Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
30 Cards in this Set
- Front
- Back
What is Hemostatic Mechanism? |
-Complex series of biochemical & physiological events that are activated to stop the loss of blood when vessels are damaged.
-Prevents minor bumps and bruises of daily life from being fatal! |
|
Hemostasis combination of 3 separate mechanisms are:
|
1. Response of blood vessels to injury.
2. Platelet activation 3. Stimulation of clotting cascade. |
|
Name 2 resons why vessels constrict:
|
Caused by:
1. Local muscle fiber stimulation. 2. Reflex of the sympathetic nervous system. |
|
What is Vascular Response?
|
When artery/arteriole is damaged, the varying amounts of smooth muscles within vessels contract almost immediately.
|
|
What is the life span of Platelets?
|
5-10 days
|
|
Platelets are only exposed to what 3 areas?
|
1. Endothelium
2. Endocardium 3. Sinusoids of liver |
|
Platelets release what 3 products as they aggregate?
What does each do? |
1. Adenosine diphosphate (ADP) = stimulates rapid aggregation & adherence
2. Histamine & Serotonin = maintains vasoconstriction after trauma and in small vessels may control hemorrhage. 3. Phosopholipid (PLatelet Factor 3 or PF3) = important in activation of coagulation cascade and clot retraction. |
|
Blood clots gradually shrink over a period of time releasing trapped serum called what?
|
Syneresis
(process is to decrease defect in blood vessel) |
|
What is the substance from platelets responsible for clot retraction?
|
Thrombosthenin
|
|
What is the Coagulation Mechanism Response?
|
Result of numerous inactivated soluable proteins and other substances present in the blood stream become activated changing the physical form of blood in the region from a liquid to a semisolid substance. (these proteins & substances are: Clotting Factors)
|
|
Clot formation is activated by one of 2 pathways. What are the 2 pathways?
|
1. Intrinsic Pathway (within)
2. Extrinsic Pathway (outside) (both effect of "Common Pathway" converting soluble fibrinogen into an insoluble fibrin strands which form a meshwork and attaches to a platelet plug) |
|
What is the Intrinsic Pathway? Give an example
|
-Consist of factors present WITHIN the blood steam.
-These are activated *without* tissue contact. EX: indwelling catheter |
|
What is the Extrinsic Pathway? Give an example
|
-Activated by contact w/ cells and tissue fluid OUTSIDE the vessel
-Tissue thromboplastin (factorIII) important in this pathway. |
|
How long does it take for clot formation?
|
Takes place in as little as 15 seconds and (if not physically disrupted) completed in 5 minutes.
|
|
What is the job of Enzymes in clot formation?
|
-They are present to destroy each clotting factor activated.
-Prevents the coagulation from spreading throughout the vascular system. |
|
What does Fibrinolysin do?
|
Its another enzyme that is present to begin degrading the clot as it is formed.
|
|
What is Clot Formation?
|
A dynamic balance between stimulation for formation and removal.
(after damaged vessel is repaired, the clot will be removed) |
|
Define Thrombus:
|
A clot within a vessel if it stays at the formation site.
|
|
Define Embolus:
|
If a clot detaches into the blood stream it becomes an (Thromboembolus)
**Thrombi & Emboli are common causes of heart attacks and strokes in humans and animals. |
|
Define Eschar:
|
A blood clot that forms on the skin surface and dries. (SCAB)
|
|
Define Hemostatic Defects:
|
Leads to excessive loss of blood and are potentially fatal.
|
|
What causes Hemostatic Defects?
|
**May be either HEREDITARY or AQUIRED defects in coagulation proteins, platelets, or the vasculature.
|
|
Clinical signs of Hemostatic Defects:
|
-Most bleeding disorders in veterinary species are secondary to a disease process.*
Clinical Signs: spotting, nosebleeds, melena, prolonged bleeding @ injection or incision sites |
|
HEMOPHILIA A
(deficiency of Factor VIII) |
HEMOPHILIA A (deficiency of factor VIII): an abnormality in the intrinsic system. (Prothrombin consumption is deficient)
|
|
The following are Hereditary Coagulation Defects:
|
5 are listed
|
|
HEMOPHILIA B
(deficiency of Factor IX) |
HEMOPHILIA B (deficiency of Factor IX): AKA: CHRISTMAS DISEASE
-Recessive trait, seen less freq. than hemophilia A |
|
FACTOR VII deficiency
|
-Affected animals usually do NOT have serious bleeding tendencies
-*Note: Excessive bleeding can occur during surgeries! |
|
FACTOR XI deficiency
|
-Dogs & Cattle
-Characterized by minor bleeding episodes -Protracted bleeding in association w/ surgery |
|
VON WILLEBRAND'S Disease
|
**MOST COMMON HEMOSTATIC DEFECT!
-Not a clotting factor defect -Lack of protein available for proteins to attach to endothelium preventing/slowing clot formation -Clinical Signs: Excessive bleeding following minor surgery, nosebleeds, gingival, penile, vaginal bleeding, GI bleeding w/ or w/o diarrhea, hematuria, prolonged estral/postpartum bleeding and umbilical cord @ birth, hematoma, lameness |
|
Acquired Coagulation Defects
|
**Most often encountered by veterinarians
|