The Blood Functions of Blood Transportation O 2

The Blood

Functions of Blood • Transportation – O 2, nutrients, waste, hormones, heat • Regulation—maintain homeostasis of body fluids – Regulate p. H, 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, p. H between 7. 35 and 7. 45 • Temperature ~ 38 o C or 100. 4 o 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 B 12 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 O 2 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 O 2 carrying capacity of the blood • Low hemoglobin content: • Iron Deficiency - inadequate intake or absorption of iron, forms microcytes. • Pernicious - dietary deficiency of Vitamin B 12 or inadequate production of intrinsic factor for absorption of Vitamin B 12 , forms macrocytes

Erythrocyte Imbalances • Anemia reduced O 2 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/mm 3). Increases blood viscosity & blood pressure. • most often the result of bone marrow cancer. • Lecuopenia - abnormally low number of WBCs (less than 5, 000/mm 3). • 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 • multilobed nucleus, inconspicuous granules • Phagocytize bacteria & some fungi • Produced in bone marrow by myeloblasts • Eosinophils • bilobed nucleus, red granules • Destroy parasitic worms & immune complexes • Produced in bone marrow by myeloblasts • Basophils • lobed nucleus, purple-black granules • Cause vasodilation by release of histamines • Produced in bone marrow by myeloblasts

Agranular leukocytes • Lymphocyte – 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 -3 K 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 & Ca 2+ Catalyze prothrombin • Thrombin & Ca 2+ 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: • Body. Smart Blood & Bloodcells