Unit 4 - Blood Flashcards
Erythropoiesis
Process of producing RBCs in bone marrow
Erythropoietin (EPO)
A hormone secreted by kidney when low O2 in blood
Stimulates eruthropoiesis by red marrow
List 4 roles of thrombin in blood coagulation.
- converts fibrinogen to fibrin
- activates factor Xlll to stabilize fibrin mesh
- acts in positive-feedback fashion to facilitate its own formation
- enhances platelet aggregation
hemostasis
arrest of bleeding from a broken blood vessel (aka stopping of hemorrhage)
3 steps of Hemostasis
- vascular spasm
- formation of platelet plug
- blood coagulation
vascular spasm
when vessel is injured, PARACRINE is released by the endothelial lining of the injured vessel.
Constriction slows blood flow.
formation of platelet plug (3 stages)
- Platelet adhesion
- Platelet reaction
- Platelet aggregation
Formation of platelet plug: adhesion
injury exposes collagen, which causes platelets to stick
Formation of platelet plug: reaction
platelets degranulate releasing:
- serotonin: a vasoconstrictor
- ADP: attracts & degranulates more platelets
- thromboxane A2: promotes aggregation, degranulation, & a vasoconstrictor
Formation of platelet plug: aggregation
aka White Thrombus
What makes up hemoglobin (Hb)?
Globin = 4 polypeptide chains of amino acids (protein)
Each polypeptide chain has a HEME unit
Each hemoglobin molecule can carry 4 O2 molecules
neutrophils
- Leukocyte / WBC
- granulocyte; nuclei w/2-5 lobes
- make up 60-70% of white blood cells
- phagocytic - form NETs
- first defenders
lymphocytes
- WBC
- agranulocyte
- 25-33% of WBC
- large nucleus
- B & T type
- involved in diverse infections & immune responses
monocytes
- agranulocyte
- 3-8% of WBC
- differentiate into macrophages
- phagocytize pathogens & debris
- “present” antigens to activate other immune cells
eosinophils
- granulocyte w/lobed nuclei
- 1-4% of WBC
- respond to allergies & parasitic infections
basophils
- granulocyte w/lots of grans that cover nuclei
- < 1% of WBC
- store heparin & histamine
Factor I
Fibrinogen - soluble plasma protein that converts to Fibrin
Both intrinsic & extrinsic
Factor II
Prothrombin: factor X converts Prothrombin to Thrombin
both intrinsic & extrinsic
What is thrombin?
activates Factor XIII - which stabilizes fibrin meshwork
Factor III
Thromboplastin
released by damaged tissue
Initiates Extrinsic pathway (only)
Factor IV
Ca2+
mineral required in most steps
both intrinsic & extrinsic
Factor V
both intrinsic & extrinsic
Factor VII
extrinsic only
Factor VIII
Anti-hemophilia factor
instrinsic only
deficiency causes Hemophilia A
Factor IX
intrinsic only
Factor X
both
when activated acts as prothrombin activator
Factor XI
intrinsic only
Factor XII
Hageman Factor
initiates fibrinolysis (breakdown of clot)
triggers instrinsic pathway
Factor XIII
fibrin stabilizing factor
inserts cross-links between fibrin threads
both
plasmin
a plasma protein made in liver & present in blood
inactive form is PLASMINOGEN
activated by Factor XII
gets caught in clot; later breaks it down
Stages of Coagulation
- Formation of Prothrombin activator (thru Instrinsic or Extrinsic pathway)
- Conversion of Prothrombin to Thrombin
- Conversion of Fibrinogen to Fibrin
Extrinsic pathway
3 steps
initiated by Factor III - Tissue Thromboplastin -> goes straight to Factor X
Instrinsic pathway
7 steps
initiated by Factor XII - Hageman Factor
Steps – XII, XI, IX, X
common pathway
Factor X -> prothrombin -> thrombin -> fibrinogen -> fibrin Factor XIII (activated by thrombin) -> stabilizes fibrin
fibrinolysis
removal of clot after healing
plasmin breaks down clot
3 chemicals that prevent thrombosis
- heparin
- Tissue Plasminogen Activator (tPA) - from lungs
- Antithrombin III - from liver; deactivates thrombin before it can act on fibrinogen
role of vit K
involved in the synthesis of many clotting factors
Warfarin (drug)
given to prevent clotting
vit K antagonist
interferes w/formation of clotting factors II, VII, IX, X
