Module 1: Hematology Physiology Flashcards
T or F: All individuals produce antibodies to the AB carbohydrate antigen that they lack.
T
ABO blood group is based on carbohydrate antigens present on RBC membrane either as _______ or ________.
Glycoprotein; Glycosphingolipids
Predict the blood type of the following: 1. Ag - - Ab antiA, antiB 2. Ag A Ab antiB 3. Ag B Ab antiA 4. Ag A, B Ab - -
- O
- A
- B
- AB
Why are agglutinins produced in people who do not have the respective agglutinogens in their red blood cells?
Small amounts of these agglutinogens enter through food and bacteria which initiate the production of agglutinins
Rh blood group has 6 antigens. These are..
C, D, E, c, d, e
Most widely prevalent among the 6 Rh antigens
D
T or F: Hemolytic disease of the newborn usually manifests i. The second Rh+ baby.
T
Two ways of identifying blood types
Forward
Reverse
Identify antigen by antisera
Forward typing
Identify isoagglutinin in serum
Reverse typing
Matches donor blood unit to recipient’s blood
Cross-matching
T or F: Cross-matching should always be done even in mergency cases.
F, may not be done in emergency cases (give type-specific)
Blood transfusion products
Whole blood Packed red blood cells Platelet concentrate Fresh frozen plasma Cryosupernate Cryoprecipitate
Increases oxygen-carrying capacity
Whole blood; Packed red blood cells
T or F: Whole blood is ideal for cases of acute hemorrhage of more than 25% of blood volume.
T
T or F: Packed red blood is given to patients with anemia but without symptoms.
F, should be given to those with anemia and symptoms (dizziness, inc heart rate, difficulty breathing)
Reduces risk of mucosal bleeding
Platelet concentrates
Thresholds for transfusion:
Patient w/o fever or infection
Patient w/ fever or infection
Undergoing invasive procedure
5,000
10,000
50,000
Contains stable coagulation factors and plasma proteins
Fresh frozen plasma
These inactivate factors V and VIII
Protein C
Used for correction of coagulopathies including rapid reversal of warfarin, supplying deficient plasma proteins, treatment of TTP
Fresh frozen plasma
Supplies fibrinogen, factor VIII and von Willebrand factor
Cryoprecipitate
Each unit of cryoprecipitate contains ____ units of factor VIII
80
Contains factor IX
Cryosupernate
Adverse reactions to transfusion can be..
Immunologic
Non immunologic
Infections
Immunologic reactions to transfusion?
Febrile nonhemolytic transfusion reactions Allergic reactions Anaphylaxis Graft versus host disease Transfusion-related acute lung injury Posttransfusion purpura
Non immunologic reactions to transfusion:
Fluid overload Hypothermia Electrolyte imbalances Iron overload Hypotensive reactions Immunomodulation
Infections related to transfusion?
Viral (hepB/C, HIV, CMV etc)
Bacterial contamination
Aids in prevention of bloodloss
Hemostasis
Stages of hemostasis
Reflex vasoconstriction
Primary hemostasis
Secondary hemostasis
Clot retraction or Clot dissolution
Results in immediate reduction in bleeding
Reflex vasoconstriction
Mechanisms of reflex vasoconstriction
Local myogenic spasm-strongest contributor
Local autocoid factors from platelets and injured tissues
Nervous reflexes
Formation of platelet plug
Primary hemostasis
Responsible for hemostasis of small vessels
Primary hemostasis
Primary hemostasis involves..
Platelets (key player)
Blood vessel wall
VWF
Platelets are also called
Thrombocytes
Platelets originate from
Megakaryocytes
T or F: Platelets can reproduce.
F
Normal platelet count
150,000 to 450,000
Function in platelets: actin and myosin fibers
Contraction (also thrombosthenin)
Function in platelets: ER and golgi
Calcium storage
Function in platelets: mitochondria
Produces ATP and ADP
Function: Fibrin-stabilizing factor
Stabilizes fibrin network
Function in platelets: surface glycoproteins
Causes platelet adherence to injured tissue and collagen
Stages in the formation of platelet plug
Platelet adhesion
Platelet activation
Platelet aggregation
Platelet adhesion
Platelets come in contact with exposed subendothelium
Platelets secrete these in their membranes:
Glycoprotein Ib-IX - bind vWF
Glycoprotein Ia/IIb - bind collagen
Platelet activation
Platelet develops pseudopods
Platelets release thromboxane A2, ADP, PAF and serotonin which activates other platelets
Platelet activate its collagen receptor
Glycoprotein IIb/IIIA after vWF binds to Gp Ib
Platelet aggregation
Fibrinogen in the blood ( and vWF in the subendothelium) bind to the platelet receptor glycoprotein IIb/IIIA
Formation of loose platelet plug
Fibrin fibers strengthen platelet plug
If platelet count <50,000
Bleeding
If platelet count <10,000
May be lethal
Formation of fibrin through the coagulation cascade
Secondary hemostasis
Coagulation cascade is divided into
Extrinsic pathway
Intrinsic pathway
Factor I
Fibrinogen
Factor II
Prothrombin
Factor III
Tissue factor
Factor IV
Calcium
Factor V
Proaccelerin; labile factor
Factor VII
Serum prothrombin conversion accelerator; stable factor
Factor VIII
Antihemophilic factor A
Factor IX
Antihemophilic factor B; Christmas factor
Factor X
Stuart factor
Factor XI
Plasma thromboplastin antecedent; antihemophilic factor C
Factor XII
Hageman factor
Factor XIII
Fibrin-stabilizing factor
Prekallikrein
Fletcher factor
High-molecular weight kininogen
Fitzgerald factor
Initiates coagulation cascade
Extrinsic pathway
Amplifies the cascade
Intrinsic pathway
Extrinsic pathway: Clotting can occur in __ sec.
15
Intrinsic pathway: Clotting occurs in __ min
1-6
In which part of the coagulation cascade does the intrinsic and extrinsic pathways converge?
Factor Xa-mediated generation of thrombin from prothrombin
During clot retraction, fibrin clot is invaded by _______ which subsequently form _________ around the clot.
Fibroblasts; connective tissue
T or F: Calcium from platelet stores also contribute to clot retraction.
T
Mediated by anticoagulant and thrombolytic mechanisms
Clot dissolution
What are the factors involved in the coagulation cascade?
Calcium
Vit K
Anticoagulant mechanisms
T or F: Calcium is involved in ALL steps in the cascade.
F, except the first two steps in the intrinsic pathway
Required to produce prothrombin in the liver
Vit K
Anticoagulant mechanisms
Endothelium
Intravascular anticoagulants
Lysis of blood clot
Binds thrombin thereby reducing free thrombin
Thrombomodulin
Inactivates thrombin
Antithrombin III
Increases the activity of antithrombin III hundredfold to thousandfold
Heparin
T or F: Our body has high concentrations of heparin.
F, low
Give some causes of severe bleeding
Liver diseases
Vit K deficiency
Hemophilia A
Hemophilia B
Factor VIII deficiency
Hemophilia A
Factor IX deficiency
Hemophilia B
Causes of excess coagulation
Protein C and S deficiency
Disseminated intravascular hemolysis
Deficiency of hemoglobin in the blood either from too few RBCs or too little hemoglobin
Anemia
Blood loss anemia: morphology of RBCs?
Acute: normal
Chronic: microcytic, hypochromic
What time of anemia is caused by Vit B12 deficiency?
Megaloblastic anemia
Iron deficiency anemia: RBC morohology?
Microcytic, hypochromic
What type of anemia is caused by failure of the bone marrow activity?
Aplastic anemia
Rapid destruction of RBCs due to abnormal morphology or from attack of antibodies against RBCs
Hemolytic anemia
Causes of hemolytic anemia
Hereditary spherocytosis
Sickle cell anemia
Erythroblastosis fetalis
Excess red blood cells
Polycythemia
Polycythemia causes increased blood viscosity which leads to
Cyanosis/plethora, strokes
Types of polycythemia
Physiologic: occurs in high altitudes, smokers
Polycythemia vera: genetic abnormality inRBC precursors
Hypersensitivity reactions
Types I, II, III, IV
Most common among the hypersensitivity reactions
Type I
Immune reactants for each type
I- IgE
II and III- IgG
IV- TH1 cells, TH2 cells, CTL
Antigen for Type II?
Cell or matrix-associated antigen
*other types are soluble antigens, except Type IV ( CTL) - cell associated antigen
Mast cell activation
Type I
Macrophage activation
Type IV (TH1 cells)
Eosinophil activation
Type IV (TH2 cells)
Cytotoxicity
Type IV (CTL)
FcR+ cells
Type II and III
Type I: Example of hypersensitivity reaction
Allergic rhinitis
Asthma
Systemic anaphylaxis
Type II: Examples of hypersensitivity reactions
Drug allergies (eg. Penicillin)
Type III: Examples of hypersensitivity reactions
Serum sickness
Arthus reaction
Type IV: Examples of hypersensitivity reactions
TH1: contact dermatitis, tuberculin reaction
TH2: chronic asthma, chronic allergic rhinitis
CTL: contact dermatitis
Immunodeficiency can be
Congenital
Acquired