Chapter 17.3 - Forming clot

Question 1

What are platelets made off?

Answer 1

Small fragments of megakaryocytes

Question 2

What is thrombopoietin?

Answer 2

The formation of platelets

Question 3

How does a platelet look like?

Answer 3

Blue-staining outer region with purple granules

Question 4

What do the granules contain in platelets?

Answer 4

Serotonin, Ca2+, enzymes, ADP and PDGF

Question 5

What is hemostasis?

Answer 5

Fast series of reactions for stoppage of bleeding

Question 6

Which three steps are involved with hemostasis

Answer 6

Vascular spasm, platelet plug formation, coagulation (blood clotting)

Question 7

What is the tunica intima?

Answer 7

The innermost layer of the blood vessel wall made of simple squamous epithelium

Question 8

What is the tunica media?

Answer 8

Middle layer of the blood vessel wall composed of smooth muscle and sheets of elastin

Question 9

Where are the vasomotor nerve fibers in the tunica media for?

Answer 9

Vasoconstriction and vasodilation

Question 10

What is the tunica externa (adventitia)?

Answer 10

The outermost layer of the blood vessel wall composed of loose collagen fibers

Question 11

What is the vasa vasorum?

Answer 11

System of tiny blood vessels found in larger vessels

Question 12

What is vascular spasm?

Answer 12

Vessel responds to injury with vasoconstriction

Question 13

What triggers vascular spasm?

Answer 13

• Direct injury to vascular smooth muscle
• Chemicals released by endothelial cells and platelets
• Reflexes initiatied by local pain receptors

Question 14

What is platelet plug formation?

Answer 14

Platelets stick to collagen fibers that are exposed when vessels are damaged

Question 15

What prevents platelet sticking?

Answer 15

No collagen and prostacyclins

Question 16

What does the von Willebrand factor

Answer 16

Helps to stabilize platelet-collagen adhesion

Question 17

What is the function of the released chemical messenger of ADP in an activated platelet?

Answer 17

More platelets to stick and release their contents

Question 18

Which chemical messengers of activated platelets enhance vascular spasm and platelet aggregation?

Answer 18

Serotonin and thromboxane A2

Question 19

What do they call the following concept: as more platelets stick,
they release more chemicals, which cause more
platelets to stick and release more chemicals

Answer 19

Postive feedback cycle

Question 20

What are platelet plugs fine for?

Answer 20

Small vessel tears

Question 21

What does coagulation do?

Answer 21

Reinforces platelet plug with fibrin threads

Question 22

How are clotting factors activated?

Answer 22

They are turned into enzymes by clipping off a piece of the protein, changing shape

Question 23

What are the three phases of coagulation?

Answer 23

1. Prothrombin activator is formed
2. prothrombin is converted into thrombin
3. Thrombin catalyzes te joining of fibrinogen to form a fibrin mesh

Question 24

How ends the intrinsic or extrinsic pathway?

Answer 24

The activation of factor X which then complexes with Ca2+, platelets and factor V to form prothrombin activator

Question 25

How is the intrinsic pathway triggered?

Answer 25

By negatively charged surfaces such as activated platelets, collagen, or even glass of a test tube

Question 26

How is the extrinsic pathway triggered

Answer 26

By exposure to tissue factor (TF); factor III

Question 27

What is the name for clotting factors?

Answer 27

Procoagulants

Question 28

What are important plasma proteins in coagulation?

Answer 28

I to XIII and vitamin K

Question 29

Describe the pathway to thrombin (phase 2)

Answer 29

The prothrombin activator catalyzes transformation of prothrombin to activate enzyme thrombin

Question 30

What are anticoagulants?

Answer 30

Factors that normally dominate in blood to inhibit coagulation

Question 31

How is fibrinogen coverted to fibrin?

Answer 31

With thrombin

Question 32

Why activates thrombin factor XIII?

Answer 32

To form cross-link fibrin and to strengthen and stabilizes the clot