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OMS II BECOM Exam 1 > homeostasis and clotting - Atchley > Flashcards

homeostasis and clotting - Atchley Flashcards

1
Q

homeostasis

A

vessel spasm –> platelet plug (anchor is vWF**) –> blood coagulation (intrinsic/extrinsic) –> clot retraction –> clot dissolution

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2
Q

vWF**

A

-tethers the platelets to exposed collagen

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3
Q

secretory granules in platelets

A
  • ADP –> promotes GP2b/3a to be expressed on the surface
  • TXA2 –> from arachidonic acid cascade (aspirin irreversibly inactivates COX –> no TXA2)**
  • both ADP and TXA2 activate platelets making them sticky and recruit aggregation of other platelets
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4
Q

vascular spasms

A
  • takes <1 min
  • triggered by trauma, slows platelets down so they can bind
  • vasoconstriction through sympathetic nervous system
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5
Q

platelet plug formation

A

-vWF attaches to exposed collagen allowing platelets to bind through GP1b**

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6
Q

vWF**

A
  • for platelet aggregation and protect of factor 8**

- need to monitor vWF in Hemophilia A with factor 8 deficiency**

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7
Q

how do platelets cross link?

A
  • through fibrinogen by binding to GP2b/3a** complexes

- ADP and TXA2 increase expression of GP2b/3a** –> targets for anti-platelet drugs

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8
Q

secondary hemostasis

A
  • blood coagulation due to fibrin mesh surrounding platelet plug (thrombus)
  • coagulation factors made in liver
  • intrinsic (contact factor path) –> activated by sub endothelial collagen** –> activate factor 12**
  • extrinsic (tissue factor path) –> activated by release of tissue factor (aka tissue thromboplastin)** –> activated factor 7**
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9
Q

other factors

A
  • factor 4 –> Ca2+ (non protein, chelatable)
  • factor 3 –> tissue factor –> starts extrinsic path when cell explodes and activates factor 7**
  • factor 13 –> strengthening factor** (cross links fibrin)
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10
Q

vitamin K dependent factors**

A
  • factor 2,7,9,10** (factor 7 is very sensitive)**
  • protein C and protein S (natural anticoagulants)**
  • protein C more sensitive to vit. K than factor 7**

vit. K required for the synthesis/carboxylation of these factors in liver –> no factors with liver failure

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11
Q

common pathway

A
  • factor 10 down

- converts to thrombin –> takes fibrinogen (soluble) to fibrin (insoluble)

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12
Q

Ca2+ role in coagulation path

A
  • everywhere

- removed to prevent activation in order to test pathways** (reversible)

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13
Q

clot retraction (after 20-60 min)

A

-squeezes serum from clot and joins separated vessel walls

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14
Q

clot dissolution (fibrinolysis)

A
  • hep reestablish blood flow
  • tPA –> converts plasminogen to plasmin to break clots**
  • plasmin digest fibrin and certain clotting factors**
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15
Q

lab tests to measure coagulation***

A
  1. fibrin split products (D-dimer)

2. fibrin degradation products (FDP)

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16
Q

factors preventing clot formation

A 
1. from healthy endothelial cells: 
Prostacyclin &amp; nitric oxide: Platelet plug inhibitors
Heparan sulfate: Activates antithrombin
Thrombomodulin: binds to thrombin
Tissue factor pathway inhibitor
  1. circulating anticoagulants
    - antithrombin (enhanced by heparin) neutralized thrombin and inhibits factor 10a**
    - protein C (enhanced by protein S) inactivates factors 5a and 8a***
    - plasmin degrades fibrin
17
Q

what is most effect in vit. K deficiency?**

A
  • factor 7 and protein C** (sensitive and have short half-lives)
  • extrinsic path more prone to damage if Vit. K deficient**
18
Q

which path is most sensitive to warfarin/coumadin?**

A

-extrinsic pathway**

19
Q

PT (prothrombin time) and PTT (partial thromboplastin time)**

A
  • PT –> measures the extrinsic pathway** (better test for Coumadin)**
  • PTT –> measures the intrinsic pathway** (better test for Heparin)**
  • measured in seconds needed to form clots
20
Q

INR

A
  • system for standardizing PT
  • used to monitor warfarin/coumadin therapy
  • DVT (2-3)
  • mechanical heart valve (2.5-3.5)
21
Q

coagulation disorders - impaired synthesis of coagulation factors

A
  • liver disease: no fibrinogen, prothrombin, or coagulation factors
  • vit. K (produced by gut bacteria) deficiency
22
Q

von willebrand disease (vWF)**

A
  • # 1 genetic coagulation disorder disease

- mild cutaneous, mucosal bleeds**

23
Q

hemophilia A

A
  • most common SEVERE bleeding disorder**
  • serious deep joint/muscle bleeds**
  • X-linked in factor 8 deficiency**
  • mom will be a carrier (mostly in boys)
  • test with PTT**
24
Q

hemophilia B

A
  • 2nd most common SEVERE bleeding disorder
  • serious deep joint/muscle bleeds**
  • X-linked in factor 9 deficiency** (Christmas factor)
  • mom will be a carrier (mostly in boys)
  • test with PTT**
25
Q

disseminated intravascular coagulation (DIC)

A
  • systemic coagulation and bleeding disorder**
  • uncontrolled activation of coagulation cascade –> uses up all the factors/platelets –> sever hemorrhage and organ failure
  • PT/PTT are increased due to factor consumption
  • low platelets and fibrinogen (used up)

coagulation factors normal in TTP*** (don’t mess with coagulation cascade)

26
Q

TXA2

A

-formation prevented by low dose aspirin** due to irreversible inhibition of COX

27
Q

low dose aspirin**

A
  • targets COX enzyme –> inhibits TXA2 formation –> no platelet aggregation**
  • reduces inflammation, fever, pain
  • stop 2-3 days before surgery so platelets can build up

endothelial cells can replace TXA2 (have their own COX), but platelets can’t bc they don’t have a nucleus

28
Q

COX pathway

A
  • form TXA2 (thrombotic) and PGI2 (antithrombotic)
  • also form PGD2,E2,F2
  • PGE2 is fever modulator**
29
Q

phospholipase A2/PLA2

A

inhibited by steroids - blocks everything downstream

30
Q

LOX pathway

A

-important for asthma**

31
Q

heparin***

A
  • activates antithrombin (factor 2a)**
  • inhibits factor 10a just as much/if not more than factor 2a**
  • also inhibits factors 12,11,10,9,2
  • monitor with PTT**
  • infused
32
Q

warfarin/coumadin

A
  • depletes vitamin K by depleting epoxide reductase, which recycles vit. K after it carboxylates factors 2,7,9,10
  • inhibits synthesis of vit. K dependent factors
  • monitor with PT/INR**
  • inhibits vit. K absorption in GI
  • taken orally

OMS II BECOM Exam 1 (30 decks)

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