Blood Erythrocytes (RBC), Leukocytes (WBC), Platelets, & Plasma

Blood Function  Transport nutrients, wastes, body heat, etc thru bv Components  55% Plasma – fluid matrix  45% Erythrocytes (rbc) – O 2 transport  >1% Leukocytes (wbc) – protect body  >1% Platelets – cell fragments used for clotting Fun Facts  4-6 liters of blood per person  7% of body weight  Temp 38 o C  pH between 7.35 – 7.45  Salty-metallic taste  5x thicker than water

Blood Plasma 90% water Distributes body heat through out body Contains dissolved nutrients, salts, resp. gases, hormones, plasma proteins, wastes, and products of cell metabolism Plasma Proteins  Albumin – maintains osmotic pressure of blood  Clotting Proteins – prevents blood loss from injured bv  Antibodies – protect body from pathogens

Erythrocytes (rbc) Biconcave disc shape (large s.a. to volume) Anucleate - lacks a nucleus Lack cellular organelles including mitochondria (so do not use O 2 themselves) Hemoglobin (Hb) – Fe carries 4 molecules O 2  1rbc carries 1 billion molecules O 2  Avg male 13-18g Hb/100ml blood  Avg female 12-16g Hb/100ml blood Anemia – low rbc or low Hb Polycythemia – high rbc (high alt or bone marrow cancer) Last 120 days – broken down by liver and spleen

Leukocytes (wbc) Live days, months, or even years About 4,000-11,000 wbc/mm 3 blood Can move in and out of bv Respond to chems sent out from damaged cells When in action – body doubles #wbc w/in hrs Leukocytosis  >11,000 wbc indicates bacterial or viral infection Leukopenia  Decrease in wbc  Typically due to corticosteroids or anticancer drugs Leukemia  Cancer of bone marrow  Too many immature wbc to defend off pathogens

Types of Leukocytes Granulocytes – granule containing wbc w/lobed nuclei  Neutrophils – phagocytes at site of infection  Eosinophils – increases w/allergies and infections by parasitic worms  Basophils – histamine (chem incr. wbc to site) containing granules Agranulocytes – lack cytolasmic granules  Lymphocytes – in lymphatic tissue (T cells and B cells)  Monocytes – largest wbc Become macrophages when enter tissues Fight off chronic infections

Platelets & Hemostasis Platelets – irregularly shaped, needed for clotting process Hemostasis – local stoppage of blood flow 1. Platelet Plug Forms 1. Platelets become sticky and cling to damaged site 2. Release clotting factors to increase platelets to site to create plug 2. Vascular Spasms Occur 1. Serotonin is released to cause bv to spasm and narrow to decrease blood loss 3. Coagulation 1. Injured tissue releases “Tissue Factor” (TF) 2. TF combines with Ca +2, vitamin K, and PF3  prothrombin 3. Prothrombin converted to thrombin 4. Thrombin + fibrinogen  Fibrin 5. Fibrin traps rbc to start clot and pulls ruptured bv closer together

Hematopoiesis – Blood Cell Formation Hemocytoblast  stem cell in rbm takes 3-5 days to form rbc  Rbc divides and synthesizes Hb  Incr. Hb ejects nucleus and most organelles  Enters bloodstream Rbc falls apart in days  Eliminated by phagocytes, spleen, and liver Erythropoietin  hormone controls rate of rbc production  Produced by kidneys and targets bone marrow Thrombopoietin – increases production of platelets Interleukins and colony stimulating factors  increase production of wbc from bone marrow  Released in response to inflam chems, bacteria, or toxins

Blood Types & Transfusions Phlebotomist – hs degree + training + exam ABO Blood Groups  Based on 2 antigens A&B  Antibodies formed in infancy  Determined by anti-A, and anti- B serums Rh Blood Groups  Once Rh- contacts Rh+ produces antibodies  Pregnant Rh- mom carrying Rh+ baby  RhoGAM prevents moms antibodies from attacking fetus Hemolysis – rupture of rbc

Fetal Hb vs. Adult Hb By day 28 of fetal development – embryonic blood cells circulate in blood vessels Fetal Hb (HbF) differs from adult HbA HbF has a greater ability to pick up O2 b/c fetal blood less O2 rich than mothers If fetal rbc destroyed so quick that liver cannot rid of bile fast enough  causes infant jaundice