Chapter 17 - Part 2 Flashcards by kelly raper

Name the 3 steps for stoppage of bleeding

vascular spasm
platelet plug formation
coagulation (blood clotting)

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What is a vascular spasm?

vasoconstriction of damaged blood vessel

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What are the 3 triggers of vascular spasm?

direct injury
chemicals released by endothelial cells and platelets
pain reflexes

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Describe the platelet plug formation at site of blood vessel injury…

platelets contact exposed collagen fibers
become sticky
degranulate - release chemical messengers
causes more platelets to stick and release their contents
plug forms within one minute

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What is a set of reactions in which blood is transformed from a liquid to a gel called?

coagulation

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What does coagulation reinforce the platelet plug with?

fibrin threads

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Coagulation is a multistep process…how many substances and enzymes does it require?

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What are procoagulants?

inactive plasma clotting proteins

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What do antiproagulants do?

prevent clotting

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What are the 3 phases of coagulation?

prothrombin activator is formed (intrinsic & extrinsic pathways)
prothrombin is converted into trhombin
thrombin catalyzes the joining of fibrinogen to form a fibrin mesh

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Name the two pathways to prothrombin activator.

intrinsic pathway

2. extrinsic pathway

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What does the instrinsic pathway use? and what is it triggered by?

uses factors present within the blood

triggered by negatively charged surfaces

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What does the extrinsic pathway bypass? and what is it triggered by?

bypasses several steps of intrinsic pathway, so is faster

triggered by exposure to tissue factor or factor III

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What does factor X complexes involve in order to form prothrombin activator?

Ca2
PF3
factor V

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What is the result of phase 1 in hemostasis?

prothrombin activator is formed

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What is the result of phase 2 in hemostasis?

prothrombin activator catalyzes the transformation from prothrombin to thrombin

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What is the result of phase 3 in hemostasis?

blood clot forms

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Describe the pathway of phase 3 that results in blood clot.

thrombin ->
fibrinogen -> fibrin ->
forms a mesh; traps blood cells ->
blood clot

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What speeds up the healing process?

clot retraction and repair of tissue

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Describe the 5 steps of clot retraction and repair of tissue.

actin and myosin in platelets contract within 30-60 minutes
platelets pull on the fibrin strands, squeezing serum from the clot
edges of wound pull together
PGDF stimulates rebuilding of vessel wall
VEGF stimulates regrowth of endothelium lining the vessel

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What is the breakdown of the scab called?

fibrinolysis

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How long does it take to happen after clotting?

within 2 days

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What is plasminogen in the clot coverted to?

plasmin by tissue plasminogen activator (tpa), factor XII and thrombin

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What is plasmin?

fibrin-digesting enzyme

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What does plasmin do?

breaks fibrin down to fragments and eventually to amino acids

What are the two mechanisms preventing clots from becoming too large?

1. swift removal and dilution of clotting factors | 2. inhibition of activated clotting factors

What are the two factors preventing undesirable clotting?

1. smooth endothelial lining of blood vessels | 2. antithrombic substances nitric oxide and prostacyclin secreted by endothelial cells.

What type of disorder has undesireable clot formation?

thromboembolytic disorder

Name two thromboembolytic disorders and describe.

1. thrombus - clot that develops and persists in an unbroken blood vessel 2. embolus - a thrombus freely floating in the blood stream

What prevents thromboembolytic disorders and how?

1. aspirin - prevents platelets from sticking together 2. heparin - inhibits thrombin formation 3. warfarin - inhibits clotting

What is a disorder that leads to widespread clotting through intact vessels?

disseminated intravascular coagulation

Describe disseminated intravascular coagulation.

severe bleeding occurs because residual blood is unable to clot

When can disseminated intravascular coagulation occur?

during pregnancy or a result of an incompatible blood transfusion

What bleeding disorder creates a deficient number of circulating platelets?

thrombocytopenia

What causes thrombocytopenia?

a suppression or destruction of bone marrow

What disorder happens as a result of the inability to synthesize procoagulants?

impaired liver function

What causes impaired liver function?

vitamin K deficiency, hepatitis, and cirrhosis

What types of disorders include several similar hereditary bleeding disorders?

hemophilias

What is the most common type of hemophilia? and why? is it most common in males or females?

hemophilia A due to a deficiency of factor VIII most common in males

What are the symptoms of hemophilia?

prolonged bleeding, especially into joint cavities

When are whole blood transfusions used?

when blood loss is substantial or when treating thrombocytopenia

In a transfusion packed red cells (plasma removed) are used to restore what?

oxygen-carrying capacity

Humans have different blood types based on what?

specific antigens on RBC membranes

What could happen if a blood transfusion was incompatible?

death

What is agglutination?

sticking together of red blood cells

What are the promoters of agglutination called?

agglutinogens

How many glycoprotein antigens do RBC membranes bear?

What is a humans blood type based on?

specific antigens on RBC membranes

Presence or absence of each antigen is used to classify blood cells into different groups. What are the two groups of blood?

ABO | Rh

Name the the 4 ABO blood groups?

A B AB O

What are the ABO blood groups based on?

the presence or absence of agglutinogens (A or B) on the surface of red blood cells

What are anti-A or anti-B antibodies also called?

aggluntinins

When do anti-A or anti-B form in the blood?

at 2 months of age

How many Rh agglutinogens are there?

Which aggluntinogen causes strong reactions?

agglutinogen D

What does Rh+ indicate vs. Rh-?

Rh+ indicates presence of agglutinogen D | Rh- indicates absence of agglutinogen D

Anti-Rh antibodies are not automatically formed in Rh- individuals. When are they formed?

When a Rh- recipient receives Rh+ blood

What will happen if an Rh- individual receives Rh+ blood for a second time?

a typical transfusion reaction

What is the hemolytic disease of a newborn called?

erythorblastosis fetalis

Describe the 3 things that happen in a transfusion reaction

1. donor's cells are attacked by recipients plasma agglutinins 2. they aggluinate and clog small vessels 3. they rupture and release free hemoglobin into the bloodstream

What two things can a transfusion reaction result in.

1. diminished oxygen-carrying capacity | 2. hemoglobin in kidney tubules and renal failure

What is an agglutinogen?

antigen on RBC (glycoproteins)

What is an agglutinin?

antibodies in plasma (globulins)