Erythrocyte clotting Flashcards
Life span of RBC
Anemias caused by:
Iron deficiency, B12 deficiency, folate deficiency, thalassemia, RBC loss
Erythrocyte metabolism is dependent on ___.
They also require ___.
glucose (glycolysis) (because RBCs do not have mitochondria)
NADPH reducing equivalents for glutathione
Erythrocytes use ___ to reduce ferric iron to ferrous iron.
NADH (from glycolysis)
Erythrocytes use __ to modulate oxygen binding to hemoglobin, which stabilizes deoxy-hemoglobin.
Glucose-6-phosphate dehydrogenase deficiency results in ___.
hemolytic anemia (NADPH keeps glutathione reduced, helps prevent buildup of ROS, low NADPH results in hemolysis, deficiency decreases NADPH)
What are some sources of oxidative stress for red blood cells?
primaquine for malaria, aspirin, sulfonamide antibiotics (folic acid inhibitors), and fava beans
What causes microcytotic anemia?
iron deficiency, lead poisoning, or thalessemia
(They cause impaired hemoglobin synthesis)
Microcytic anemia is also known as hypochromic anemia
What causes macrocytic anemia?
B12 or folate (B9) deficiency
This causes impaired DNA synthesis
Macrocytic anemia is also known as normochromic anemia
What causes normocytic anemia?
Severe bleeding, sickle cell anemia, pyruvate kinase deficiency, or glucose-6-phosphate dehydrogenase deficiency
This causes red blood cell loss
Normocytic anemia is normochromic anemia
The process of clot formation and susequent dissolution
Four major events associated with hemostasis
Vascular constriction, Platelets activated by thrombin and aggregate at injury site, fibrin clot formation: intrinsic and extrinsic pathways, dissolution of clot: action of plasmin
Platelets are derived from ___.
Hormone that controls platelet formation
True or false: Platelets contain mitochondria.
Life span of platelet
Adhesion, aggregation, and activation
adhesion: At damaged site, glycoprotein IA (GPIa) binds collagen and GPIb binds VonWillebrand factor (vWF) that is attached to collagen
Aggregation: glycoprotein IIb/IIIa molecules on platelets bind other platelets through fibrin
Activation: Release of hemostasis chemicals from intracellular granules
Stimulation of platelet membrane receptors triggers activation of platelet membrane phospholipase A2 (PLA2)
Hydrolyzes membrane phospholipids, platelets release arachidonic acid
prostacyclin, major arachidonic acid metabolite formed by vascular cells (potent vasodilator, inhibitor of platelet aggregation)
Platelet-related bleeding disorders
Congenital bleeding disorders:
Bernard-Soulier syndrome: GPIb-IX deficiency causes bleeding disorder
Acquired platelet disorders:
Thrombocytopenia (low platelet count): defective formation of platelets by megakaryocytes, bone marrow neoplasia; excessive destruction of platelets - anti-platelet antibodies
Platelet inhibition drugs
Plavix (inhibits ADP-induced platelet aggregation acting by direct inhibition of adenosine diphosphate (ADP) binding to its receptor and of the subsequent ADP-mediated activation of the glycoprotein GPIIb/IIIa complex
Antiplatelet drugs (examples)
dipyridamole, ticlopidine, clopidogrel (plavix)
Less gastric bleeding than aspirin
inhibits uptake of adenosine, leading to increased platelet A2 receptor stimulation and suppression of ADP receptor action