Hematology Physiology Flashcards
Where is Iron stored?
1) Hemoglobin/myoglobin
2) Ferritin and Hemosiderin
What transports Iron?
Transferrin
Where is iron absorbed in the GI system?
Proximal duodenum
What transports iron across the apical membrane of a cell in the intestinal wall?
Divalent metal transporter (DMT1)
What transports iron into the blood?
Ferroportin 1
What regulated Ferroportin 1? How does it do this?
1) Hepicidin
2) Causes the degradation of Ferroportin 1 in enterocytes and macrophages
Where is hepicidin synthesized and released?
Liver
Where does heme synthesis take place?
1) Bone marrow and liver
2) Specifically in the mitochondria and cytoplasm
Where do the first three steps of heme synthesis take place
Mitochondria
What is the first step of heme synthesis?
1) Succinyl CoA + Glycine –> Aminolevulinic acid (ALA)
2) Enzyme: ALA synthase
3) Inhibited by glucose
4) Enhanced by Hypoxia, alcohol and barbituates
What is the second step of heme synthesis?
1) ALA –> Porphoblinogen
2) Enzyme: ALA dehydratase
3) Inhibited by Lead
What is the last step of heme synthesis?
1) Protoporphyrin IX –> Heme
2) Enzyme: Ferrochelatase
3) Inhibited by Lead
What steps in heme catabolism take place in the spleen?
1) Heme –> biliverdin (heme oxygenase)
2) Biliverdin –> bilirubin (biliverdin reductase)
What converts conjugated bilirubin to conjugated?
UDP-Gluconyrl transferase
What carries unconjugated bilirubin?
Albumin. It must be carried because it is lipophilic.
What are the different types of hemoglobin?
1) Hemoglobin A (beta chains)
2) Hemoglobin F (gamma chains)
3) Hemoglobin A2 (delta chains)
What chromosome are the alpha like chains on? Beta like?
1) Alpha = 16
2) Beta = 11
What are the steps in the glutathione defense?
1) Reduction of NADP via Glucose 6 phosphate —> 6-Phosphogluconate (G6PD)
2) Reduction of Glutathione via NADPH and Glutathione reductase
3) Conversion of Hydrogen peroxide to water via reduced glutathione and glutathione peroxidase
What are influences on the dissociation of oxygen curve?
CADET face Right
1) CO2
2) Acidic blood (increased H)
3) 2,3 DPG (Bisphosphoglycerate)
4) Exercise
5) Temperature
What are the states of hemoglobin?
1) Tense state (deoxyhemoglobin)
2) Relaxed state (Oxyhemoglobin)
Increased oxygen affinity when one heme gropu binds is known as?
Positive cooperativity
What does 2,3- bisphosphoglycerate bind to?
Deoxygenated hemoglobin (tense state)
What is the components of hemostasis?
1) Primary hemostasis (Hemostatic plug formation)
2) Secondary hemostasis (Fibrin clot formation)
3) Thrombolysis
Describe the steps in hemostaitc plug formation (primary hemostasis)
1) Platelet adhesion (mediated by vWF)
2) Platelet secretion of granules
3) Platelet aggregation
What does von Willebrand Factor mediate?
1) Platelet adhesion in an area of endothelial injury
What are the diferent type of platelet granules and what do they contain?
1) Alpha granules - contain vWF, growth factors V and VIII, and fibrinogen
2) Dense bodes- contain serotonin, ADP, and Calcium (ADP and Ca are important in aggregation)
What does the fibrin clot formation consist of?
1) Extrinsic pathway
2) Intrinsic pathway
Describe the secondary hematostasis extrinsic pathway
1) Activated by tissue factor from endothelial cells
2) Coagulation factor VII is most important
3) Measured by Prothrombin time (PT)
Describe the secondary hematostasis intrinsic pathway
1) Activated by vessel rupture
2) Involves coagulation factors XII, XI, IX, VIII
3) Measured by Partial thromboplastin time
What is measured by PT? PTT?
1) PT (Prothrombin time) = Extrinsic
2) PTT Partial Thromboplastin time)= Intrinsic
What coagulation factors are vitamin K dependent? What drug uses this dependency to treat?
1) Factors II, IX, X, and proteins S and C
2) Warfarin- inhibits vitamin K epoxide reductase
What is the goal of both the intrinsic and extrinsic pathway of fibrin clot formation?
1) To activate factor X which will convert prothrombin to thrombin
What does thrombin do?
1) Thrombin converts fibrinogen to fibrin
2) Fibrin acts as the cement for the platelet plug
What is important about coagulation factor VIII?
It helps stabilize and activate coagulation X
What is dependent upon thrombin levels to be activated?
Thrombin activated fibrinolysis inhibitor (TAFI)
What is the major effector of fibrinolysis? What activates it?
1) Plasmin
2) tissue plasminogen activator
What does plasmin do?
1) Degrades fibrin
2) Degrades coagulation factors V and VIII
What is the function of tPA?
1) tPA activates plasminogen to plasmin
2) Plasmin is involved with the cleavage of fibrin
What can cause a decreased Sedimentation rate?
1) Polycythemia
2) Sickle cell anemia
3) Congestive heart failure
4) Microcytosis
What is the site links platelets together? What increases the amount present?
1) GpIIb/IIIa
2) Adenosine
How do platelets bind to vWF?
1) Gp1b receptor
How is bilirubin taken up in the liver? Excreted?
1) Passive
2) Active transport (MRP2)
What is the normal P50 for hemoglobin? Myoglobin?
1) pO2 of 26 mmHg
2) pO2 of 1 mmHg
Describe the size of the following:
1) Petechiae
2) Purpuraee
3) Ecchymoses
1) Less than 5 mm in diameter
2) 5cm to 1 cm
3) >1cm
