembolytic conditions

*thrombus*: clot that develops and persists in an unbroken blood vessel -- may block circulation, leading to tissue death *Embolus*: a thrombus freely floating in the blood stream -- pulmonary emboli impair the ability of the body to obtain oxygen -- cerebral emboli can cause strokes

Erythrocyte disorders

- Polycythemia: excess of RBCs that increase blood viscosity -- results from: ===== bone marrow cancer ===== less o2 is available (high altitude) or when EPO production increases ===== blood doping

thromboembolytic conditions preventions

- aspirin - heparin -- anticoagulant used clinically for pre and postoperative cardiac care -warfarin -- used for those prone to atrial fibrillation

hormonal control of Erythropoiesis

- effects of EPO -- more rapid maturation of cells -- increased reticulocyte count in 1-2 days - testosterone also enhances EPO production, resulting in higher RBC counts in males

monocytes

- large leukocytes - pale cytoplasm - dark- purple staining, U or kidney shaped nuclei - *differentiate into macrophages* -- *phagocytic* - *activate lymphocytes to mount an immune response*

Neutrophils

- most numerous WBCs - polymorphonuclear leukocytes (PMNs) - fine granules take up both acidic and basic dyes - pale lilac color - granules contain defensins - *very phagocytic* = "bacteria slayers"

inhibition of clotting factors

- most thrombin is bound to fibrin threads and prevented from acting elsewhere -antithrombin III, protein C, and heparin inactivate unbound thrombin and other procoagulants - platelet adhesion is prevented by: + smooth endothelial lining of blood vessels + other anticoagulants like nitric oxide and vitamin E.

Clot retraction

- platelets contract - platelet-derived growth factor (PDGF): stimulates division of smooth muscle cells and fibroblasts to rebuild blood vessel wall - vascular endothelial growth factor (VEGF): stimulates endothelial cells to multiply and restore the endothelial lining

Leukopoiesis

- production of WBCs - Stimulated by chemical messengers from bone marrow and mature WBCs -- interleukins -- colony-stimulating factors (CSFs) named for the WBC type the stimulate (e.g., granulocyte-CSF stimulates granulocytes) -All leukocytes originate from hemocytoblasts

basophils

- rarest WBCs - large purplish- black (basophilic) granules contain histamine -- *histamine: inflammation; vasodilator and attracts other WBCs to inflamed sites* -- *heparin: anticoagulant* - are functionally similar to mast cells

eosinophils

- red staining, bilobed nuclei - red to crimson (acidophilic) granules - *digest parasitic worms that are too large to phagocytize* - *allergy and asthma and immune responses*

disorders of hemostasis

- thromboembolytic disorders: undesirable clot formation - bleeding disorders: abnormalities that prevent normal clot formation

regulation of erythropoiesis

- too few RBCs leads to tissue hypoxia (= results from a failure at any stage in delivery of oxygen to cells) - too many RBCs increases blood viscosity (thicker blood) - balance between RBC production and destruction depends on: -- hormonal controls- *erythropoietin (EPO)* from kidneys causes RBC production -- adequate supplies of iron, amino acids and B Vitamins

hemoglobin (Hb)

- when o2 loading in the lungs = produces oxyhemoglobin - when o2 unloads in the tissues = produces deoxyhemoglobin or reduced hemoglobin (dark red or what the "blue" looks like - CO2 loading in the tissue = produces carbaminohemoglobin (carries 20% of CO2 in the blood)

Causes of anemia: 1. Insufficent erythrocytes

-Hemorrhagic anemia: acute or chronic loss of blood -Hemolytic anemia: RBCs rupture prematurely -Aplastic anemia: destruction or inhibition of red bone marrow

leukocyte disorders

-Leukopenia -- abnormally low WBC count - drug induced - Leukemias -- cancerous conditions involving WBCs -- named according to the abnormal WBC clone involved that impairs normal red bone marrow function -- *Myelocytic leukemia*: involves myeloblasts -- *lymphocytic leukemia*: involves lymphocytes -- *acute leukemia*: involves blast-type cells and primarily affects children -- *chronic leukemia*: is more prevalent in older people

2. platelet plug formation

-Positive feedback cycle (keep building the plug) -- platelets stick to exposed collagen fibers -- released chemical messengers causing more platelets to stick

factors limiting clot growth or formation

-Two homeostatic mechanisms prevent clots from becoming large -- removal of clotting factors -- inhibition of clotting factors *in order to clot, the concentration of clotting factors must hit a threshold level which occurs when vessel and tissue is damaged*

1. Vascular spasm

-Vasoconstriction triggered by: -- direct injury -- chemicals released by endothelial cells and platelets -- pain reflexes

hemoglobin

-a protein that makes RBC red -binds easily and reversibly with oxygen -and most oxygen carried in blood is bound to hemoglobin

lymphocytes

-large, dark-purple, circular nuclei with a thin rim of blue cytoplasm -mostly in lymphoid tissue -crucial to *immunity* small compared to RBC

Platelets

-small fragments of megakaryocytes - bluish/purple stained - granules contain serotonin, Ca2+, enzymes, ADP and platelet-derived growth factor - forms a temporary platelet plug that helps seal breaks in blood vessels

Transfusions

-whole blood transfusions are used when blood loss is substantial -packed red cells (plasma removed) are used to restore oxygen carrying capacity - transfusions incompatible blood can be fatal

3 steps of hemostasis

1. Vascular spasm 2. Platelet plug formation 3. Coagulation

agranulocyte

2 types: lymphocytes & monocytes -- lack cytoplasm granules -- have spherical or kidney shaped nuclei

granulocytes

3 types: neutrophils, eosinophils, basophils -- cytoplasmic granules stain certain colors with specific stain -- larger and shorter lived then RBCs -- Lobed nuclei -- Phagocytic

describe the overall composition of plasma

90% water proteins -- albumin -- globulins -- fibrinogen waste nutrients electrolytes gases hormones

Formed elements

Erythrocytes= RBC Leukocytes= WBC Platelets -Only WBC are complete cells -RBCs have no nuclei or organelles -platelets are cell fragments -most blood cells originate in red bone marrow and do not divide

3. coagulation

Fibrin mesh forms a glue 3 phases of coagulation: 1. prothrombin activator is formed 2. prothrombin > thrombin 3. thrombin catalyzes binding of fibrinogen molecules together to form fibrin mesh

Causes of anemia: 2. Low hemoglobin content

Iron deficiency anemia: -secondary result of hemorrhagic anemia or - not enough iron intake - or impaired iron absorption Pernicious anemia: - deficiency of Vitamin B12 - lack of intrinsic factor (hormone) needed for absorption of B12

5 types of leukocytes

Neutrophils- granulocytes eosinophils- granulocytes basophils- granulocytes Lymphocytes- agranulocyte Monocytes- agranulocyte

Erythrocytes

Red blood cells: filled with hemoglobin (Hb) for gas transport Blood viscosity Gas transport: -- shape -- 97% hemoglobin (not counting water) -- no mitochondria, ATP production is anaerobic, no O2 is used in generation of ATP

Causes of anemia: 3. Abnormal hemoglobin

Thalassemias: (sea blood) - absent or faulty globin chain (protein chain) - RBCs are thin, delicate, and deficient in hemoglobin (not properly formed) Sickle-cell anemia: - defective gene codes for abnormal hemoglobin (HbS) - (stiffer harder cells...harder to move through vessels) - causes RBCs to become sickle shaped in low oxygen situations

Bleeding disorders

Thrombocytopenia Impaired liver function hemophilias

Leukocytes

White Blood cells - make up <1% of total blood volume - move through tissue spaces -- positive chemotaxis - Leukocytosis: WBC count over 11,000/mm3 -- normal response to bacterial or viral invasion

describe the major types of plasma proteins, their functions and where they are produced in the body

albumin - produced by the liver: 60% of plasma proteins -- osmotic pressure, buffer and transporter Globulins - produced by the liver: 36% of plasma proteins -- transport proteins: alpha and beta -- antibodies: gamma Fibrinogrn - produced by the liver: 4% of plasma proteins - clotting

coagulation

blood clotting

Leukemia

bone marrow full with cancerous leukocytes death caused by internal hemorrhage and infections treatments include irradiation, antileukemic drugs and stem cell transplants

hemoglobin molecules

contain 1 iron atom each iron atom carries 4 molecules of oxygen

Thrombocytopenia

deficient number of circulating platelets -- spots on skin appear due to wide spread hemorrhage -- from suppression or destruction of bone marrow (malignancy or radiation) -- platelet count <50,000/mm3 is diagnostic -- treated with transfusions of concentrated platelets

state the normal ranges for erythrocytes counts

erythrocytes = 4- 6 million / ul (mm3 = microliter)

hemostasis

fast series of reactions for stoppage of bleeding

impaired liver function

inability to synthesize procoagulants causes include vitamin K deficiency, hepatitis and cirrhosis

hemophilias

include several similar hereditary bleeding disorders (missing on factor of cascade) -- hemophilia A: most common type -- also Hemophilia B and C -- prolonged bleeding especially into joint cavities Treated with plasma transfusions and injection of missing factors

plasma proteins

make up 8% (by weight) of plasma all contribute to osmotic pressure (keeps water in blood) maintain water balance in blood and tissue all have functions as: -- transport -- enzymatic -- buffer

Fibrinolysis

removing unneeded clots when healing has occurred - begins within two days plasmin --> fibrin-digesting enzyme

disseminated intravascular coagulation (DIC)

widespread clotting blocks intact blood vessels - severe bleeding occurs because residual blood unable to clot - most common in pregnancy complications, septicemia, or incompatible blood transfusions