Lesson Plan #98 Flashcards
Stopping of blood clotting
- Process involving coagulation of blood to prevent ++ bleeding d/t vascular injury
- Involves the conversion of inactive substances to active ones
Hemostasis
- Part of hemostasis
- Describes clotting of plasma proteins (specifically fibrinogen)
Coagulation
- Protein produced by the liver
- Required in hemostasis (clotting protein)
- Soluble protein
- Inactive form
- Must be activated by thrombin (enzyme) & converted to fibrin to form a clot
Fibrinogen
- Activated form of fibrinogen
- Forms insoluble blood clot
Fibrin
- Source: bone marrow
- Differentiation of platelets regulated by Thrombopoietin (liver & kidneys)
- Thrombocytes originate from hemocytoblasts
Thrombocytes
Production of platelets (4 stages)
- hemocytoblast
- megakaryoblast
- megakaryocytes
- thrombocytes
3 phases of hemostasis
- Vascular spasm
- Platelet plug formation
- Coagulation
Vasoconstriction of injuries bv’s decrease BF & helps slow bleeding
Vascular spasm
Platelet aggregation seals break in bv wall
Platelet plug formation
Blood changed from liquid to gel (blood clot)
Coagulation
Blood clotting is triggered by vascular injury by 2 pathways
Intrinsic
Extrinsic
Pathways:
- When damage to bv’s expose collagen fibers- impale circulating platelets
- Injured platelets release PF3- activates other factors
Intrinsic pathways
Pathways:
- When damage to tissues releases tissue factor (TF)
- Shortcut- bypasses several rxns found in intrinsic pathways
Extrinsic pathway
A process in which blood clots are slowly dissolved
Fibrinolysis
Purpose of fibrinolysis
-Removal of blood clots when bv healing is complete
-Removes small, unnecessary clots that form w/in bv’s
.clean-up mechanism
- Clot attached to walls of a bv
- Partially or completely block a bv
Thrombus (thrombi)
- A freely moving particle (ex.thrombus) that has broken free
- Fat emboli (bone marrow), air emboli (lungs) & amniotic fluid emboli (during childbirth)
- Travel in blood stream & may lodge in a small bv or dissolve naturally
Embolus (emboli)
- Associated w/ unnecessary intravascular blood clotting
- Conditions predisposing to thrombus formation:
- severe burns: loss of plasma proteins
- inflammation: release of coagulating factors
Thromboembolytic disorder
- Severe decrease in no. Of circulating platelets
- insufficient for hemostasis
- Results in:
- Spontaneous bleeding
- Appearance of petechiae on skin (marks on skin/acne)
Thrombocytopenia
Bleeding d/t impaired liver fxn:
Healthy liver?
&
Unhealthy liver?
Healthy liver:
-produces clotting factors that activate coagulation
Unhealthy liver:
- Deficient production of clotting factors
- Can lead to severe bleeding
Deficient Vt.K leads to?
- Prolonged clotting times
- Easy bruising
- Group of hereditary disorders
- Clotting factors defective or absent (various types)
- No cure
- May be medically managed
- S/S:
- Prolonged bleeding
- Bruising
- Jt pain
Hemophilia
Thromboembolytic disorder vs Bleeding disorder
Throm:
- BF obstruction causes ischemia & hypoxia
- May lead to necrosis
Bleeding:
-++ blood loss leads to hypovolemic shock