PRIMARY HEMOSTASIS

Question 1

• Contact of platelets with the sub endothelium (collagen, fibers, fibronectin) and their adhesion to it
• tissue occurs because vWF (in the plasma that binds platelets to exposed endothelium) is deposited to the injured tissues

Answer 1

Platelet adhesion

Question 2

•platelets undergo shape changes with the intrusion of numerous pseudopods due to contraction of microtubules
•plated granules move to the center of the platelet and fuse to the open canalicular system connected to the outer portion of the platelet
•the contents of the granules (ADP, serotonin, b-thromboglobulin, factor IV, vWF, PDGF) are released outside

Answer 2

Platelet Secretion

Question 3

•crosslinking of platelets through active GP2B/3A receptors with fibrinogen bridges
•platelet stimulating agents (collagen, ADP, epinephrine, thrombin) binds the platelets, causing them to adhere to one another

Answer 3

Platelet aggregation

Question 5

Laboratory for primary hemostasis

Answer 5

1. Platelet count
2. Platelet count estimation
3. Bleeding time
4. Clot retraction
5. Platelet adhesion
6. Platelet aggregation
7. Capillary/fragility test
8. Antiplatelets antibody assay

Question 6

Reasons why plates are hard to count

Answer 6

•platelets adhere to foreign surface (like skin and dried walls of pipets)
•platelets easily disintegrate
•they are hard to differentiate from debris
•platelets are unevenly distributed in the blood because they tend to clump
•significant bleeding usually does not occur until the pain that count is less than 60

Question 7

Platelets are counted in relation to RBCs in the blood smear (not reliable)

Answer 7

Indirect methods

Question 8

Whole blood is diluted with platelet diluting fluid in an RBC pipette and counted in hemocytometer

Answer 8

Direct methods

Question 9

Diluent is made up of sodium oxalate, brilliant cresyl blue, formaline and distilled water

Answer 9

Reese-ecker

Question 10

Then you went is made up of sodium oxalate, 40% formaline and crystal violet

Answer 10

Guy and leake

Question 11

-1% ammonium oxalate
-procedure: same with reese and ecker except that platelets are counted with the use of phase contrast microscope

Answer 11

Brecker-Cronkite

Question 12

Direct (Neubauer counting chamber) Is reported as

Answer 12

%

Question 13

Direct platelet count methods

Answer 13

a. Reese-Ecker
b. Guy and Leake
c. Brecker- Conkrite
d. Unopette
e. Tocantin’s
f. Nygard’s
g. Walker and Sweeney’s
h. Van Allen’s

(RGBUTNWV)

Question 14

Indirect platelet count methods

Answer 14

a. Dameshek
b. Fonio’s
c. Olef’s

(DFO)

Question 15

-to approximate number of platelets per field, examine the thin area of the slide using OIO

Answer 15

Platelet count estimation

Question 16

In a platelet count estimation, A normal blood smear should demonstrate approximately ____ platelets per field

Answer 16

8 to 20

Question 17

0-49,000/uL

Answer 17

Marked decrease

Question 18

50,000 - 99,000/uL

Answer 18

Moderate decrease

Question 19

100,00-149,000/uL

Answer 19

Slight decrease

Question 20

150,000 to 199,000/uL

Answer 20

Low normal

Question 21

200,000 to 400,000/uL

Answer 21

Normal

Question 22

401,000 - 599,000 / uL

Answer 22

Slight increase

Question 23

600,000 - 800,000/uL

Answer 23

Moderate increase

Question 24

•in vivo measurement of platelet adhesion and aggregation
•estimate of the integrity of the platelet plug
•reflects aspects of platelet function

Answer 24

Bleeding time

Question 25

As the platelet count drops below ___ bleeding time increases

Answer 25

100 x 109 per liter

Question 27

Factors which affects bleeding time

Answer 27

1. Elasticity of the cut tissue 2. Ability of the blood vessels to constrict and retract 3. Mechanical and chemical action of platelets in the formation of hemostatic plug

Question 28

Bleeding time is prolonged in the following conditions

Answer 28

1. When the blood places are greatly reduced 2. Injury of capillary Walls 3. Platelet deficiency

Question 29

Thrombocytopenic purpura and acute leukemia

Answer 29

Prolonged bleeding: blood platelets are greatly reduced

Question 30

Scurvy and toxins (snake venom, infection, chemical)

Answer 30

Injury of capillary walls

Question 31

Destructive disease of the liver, HDFN, slightly prolonged severe anemia

Answer 31

Platelet deficiency

Question 32

Methods for bleeding time (DICAMA)

Answer 32

1. Duke's method 2. Modified Ivy's method 3. Copley lalitch method 4. Adelson-Crosby method 5. MacFarlane's method 6. Aspirin intolerance test

Question 33

Best method to assess platelets. It is considered to be the best cleaning test available for platelets role in hemostasis

Answer 33

Modified Ivy's method

Question 34

Same principle with adelson crosby method but it only uses earlobe as the site of puncture

Answer 34

MacFarlane's method

Question 35

Assesses The effect of a standard dose of aspirin on the dukes bleeding time

Answer 35

Aspirin tolerance test

Question 36

•ability updated to contract the formed clot •reflects quality of platelets, number of fibrinogens fibrinolytic activity and PRBC •directly proportional to number of platelets

Answer 36

Clot retraction

Question 37

•in vitro: uses glass bead •amount of adhesion reflects the ability of plts to adhere •The amount of adherence of platelets in a blood sample to a glass surface can be measured by counting the number of platelets before and after exposure to glass beads

Answer 37

Platelet adhesion

Question 38

•principle: Rich platelet plasma treated with known aggregating agent •uses agonists such as: ADH, collagen, epinephrine, snake venom, thrombin, arachidonic acid, and ristocetin (ACESTAR)

Answer 38

Platelet aggregation

Question 39

• tests the stability of the small blood vessels to retain the red cell in their lumen under conditions of stress and trauma

Answer 39

Capillary or fragility test

Question 40

Principal: rich platelet plasma treated with known aggregating agent

Answer 40

Platelet aggregation

Question 41

Principle: by partially obstructing the venous blood, The capillary pressure is increased. This will give rise to intravasation of blood which will be manifested in the form of small hemorrhage called petechiae

Answer 41

Capillary or fragility test

Question 42

Small hemorrhage

Answer 42

Petechiae

Question 43

•complement fixation •lysis of chromium 51-labeled •platelets to platelet bound immunoglobulin •competitive inhibition assay

Answer 43

Antiplatelets antibody assay