BSC 2086 1st Edition Lecture 8 Outline of Last Lecture I. Components and Functions of BloodII. Physical Characteristics of Blood III. PlasmaIV. Blood Typing Outline of Current Lecture I. Blood Typing Continued II. White Blood Cells III. PlateletsIV. Hemostasis Current LectureI. Blood Typing Continued a. Rh Factor i. D antigenii. Two options: Rh positive (Rh+) or Rh negative (Rh-)iii. Anti-Rh antibodies only found in sensitized Rh- blood b. Transfusionsi. Cross reactions aka. Transfusion reaction 1. Plasma antibody meets its specific antigen2. Blood agglutinates and hemolyzes3. This happens when the donor and recipients blood types are NOT compatibleii. Testing for compatibility1. Performed on donor and recipient2. Type O- is universal donor if a cross match is not made a. Cross match: exposing donors RBCs to recipients plasma II. White Blood Cellsa. Structurei. Aka. leukocytesii. No hemoglobiniii. Have nuclei and other organellesb. Functionsi. Part of immune system, therefore defend against pathogensii. Remove wastes and toxinsiii. Attack foreign or abnormal cells c. Circulation and Movementi. Found in connective tissue as well as in lymphatic system organsii. Small amount found in blood iii. Can migrate out of bloodstream1. Some types of capillaries have gaps to allow cells to leaveiv. Amoeboid movement1. Allows them to squeeze into little gaps in capillaries v. Drawn to chemical stimuli1. Positive chemotaxis2. Positive: presence of these chemicals will attract WBCs into the area vi. Some are phahocytic (neutrophils, eosinophils, monocytes)d. Typesi. Neutrophils (granulocytes)1. Aka. polymorphonuclear leukocytes2. Pale cytoplasm granules with lysosomal enzymes and bactericides 3. 50-70% of WBCs that are circulating4. Action:a. First attackers of bacteria very active b. Phagocytic: engulf and digest pathogensc. Degranulation involves removal of granules from cytoplasm lysosome fuses to endosome i. Peptides from lysosomes known as defensins attackthe membranes of the pathogensd. Release prostaglandins and leukotrienes i. Increases inflammation and attracts other phagocytes e. Form pus i. Made of dead neutrophils, cellular debris and wastes ii. Eosinophils (Acidophils) granulocytes 1. 2-4% of WBCs that are circulating 2. Attack large parasites and excrete toxins (nitric oxide and cytotoxicenzymes)3. Sensitive to allergensa. Increases during allergic reactions 4. Use enzymes that oppose the inflammatory effects of neutrophils and mast cells in order to control or reduce inflammationiii. Basophils (granulocytes)1. Less than 1% of circulating WBCs2. Accumulate in damaged tissue3. Release histamine to dilate blood vessels and heparin to prevent blood clotting iv. Monocytes (agranulocytes)1. 2-8% of circulating WBCs2. Very large and spherical3. Become macrophages when entering peripheral tissues4. Phagocytic 5. Secrete special substance that attracts immune system cells and fibrocytes to the area injured v. Lymphocytes (agranulocytes) 1. 20-30% of circulating WBCs2. Larger than RBCs, therefore able to migrate in and out of blood 3. Found in connective tissues and lymphoid organs 4. Part of bodies defense system 5. Three classes:a. T cellsi. Cell-mediated immunityii. Directly attack foreign cellsb. B cellsi. Humoral immunityii. Become plasma cells and synthesize antibodies c. Natural killer (NK) cellsi. Detects and destroy abnormal tissue cells1. Cancer e. Differential Counti. Detects changes in WBC amounts due to infections, inflammation and allergic reactionsf. Disorders i. Leukopenia: abnormally low countii. Leukocytosis: abnormally high countiii. Leukemia: extremely high count g. Productioni. All blood cells come from hemocytoblasts 1. Produce progenitor cells (myeloid stem cells and lymphoid stem cells)2. Myeloid stem cells: produce all types except lymphocytes3. Lymphoid stem cells: make lymphocytes through lymphopoiesis ii. All except monocytes develop in bone marrowiii. Monocytes develop into macrophages in peripheral tissues1. Start developing in red bone marrow but enter bloodstream before completionIII. Platelets a. Structure i. Cell fragmentsii. Involved in clottingiii. Thrombocytes: type found in nonmammalian vertebrates (nucleated cells)iv. Circulate for 9-12 days and removed by spleen v. 2/3 are kept on reserve for emergenciesb. Countsi. Thrombocytopenia: abnormally low count ii. Thrombocytosis abnormally high countc. Functionsi. Release important chemicals necessary for clottingii. Patch damaged blood vessel walls temporarilyiii. Reduce the size of a break in a blood vesseld. Production i. Thrombocytopoiesis: in bone marrow 1. Megakaryocytes: giant cells that manufacture platelets from cytoplasm a. Develop from myeloid stem cellsIV. Hemostasis a. Definition: cessation of bleeding b. Three phases:i. Vascular Phase 1. A 30 minute vascular spasm occurs after a cut 2. Three steps:a. Endothelial cells contract and uncover basement membrane to the bloodstreamb. Endothelial cells will release ADP, tissue factor and prostacyclin (chemicals)i. Release endothelins (local hormones)ii. Stimulate smooth muscle contraction and cell division 1. Smooth muscle contraction will squeeze and cause blood vessel to constrict so you don’t lose a lot of blood 2. Cell division to make up for a part that’s damaged c. Plasma membranes of endothelial cells becomes sticky andseal off blood flowii. Platelet Phase 1. Starts 15 seconds after injury2. Platelet adhesion or attachment to:a. Sticky endothelial surfacesb. Basement membranesc. Exposed collagen fibers 3. Platelet aggregation or stick together a. Platelet plug forms when platelets are activated and stick to other plateletsb. Closes small breaksc. When platelets are activated they form:i. Adenosine triphosphate (ADP) – excites platelet secretion and aggregationii. Thromboxane A2 and serotonin both cause vascularspasmsiii. Clotting factorsiv. Platelet derived growth factor (PDGF) – promotes repair of vessels v. Calcium ionsd. Platelet plug growth is limited byi. Prostacyclin: inhibits platelet aggregationii. Inhibitors made by other WBCsiii. Circulatory enzymes that break down ADPiv. Negative feed back from serotonin that inhibits andblocks the action of ADPv. Development of blood clot isolates the area iii. Coagulation Phase1. Formation of fibrin2. Begins 30 seconds or more after the injury 3. Coagulation = blood clotting4. Cascade reactions are chain reactions of enzymes and proenzymesa. Make 3 pathwaysb. Convert
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