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PHGY 209 > Blood V > Flashcards

Blood V Flashcards

1
Q

Loss of blood is called […]

A

Hemorrhage

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2
Q

What are the two type of hemorrhage?

A

External and internal

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3
Q

Internal bleeding is called […]

A

Hematoma

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4
Q

The arrest of bleeding is called […]

A

Hemostasis

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5
Q

Describe the various components of the body’s hemostasis response.

A

It consists of a vascular response, platelet response, and clot formation. Vascular response and platelet response are considered primary hemostasis, while clot formation is considered secondary hemostasis.

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6
Q

What are the four steps of injury healing?

A
  1. Vascular injury
  2. Vasoconstriction (vascular response)
  3. Platelet plug formation
  4. Blood clot formation
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7
Q

Describe what happens during vasoconstriction.

A

The nervous reflex makes opposed endothelial cells stick together. There is then a myogenic response, where smooth muscle cells in the vessel wall respond to injury by contracting. There are also chemical vasoconstrictors.

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8
Q

The platelet plug is also called […]

A

The white thrombus

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9
Q

The blood clot is also called […]

A

The red thrombus

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10
Q

How big are platelets?

A

2-4 um diameter

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11
Q

Describe the structure and organelles of platelet cells

A

They also don’t have a nucleus, but it does have many granules, including factors for vasoconstriction, platelet aggregation, clotting, and growth; filaments; microtubules; mitochondria, and smooth endoplasmic reticulum.

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12
Q

What is the lifespan of platelets?

A

7-10 days

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13
Q

Where does the production of platelets take place?

A

In the axial skeleton in adults- identical to all other blood cells.

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14
Q

Platelet production is stimulated in the […] by […], which is produced in the […]

A

Committed stem cell, thrombopoietin, liver

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15
Q

Describe the steps involved in platelet production.

A

They also start with a pluripotential stem cell, which becomes a committed stem cell (myeloid cell) on which thrombopoietin acts. It then grows into a megakaryocyte, a large cell with a nucleus. The nucleus divides and the megakaryote eventually leaves the bone marrow and goes into the blood stream, breaking off into tiny pieces.

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16
Q

What are the 4 steps in platelet plug formation?

A
  1. Adhesion
  2. Activation and release of cytokines
  3. Aggregation
  4. Consolidation
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17
Q

The endothelial cells in the blood vessel produce […] and […]. What do they do?

A

Prostacyclin, nitric oxide. They cause the dilation of the blood vessel and push away cells that get close to the wall.

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18
Q

Describe the adhesion step of platelet plug formation.

A

When there is damage to the vessel wall and collagen is exposed, platelets will stick there. A plasma protein called the von Willebrand factor promotes the adhesion of platelets to the endothelium.

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19
Q

Describe the activation, aggregation, and consolidation steps of platelet plug formation.

A

Once the platelets adhere to the endothelium, they are activated and release cytokines, Thromboxane A2, serotonin, ADP, and Platelet Factor 3, which further promote the aggregation and consolidation of platelets to make the plug firmer.

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20
Q

What are the functions of Thromboxane A2?

A

It promotes the aggregation and consolidation of platelets in the platelet plug and is a vasoconstrictor.

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21
Q

What is the function of serotonin?

A

It is a vasoconstrictor.

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22
Q

What is the function of PF3?

A

It participates in coagulation.

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23
Q

What is the function of ADP?

A

It promotes the aggregation of platelets.

24
Q

The key proteins involved in the adherence and aggregation of platelets to form the platelet plug are […]

A

Collagen and the von Willebrand factor (initially), thromboxane A2 and PF3 (after).

25
Q

What are the 5 functions of platelets?

A
  1. Release vasoconstricting agents
  2. Form platelet plug
  3. Release clotting factors
  4. Participate in clot retraction
  5. Promote maintenance of endothelial integrity
26
Q

Bleeding under the skin due to the breakup of capillaries is called […]

A

Petechiae

27
Q

Name two possible causes of prolonged bleeding.

A
  1. Failure of blood vessel to constrict
  2. Platelet deficiencies, either numerical or functional.
28
Q

Numerical platelet deficiencies that result in prolonged bleeding are called […]. This occurs at a concentration of less than […] platelets.

A

Thrombocytopenia. <75,000 platelets/uL

29
Q

What are the types of functional platelet deficiencies that can lead to prolonged bleeding?

A

Congenital or acquired by drugs, toxins, and antibodies.

30
Q

Give an example of a drug that inhibits clotting and how.

A

Aspirin - it inhibits synthesis and release of Thromboxane A2, which is key in primary hemostasis by encouraging aggregation of platelets and promoting vasoconstriction. It essentially inhibits platelet adhesion.

31
Q

Another word for a blood clot is a […]

A

Thrombus

32
Q

Name all the blood cell types that are involved in clotting.

A

Just platelets. RBCs and WBCs are not involved.

33
Q

What is the definition of clotting?

A

It is initiated by injury to the blood vessel wall, resulting in sequential activation and interaction of a group of plasma proteins or clotting factors (some acting as enzymes, others acting as co-factors), in the presence of Ca2+ and some phospholipid agents.

34
Q

Describe stage 3 of clotting.

A

Fibrinogen is secreted by the liver and converted into fibrin, an insoluble protein, by a protein called thrombin. It get incorporated into the clot such that it consists of cross-linked fibrin.

35
Q

Describe stage 2 of clotting.

A

Prothrombin is secreted from the liver, which in the presence of Ca2+ and the enzyme prothrombinase, will give rise to Thrombin. The Thrombin activates plasma factor XIII, which becomes XIIIa that forms a fibrous network that contributes to the cross-linked fibrin clot in stage 3.

36
Q

What are the two ways in which prothrombinase can be produced?

A

The intrinsic pathway, which uses elements already present in the bloodstream, or the extrinsic pathway, which uses substances from the injured cells near the injury.

37
Q

What happens in the first stage of clotting?

A

Prothrombinase is produced either via the intrinsic or extrinsic pathway.

38
Q

Describe the intrinsic pathway of prothrombinase production.

A

Caused by damage to blood vessel - exposed collagen causes conversion of 12 -> 12a. This then causes a series of plasma factor reactions ending with 10 -> 10a. 10a + Va + platelet factor + Ca2+ -> prothrombinase

39
Q

Describe the extrinsic pathway of prothrombinase production.

A

Caused by tissue damage - tissue factors phospholipid and prot cause the conversion of VII -> VIIa. This then triggers the conversion of 10 -> 10a. 10a + Va + platelet factor + Ca2+ -> prothrombinase

40
Q

Explain the relationship between the intrinsic and extrinsic pathway of prothrombin production.

A

The extrinsic pathway is very rapid, only about 15-20 seconds, but only produces a small amount of prothrombinase to get the clot started. Once a small amount of thrombin has been produced, it will create a positive feedback on the intrinsic production of thrombin, leading to more clotting.

41
Q

The intrinsic pathway takes […], while the extrinsic pathway takes […]

A

3-6 minutes, 15-20 seconds

42
Q

The small amounts of thrombin generated by the […] are sufficient to trigger a […] on the […] to generate […] quantities of thrombin.

A

Extrinsic scheme, positive feedback, intrinsic scheme, larger

43
Q

Clotting is kept in check by […] and […]

A

Inhibitors (of platelet adhesion) and anticoagulants (chemicals that block one or more reactions of the coagulation scheme)

44
Q

What are the 3 factors involved in coagulation? Which ones tend to be lacking?

A

Ca2+, phospholipids, and protein plasma factors. There is typically enough Ca2+ and phospholipid, but protein plasma factors can be lacking.

45
Q

What are two types of clotting factor deficiencies?

A

Congenital and acquired.

46
Q

Explain what congenital clotting factor deficiencies are and give an example.

A

They are typically hereditary deficiencies of (usually) a single factor. For example, people with hemophilia are deficient in factor VIII, so they struggle to clot.

47
Q

Explain what acquired clotting factor deficiencies are and give an example.

A

It is usually a multifactor deficiency. For example, if one develops liver disease and also has a vitamin K deficiency (which is a cofactor in the synthesis of prothrombin, VII, IX, X)

48
Q

What is clot retraction? What does it result in?

A

Once a blood clot has set in, there is tendency for it to shrink. This leaves behind serum, which is plasma without fibrinogen and the other clotting factors.

49
Q

Clot retraction depends on […], which is released by […]

A

Thrombosthenin, platelets.

50
Q

The process of blood clot destruction is called […]

A

Fibrinolysis (clot lysis)

51
Q

Fibrinolysis is driven by the enzyme […]

A

Plasmin

52
Q

Describe the process of fibrinolysis.

A

The platelet plug and clot are destroyed by plasmin, which breaks up the fibrin network into fibrin fragments that get carried away by blood flow. Plasmin is dervied from plasminogen, which must be activated by a plasminogen activator. The plasminogen activator can be released by extrinsic proactivators (e.g. tissue factors) or intrinsic proactivators (e.g. Factor XIIa) and endothelial cell factors.

53
Q

Fibrinolysis is also called […]

A

Thrombolysis

54
Q

Give an example of a medication that inhibits platelet adhesion.

A

Aspirin

55
Q

Give two examples of medications that are anticoagulants and explain how they work.

A

Coumadin - blocks synthesis of functional prothrombin, VII, IX, X
Heparin - inhibition of thrombin activation and action

56
Q

What is a thrombolytic drug?

A

It is a drug that promotes clot lysis.

57
Q

Give 2 examples of thrombolytic drugs.

A

Tissue plasminogen activator t-PA
Streptokinase

PHGY 209 (33 decks)

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