Chapter 19 Cardiovascular System Blood: Functions. Plasma

Transcription

1 Chapter 19 Cardiovascular System Blood: Functions 19-1 Plasma Liquid part of blood. Colloid: liquid containing suspended substances that don t settle out of solution 91% water. Remainder proteins, ions, nutrients, waste products, gases, regulatory substances Proteins: Albumins: viscosity, osmotic pressure, buffer, transports fatty acids, free bilirubin, thyroid hormones Globulins: Transports lipids, carbohydrates, hormones, ions, antibodies, and complement Fibrinogen: blood clotting

2 Plasma, cont. Ions: involved in osmosis, membrane potentials, and acid-base balance Nutrients: glucose, amino acids, triacylglycerol, cholesterol, vitamins Waste Products: Urea, uric acid, creatinine, ammonia salts. Breakdown products of protein metabolism Bilirubin. Breakdown product of RBCs Lactic acid. End product of anaerobic respiration Gases: oxygen, carbon dioxide, and inert nitrogen Regulatory substances: hormones, enzymes 19-3 Composition of Blood

3 Formed Elements Red blood cells (erythrocytes). Biconcave discs, anucleate, contain hemoglobin; transports oxygen and carbon dioxide. White blood cells (leukocytes) Granulocytes: cytoplasm contains large granules; have multi-lobed nuclei. Three distinctive types: neutrophils, eosinophils, basophils Agranulocytes: cytoplasm contains small granules and nuclei that are not lobed. Two distinctive types: lymphocytes and monocytes Platelets (thrombocytes). Cell fragment. Form platelet plugs, release chemicals necessary for blood clotting

4 Hematopoiesis 19-7 Red Blood Cells Found in higher concentration in male than in female plasma Components 1/3 Hemoglobin 2/3 Lipids, ATP, carbonic anhydrase

5 Hemoglobin Types of hemoglobin Embryonic and fetal: have greater attraction for oxygen than adult. Fetal production stops after birth. Adult Oxyhemoglobin: transporting oxygen Dexoyhemoglobin Carbaminohemoglobin: transporting carbon dioxide 19-9 Erythropoiesis RBCs last 120 days in circulation (enucleated) Production of red blood cells (Stem cells proerythroblasts early erythroblasts intermediate erythroblasts late erythroblasts reticulocytes) Erythropoietin: hormone stimulates RBC production; produced by kidneys in response to low blood O 2 levels

6 Hemoglobin Breakdown Neutrophils: after leaving bone marrow, stay in circulation hours then move into other tissues. Become motile, phagocytize bacteria, antigen-antibody complexes and other foreign matter. Secrete lysozyme. Last 1-2 days. Eosinophils. Leave circulation and enter tissues during inflammatory response. Prevalent in allergic reactions. Destroy inflammatory chemicals like histamine. Release chemicals that help destroy Parasites (tapeworms, flukes, pinworms, and hookworms.)

7 Basophils: least common. Leave circulation and migrate through tissues, play a role in both inflammatory response and allergic reactions. Produce histamine and heparin. Lymphocytes: produced in red bone marrow but then migrate to lymphatic tissues and proliferate. Responsible for antibody production. Studied extensively with the immune system. Monocytes: remain in circulation for 3 days, leave circulation and become macrophages. Phagocytic cells. Can break down antigens and present them to lymphocytes for recognition Platelets Cell fragments pinched off from megakaryocytes in red bone marrow Surface glycoproteins and proteins allow adhesion to other molecules; i.e., collagen Important in preventing blood loss Platelet plugs Promoting formation and contraction of clots

8 Hemostasis Arrest of bleeding Events preventing excessive blood loss Vascular spasm: Vasoconstriction of damaged blood vessels. Can occlude small vessels. Caused by thromboxanes from platelets and endothelin from damaged endothelial cells. Platelet plug formation Coagulation or blood clotting Platelet Plug Formation 1. Platelet adhesion. Occurs when von Willebrand factor connects collagen and platelets. 2. Platelet release reaction. The release of ADP, thromboxanes, and other chemicals that activate other platelets. They in turn undergo the release reaction: cascade effect. 3. Platelet aggregation. Activated platelets express surface receptors that bind fibrinogen (protein found in plasma). Fibrinogen forms a bridge between platelets: platelet plug. 4. Expression of coagulation factor V and phospholipids. Important for coagulation

9 Coagulation Stages 1.Activation of prothrombinase 2.Conversion of prothrombin to thrombin 3.Conversion of fibrinogen to fibrin (See Handout) Coagulation factors. Proteins found in plasma. Circulate in inactive state until tissues are injured. Damaged tissues and platelets produce chemicals that begin activation of the factors. Pathways Extrinsic Intrinsic Result: blood clot. A network of threadlike fibrin fibers, trapped blood cells, platelets and fluid Clot Formation

10 Control of Clot Formation Anticoagulants: prevent coagulation factors from initiating clot formation.. Anticoagulants Antithrombin: produced by liver, slowly inactivates thrombin Heparin: produced by basophils and endothelial cells. Increases effectiveness of antithrombin Prostacyclin: prostaglandin derivate from endothelial cells. Causes vasodilation and inhibits release of coagulating factors from platelets Fibrinolysis Clot retraction. Fibrin threads of clot attached to blood vessel walls. Platelets produce processes that attach to fibrin threads. Actin and myosin molecules within platelets contract, pulling edges of wound together and squeezing out serum. Clot dissolved by activity of plasmin, an enzyme which hydrolyzes fibrin

11 Blood Grouping (Transfusion: transfer of blood or blood components from one individual to another) Determined by antigens (agglutinogens) on surface of RBCs Antibodies (agglutinins) can bind to RBC antigens, resulting in agglutination (clumping) or hemolysis (rupture) of RBCs Groups: ABO and Rh ABO Blood Groups

12 Transfusion Type A blood has anti-b antibodies; Type B blood has anti-a antibodies (Suggested that these antibodies are present because of exposure to A and B antigens on bacteria and food) Donor: gives blood. Recipient: receives blood Type O as universal donor. (Can actually cause transfusion reactions because of antibodies in O blood plasma) Rh Blood Group First studied in rhesus monkeys Types Rh positive: Have these antigens present on surface of RBCs Rh negative: Do not have these antigens present Hemolytic disease of the newborn (HDN) Rh positive fetus, Rh negative mother. Late in pregnancy, Rh antigens of fetus cross placenta (through a tear in placenta or during delivery); mother creates antirh antibodies (primary response) Second Rh positive pregnancy might initiate secondary response and HDN (potentially fatal to fetus since antibodies to its RBCs would cross the placenta from the mother to the fetus, destroying fetal RBCs). Injection of RhoGAM. Contains antibodies against Rh antigens. Antibodies attach to any fetal RBCs and they are destroyed

13 Erythroblastosis Fetalis Diagnostic Blood Tests Type and Crossmatch: determination of ABO and Rh blood types. Red cells tested against antibodies Complete Blood Count Red Blood Count: number of RBCs/ microliter of blood Hemoglobin Measurement: grams of hemoglobin/100 ml of blood. For a male, 14-18, female g/100 ml Hematocrit Measurement: percent of blood that is RBCs White Blood Cell Count: 5,000-10,000 /microliter of blood

14 Differential White Blood Count: determines percentage of each of the five types of WBC Neutrophils: 60-70% Lymphocytes: 20-30% Monocytes: 2-8% Eosinophils: 1-4% Basophils: 0.5-1% Clotting Platelet Count: 250, ,000/microliter Prothrombin Time Measurement: measures how long it takes for blood to start clotting seconds. To test, thromboplastin is added to whole plasma Blood Chemistry: composition of materials dissolved or suspended in the plasma. Used to assess functioning of many body systems