The Blood

Functions of Blood Transportation O2, nutrients, waste, hormones, heat Regulation—maintain homeostasis of body fluids Regulate pH, body temperature, maintain fluid volume Protection Clotting prevents loss of fluids White blood cells protect against disease Blood proteins protect against disease

Physical characteristics and volume Salty and metallic tasting More dense than water Slightly alkaline, pH between 7.35 and 7.45 Temperature ~ 38o C or 100.4o F Makes up 8% of body weight Volume in adult males is 5-6 L and in females 4-5 L Only fluid tissue in the body

Blood components Blood plasma 55% Formed elements 45% RBCs—measurement is hematocrit 14% + 5% Leukocytes and platelets

Blood plasma Includes over 100 different dissolved solutes

Formed Elements

Hematopoiesis Occurs in the red bone marrow from hemocytoblast/ hematopoietic stem cell Specialization based on receptors that respond to …hormones

Erythrocyte structure Flexible structure, large surface area Lack a nucleus and other organelles. 33% of weight is hemoglobin molecules. Other proteins include antioxidants and those to maintain RBC shape (spectrin)

Erythrocyte function Dedicated to carry respiratory gas

Regulation of RBCs Erythropoietin (EOP) glycoprotein hormone produced by kidneys to liver

Dietary needs to produce RBCs Iron, AAs, lipids, and carbohydrates. Iron is absorbed from the diet 65% found in hemoglobin The rest stored in liver, spleen and bone marrow Iron is toxic and requires transferrin as a transporter Some iron is lost in feces and menstrual blood Vitamin B12 and folic acid are necessary for DNA synthesis

Fate and death of RBCs RBCs have a lifespan of 100 to 120 days Age makes them less flexible and the hemoglobin begins to degenerate. Old RBCs get trapped in the small capillaries of the spleen Macrophages destroy and digest RBCs Heme and globin are separated Globin broken down into a.a.s Heme bilirubinurobilinogenstercobilin Bloodliverintestineanus

Erythrocyte Imbalances Anemia  reduced O2 carrying capacity of the blood Insufficient number of RBCs: Hemorrhagic - due to blood loss associated with an injury, undiagnosed bleeding ulcer, etc. Hemolytic - due to blood loss due to transfusion reactions & certain bacterial and parasite infections Aplastic - due to destruction or inhibition of red marrow by drugs, ionizing radiation or certain bacterial toxins.

Erythrocyte Imbalances Anemia  reduced O2 carrying capacity of the blood Low hemoglobin content: Iron Deficiency - inadequate intake or absorption of iron, forms microcytes. Pernicious - dietary deficiency of Vitamin B12 or inadequate production of intrinsic factor for absorption of Vitamin B12 , forms macrocytes

Erythrocyte Imbalances Anemia  reduced O2 carrying capacity of the blood Abnormal Hemoglobin in RBCs Thalassemias- one globin chain is absent/faulty Polycythemia-excess of erythrocytes increasing blood viscosity

Erythrocyte Imbalances Polycythemia - abnormally high number of RBCs (8 - 11 million/mm3). Increases blood viscosity & blood pressure. most often the result of bone marrow cancer. Lecuopenia - abnormally low number of WBCs (less than 5,000/mm3). drugs, steroids & anti-cancer agents.

Leukocytes Structure WBCs have a nucleus and other organelles. WBCs can undergo diapedesis using amoeboid motion when in the tissues Use chemical chemotaxis to follow trail to infection or damaged tissue.

Granular leukocytes Neutrophils Eosinophils Basophils multilobed nucleus, inconspicuous granules Phagocytize bacteria & some fungi Produced in bone marrow by myeloblasts Eosinophils bilobed nucleus, red granules Destroy parasitic worms & immune complexes Basophils lobed nucleus, purple-black granules Cause vasodilation by release of histamines

Agranular leukocytes Lymphocyte Monocytes B lymphocytes - Humoral Immunity (antibodies) T lymphocytes - Cellular Immunity Produced in lymphatic tissues Monocytes Differentiate into macrophages in tissues. Provide defense against viruses & intracellular bacteria in chronic infections. Produced by monoblasts in lymphatic tissues.

Production of leukocytes Leukopoiesis is stimulated by interleukins and colony-stimulating factors (CSFs) Pluripotent stem cells have the capacity to differentiate into several types of cells. Myeloid stem cells Lymphoid stem cell

Leukocyte Imbalances Leukopenia—low WBC count Leukemia—unchecked growth of a single unspecialized clone. Abnormally high numbers of immature WBCs that are mitotic & unspecialized Acute leukemia occurs if it derives from blast-type cells Chronic leukemia occurs if it derives from later stages Bone marrow is compromised and defense system becomes nonfunctional Infectious mononucleosis derives from excessive numbers of agranulocytes (Epstein-Barr virus)

Platelets Under the influence of thrombopoietin, myeloid stem cells develop into megakaryocytes (huge cells). These cells fragment into 2-3K particles. They have a very short life of 5- 9 days.

Hemostasis Damaged blood vessels require a rapid, localized and controlled hemostatic response to reduce blood loss. Vascular spasm/constriction Platelet plug formation Blood clotting/ coagulation

Platelet plug formation: platelet adhesion

Platelet plug formation: platelet release action

Platelet plug formation: platelet aggregation

Stages of clotting Extrinsic (s) and intrinsic (min) pthwys make prothrombinase. Prothrombinase & Ca2+ Catalyze prothrombin  thrombin Thrombin & Ca2+ converts soluble fibrinogen insoluble fibrin (thread of the clot) Thrombin activates factor XIII which stabilizes & strengthens threads

Hemostasis Animation

Thromboemolitic Disorders Thrombus clot in an unbroken vessel Ebolus an abnormal object moving through a blood vessel, Clot, air bubble, lipid droplet, thrombus, etc. Disorders Embolisms (pulmonary, cerebral, cardiac) Artherosclerosis Inflammation Treatment Aspirin Heparin Warfarin

Bleeding disorders Thrombocytopenia—low platelet levels Impaired liver function Vitamin K Hemophilia Deficiency of factor VIII (antihemophilic factor) Deficiency of factor IX Lack of factor XI

ABO blood typing Based on two glycolipid antigens, A and B. Blood has agglutinogens (antibodies) that react to A or B antigens.

Blood groups and blood types

Rh blood groups Hemolytic disease of newborn (HDN)

Transfusion reactions Agglutination clogs blood capillaries Clumped cells will rupture and be phagocytized by macrophages Hemoglobin is released into the blood Oxygen carrying is disrupted Blood flow is impaired Hemoglobin passing into kidney tubules causes cell death and renal shutdown

Diagnostic blood tests Lipidemia is characteristic of those with heart disease Erythrocyte morphology can detect anemias Differential white blood cell count High eosinophil indicates allergies or parasitic infection Platelet count (thrombocytopenia) SMAC is blood chemistry profile CBC provides information on the formed elements

Resources Heart Anatomy Tutorial: Hematopoiesis Overview: BodySmart Blood & Bloodcells