SOK Physiology for Nursing Blood-3 (10-2024) PDF

Physiology of Blood (Part-3) Introductory Case A 30-year-old male. Pallor & easy fatigability. Hemoglobin content was 6.5 gm%. Blood transfusion was indicated. Learning Objectives At the end of this lecture, you should be able to: Enumerate functions of platelets. Define purpura and list...

Physiology of Blood (Part-3) Introductory Case A 30-year-old male. Pallor & easy fatigability. Hemoglobin content was 6.5 gm%. Blood transfusion was indicated. Learning Objectives At the end of this lecture, you should be able to: Enumerate functions of platelets. Define purpura and list its causes. Clarify erythroblastosis fetalis. Explain blood transfusion (indications, precautions & complications). Platelets (Thrombocytes) & Hemostasis  Platelets (Thrombocytes) Normal Functions Definition Purpura life span Local vascular spasm: release VC substances. Normal Platelet adherence: one platelet sticks to injured count blood vessel wall. Oval non- Platelet aggregation: additional platelets stick to nucleated originally adherent platelets to form plug. 5-10 days discs Plug formation. (short) Origin Blood clot: by release of stored clotting factors. Clot retraction. Healing of injured vessel wall: release growth Megakaryocyte factor. 150,000 -350,000/mm3 in bone marrow Dissolve clot (fibrinolysis). (average 250,000/ml) Figure-1: Platelet plug formation. Figure-2: Platelet function.  Purpura Definition Bleeding time Causes Definition: time needed for bleeding from small wound Hemorrhagic disease characterized to stop without coagulation. by bleeding under the skin & Defect in platelets: Normal time: 1-4 minutes. mucous membrane in the form of: Thrombocytopenic purpura: It measures the integrity of Petechiae: small hemorrhage decreased platelet count blood vessel wall & platelet (pin point or pinhead). e.g., bone marrow lesion. functions. Ecchymosis: large hemorrhage. Thrombasthenic purpura: It is prolonged in purpura. defect in platelet function. Defect in blood vessel wall e.g., vitamin C deficiency. Figure-3: Purpura.  Bleeding time: use a filter paper to wipe the blood each 30 seconds after pin pricking until bleeding stops i.e., it is time from pin pricking till stoppage of bleeding without clotting. Figure-4: Bleeding time.  Hemostasis Definition Mechanism Hemophilia A physiological process by means Vasoconstriction (local vascular spasm). of which bleeding from a small Platelet reactions (platelet Plug formation). vascular injury is stopped Coagulation mechanism (clot formation)  Blood Clotting (Blood Coagulation): Definition: blood clot is a fibrin network entangling blood cells. Mechanism: Intrinsic mechanism: depends on blood component only (4-8 minutes). Extrinsic mechanism: needs tissue factor derived from tissues outside blood component (20-40 Figure-5: Blood clot. sec).  Clotting factors Anticoagulants Definition: they are factors that share in blood Definition: they are factors that clot formation. prevent blood clot formation. Characters: They include: are plasma proteins, mostly -globulins Addition of heparin. formed by the liver. Decreasing Ca2+ (clotting factor IV) are proteolytic enzymes, present in blood in by Na citrate 3.8 %. an inactive form. Collection of blood in silicon coated when activated, they activate other inactive tubes. enzymes, resulting in a cascade of reactions, Cooling of blood. which end in clot formation. Removal of fibrinogen by steering are given numbers (I-XIII, no VI). with glass rods. are given “a” when they are activated e.g., Xa. Table-1: Clotting factors & anticoagulants. Figure-6: Clotting mechanism.  Hemophilia: Characters: Hemorrhagic recessive sex-linked disease. Carried by female & affects male. Causes severe bleeding after trauma. Types: Hemophilia A: ↓ VIII. Hemophilia B: ↓ IX. Hemophilia C: ↓ XI. Clotting time (normally 4- 8 minutes): is prolonged in hemophilia. Figure-7: Hemophilia. Blood Groups  Blood Groups Dr Khaled A Abulfadle According to According to ABO system Rh system Rh positive people (85% of population) have Rh- agglutinogens (D-antigens) on RBCs membrane. Rh negative people (15% of population) have no Rh- agglutinogens on RBCs membrane. Table-2: Types of blood groups according to ABO system.  Erythroblastosis Fetalis Dr Khaled A Abulfadle Pathophysiology Prevention Treatment Gradual replacements Rh negative female should never receive of baby’s blood with Rh positive blood. Rh negative group O When this female delivers 1st Rh-positive fetus, anti-D antibodies are given to the mother (during 48 hours after each delivery) to neutralize D-antigen of fetal RBCs transmitted to her, so prevent formation of Rh antibodies.  1 When Rh +ve male married Rh -ve female, the fetus may be Rh +ve. Only during delivery, large numbers of Rh +ve fetal RBCs enter 2 circulation of mother & sensitize her immune system to produce anti-D Pathophysiology of agglutinins. Erythroblastosis Fetalis 3 During the following pregnancy, these antibodies (IgG) cross placenta to Rh +ve 2nd fetus causing agglutination of his RBCs & hemolysis. So, 2nd or 3rd fetus is born anemic, jaundiced (excessive formation of 4 bilirubin which may cross blood-brain barrier of fetus as it is not well- developed causing brain damage i.e., Kernicterus) or born dead. Usually, 1st baby should not be affected except if the mother is 5 sensitized by previous transfusion of Rh +ve blood. Figure-8: Pathogenesis of erythroblastosis fetalis. Blood Transfusion  Blood Transfusion Dr Khaled A Abulfadle Indications Changes occur Complications in stored blood Precautions Of incompatible Of compatible blood transfusion blood transfusion e.g., blood from e.g., blood from group A to group B group B to group B Abnormal blood contents. Massive blood transfusion. 2, 3-DPG = 2, 3-diphosphoglycerate  Compatible & incompatible blood transfusion: Recipient’s plasma should not contain agglutinin against the donor’s red cells. Group O is a universal donor as RBCs of this group contain no antigens. Group AB is a universal recipient as the plasma of this group does not contain anti-A or anti-B. Figure-9: Compatible & incompatible blood transfusion.  Complications of Incompatible Blood Transfusion i.e., (received from Incompatibility Incompatible transfusion the donor) Summary At the end of this lecture, you should be able to: Enumerate functions of platelets. Define purpura and list its causes. Clarify erythroblastosis fetalis. Explain blood transfusion (indications, precautions & complications). Examples of Self-Assessment Questions Single Best Answer (SBAs) 1-Which of the following is the normal platelet count? 3000/mm3. 30000/mm3. 300000/mm3. 3000000/mm3. 2-Which of the following is the normal thrombocyte life span? 2 days. 10 days. 23 days. 32 days. 3-Which of the following is the most numerous blood group according to ABO system? A blood group. B blood group. AB blood group. O blood group. 4-Which percentage out of population represents Rh positive people? 30%. 55%. 85%. 90%. 5-Incompatible blood transfusion causes which of the following? Hypertension. Ischemic pain. Iron overload. Infection. 6-Massive compatible blood transfusion causes which of the following? Hypokalemia. Hypocalcemia. Increased blood sodium. Decreased blood iron. 7-Blood transfusion is indicated in which condition? With 5% decrease in blood volume. With hemoglobin content 11 gm/dl. With marked decrease in platelet count. With RBCs count 5 million/mm3. 8-Which of the following is a precaution for blood transfusion? The blood transfused is free from infectious diseases. Hemoglobin content of the donor is 8 gm/dl. Blood groups of the donor and recipient are incompatible. Blood used for transfusion was stored in blood bank at 37oC. 9-Stored blood in blood banks has an increase in which of the following? RBCs count. K+ level. Platelet count. Dextrose level. 10-Which of the following is a complication of incompatible blood transfusion? Reduced blood viscosity. Decreased cardiac work. Hypertension. Acute renal failure. 11-Which blood group has surface antigen “B” and antibodies “Anti-A” in plasma? Blood group A. Blood group B. Blood group AB. Blood group O. 12-Which blood group is a universal blood donor? Blood group A. Blood group B. Blood group AB. Blood group O. 13-Thrombocytes has which one of the following features? Formed by megakaryocyte in bone marrow. Normal count is 25000/mm3. Has no role in clot formation. Oval nucleated discs. 14-Purpura is caused by deficiency in which of the following? RBCs. Platelets. Eosinophils. Neutrophils. 15-Which of the following is a character of purpura? Recessive X-linked disease. Vitamin C deficiency causes it. Prolonged clotting time. Decreased clotting factor VIII. 16-Which value represents normal bleeding time? 15 sec. 30 sec. 3 min. 10 min. 17-Which of the following causes anticoagulant effect? Removal of heparin from blood. Collection of blood in a tube. Adding calcium to blood. Cooling of blood. 18-Most of clotting factors are formed from which of the following plasma proteins? Albumin. Alpha globulin. Beta globulin. Gamma globulin. 19-Which of the following is the main site of synthesis of clotting factors? Kidney. Liver. Spleen. Brain. 20-Hemophilia C is due to deficiency of which clotting factor? Factor VIII. Factor IX. Factor XI. Factor XIII. 21-Which blood group is a universal recipient? Blood group A. Blood group B. Blood group AB. Blood group O. 22-Erythroblastosis fetalis may occur in which one of the following conditions? Mother Rh +ve, father Rh +ve, baby Rh +ve. Mother Rh +ve, father Rh +ve, baby Rh -ve. Mother Rh –ve, father Rh –ve, baby Rh -ve. Mother Rh –ve, father Rh +ve, baby Rh +ve. 23-Erythroblastosis fetalis is treated by transfusion of which blood group? Rh -ve group O. Rh -ve group AB. Rh +ve group AB. Rh +ve group O. 24-Which of the following is the normal distribution of blood groups in the population? Group A > group B > group AB > group O. Group A > group AB > group O > group B. Group O > group A > group B > group AB. Group O > group B > group AB > group A. 25-For a person to donate blood, which of the following is the least time should be present from the previous blood donation? 3 days. 3 weeks. 3 months. 3 years. 26-Which of the following is considered incompatible blood transfusion? The donor is blood group A and the recipient is blood group A. The donor is blood group B and the recipient is blood group B. The donor is blood group O and the recipient is blood group AB. The donor is blood group AB and the recipient is blood group A. 27-True (T) or false (F): Platelets share in healing of injured vessel wall. Thrombasthenic purpura is caused by decreased platelet count. Bleeding time is prolonged in purpura. Clotting time measures the integrity of blood vessel wall & platelet functions. Intrinsic mechanism of blood clotting is shorter in duration than the extrinsic mechanism. Heparin is a clotting factor. Clotting factors are proteolytic enzymes, present in blood in an active form. Hemophilia A occurs due to deficiency in clotting factor VIII. Blood group AB is a universal blood recipient. Erythroblastosis fetalis occurs when Rh positive female married Rh positive male and has Rh negative baby. Exchange blood transfusion is indicated in erythroblastosis fetalis. Blood transfusion is indicated if hemoglobin content in an adult female is 10 gm/dl. Blood is warmed before being transfused Blood grouping should be confirmed by double cross matching test. Blood group AB can donate blood to blood group O. Massive blood transfusion causes iron overload. Hypercalcemia is a complication of massive blood transfusion. Answer Key SBAs SBAs Answer Key: 1-C. 2-B. 3-D. 4-C. 5-B. 6-B. 7-C. 8-A. 9-B. 10-D. 11-B. 12-D. 13-A. 14-B. 15-B. 16-C. 17-D. 18-C. 19-B. 20-C. 21-C. 22-D. 23-A. 24-C. 25-C. 26-D. Case Discussion A 30-year-old male. Pallor & easy fatigability. Hemoglobin content was 6.5 gm%. Blood transfusion was indicated. References