Platelets

Question 1

What are the 3 components needed for hemostasis?

Answer 1

• Vessel wall
• Platelets
• Coagulation system

Question 2

What are platelets responsible for?

Answer 2

Primary hemostasis

Question 3

What are the 4 steps of primary hemostasis

Answer 3

1. Adhesion to collagen at the site of vascular injury
2. Additional platelets to plug the leak of the wall
3. Release of platelet contents to promote hemostasis
4. Provision of a phospholipid surface to assemble proteins of the coagulation cascade

Question 4

Describe step 1…

-Adhesion of platelets to collagen at the site of vascular injury

Answer 4

• When the endometrium is disrupted, the collagen is exposed

- Platelets adhere to endothelial cells based on reaction between glycoprotein 1B and VonWillebrand Factor

Question 5

Describe Step 2…

-Aggregation of additional platelets to “plug” the leak in the blood vessel

Answer 5

• Platelets activate other platelets to bind soluble molecules such as fibrinogen
• Fibrinogen acts like a bridge between the interacting platelets and the activated platelets at the binding site

Question 6

What are platelets rich in that promotes hemostasis?

Answer 6

• ADP
• ATP
• Calcium
• Enzymes
• Clotting factors

Question 7

The combination of what 2 things results in vasoconstriction?

Answer 7

• Clotting factors

- Prostaglandin Thromboxane A2

Question 8

What is the point of vasoconstriction?

Answer 8

Controls bleeding

Question 9

What is the goal of the phospholipid membrane?

Answer 9

-Organizes and promotes interactions and clotting factors

Question 10

What does the assembly of a complex do?

Answer 10

-Enhances hemostatic activity and stops bleeding

Question 11

When is the patient at risk for hemorrhage?

Answer 11

If they have problems with platelets, wall, or cascade

Question 12

What is the normal platelet count?

Answer 12

150,000-400,000

Question 13

When are platelet numbers a problem with surgery and trauma?

Answer 13

Under 50

Question 14

When are platelet numbers a problem with spontaneous bleeding?

Answer 14

Under 20