Hemostasis

Question 1

Four steps of hemostasis

Answer 1

1. Vasoconstriction
2. Primary hemostasis: Formation of platelet plug
3. Secondary hemostasis: Formation of blood clot
4. Fibrous organization

Question 2

Petechiae

Answer 2

Small red/purple/brown ‘pinpoint’ spots that appear due to bleeding into the skin.

Question 3

Purpura

Answer 3

Petechiae that is 3 - 10 mm, do not blanch upon applying pressure

Question 4

Vasculitis

Answer 4

Inflammation of the blood vessels–can occur due to infection, medicine, or disease

Question 5

Hematoma

Answer 5

Collection of blood (usually clotted) outside of the damaged vessel, into surrounding tissue

Question 6

Ecchymosis

Answer 6

Superficial bleeding under the skin/mucous membrane–a bruise

Question 7

Thrombosis

Answer 7

Formation/presence of a blood clot inside a blood vessel

Question 8

Embolism

Answer 8

obstruction in a blood vessel (blood clot, fat globule, gas bubble, etc)

Question 9

Thromboembolism

Answer 9

obstruction of a blood vessel by a blood clot dislodged from another site in the circulation.

Question 10

Infarction

Answer 10

Necrosis of tissue from lack of oxygen due to obstruction of the tissue’s blood supply

Question 11

Primary hemostasis: platelet plug formation

Answer 11

1. Adhesion (vWF, collagen receptors)

2. Aggregation (fibrinogen)

Question 12

Secondary hemostasis: blood clot formation

Answer 12

Extrinsic + intrinsic -> activate Factor X
Prothrombin -> thrombin
Fibrinogen -> fibrin

Question 13

Fibrinolytic system

Answer 13

Plasminogen -> plasmin (breaks up clot)

Thrombin (triggers thrombin-activatable fibrinolysis inhibitor, which also cleaves the fibrin clot)

Question 14

Vitamin K in clotting

Answer 14

Vitamin K is responsible for the formation of 4 important clotting factors in the Extrinsic, Intrinsic, and Common clotting pathways:
Extrinsic- Factor VII
Intrinsic- Factor IX
Common- Factor II (prothrombin -> thrombin),
Factor X (where they meet up)

Question 15

Hemophilia

Answer 15

chromosomal disorder where blood can’t clot b/c lack Factor VIII from mutation of X chromosome. Very few are cases are from Factor IX deficiency

Question 16

DVT

Answer 16

blood clot (thrombus) usually in leg, can cause swelling. Occur when don’t move (accident, airplane, bedrest), dangerous= can lead to pulmonary embolism

Question 17

Thrombocytopenia

Answer 17

low platelet count, easily bleed, skin has purple blotches

Question 18

PE

Answer 18

blockage of pulmonary arteries from a traveling blood clot (thrombus); emergency!

Question 19

disseminated intravascular coagulation

Answer 19

usually a complication from another disease; cascade of unnecessary formation of blood clots in small blood vessels, compromise blood flow and lead to organ damage. Normal clotting disrupted and severe bleeding can occur

Question 20

Bleeding time

Answer 20

crude test, making small cut on forearm. Measures platelet function. 2-9 minutes is normal. Not specific nor sensitive, and influenced by external factors like medications & thrombocythemia

Question 21

Platelet count

Answer 21

number/concentration of platelets in a blood sample. 150k-450k/microliter is normal. Clinically notable when falls below 100k. Below 20k - mild spontaneous bleeding. Higher platelet count = great coagulation status = less bleeding time

Question 22

Partial thromboplastin time (pTT)

Answer 22

screens for deficiencies and inhibitors of the intrinsic pathway (factors 8, 9, 11, 12) and factors in the final common pathway (factors 2, 5, 10). (Per our lecture, we can think of PTT & aPTT as the same)

Question 23

Prothrombin time (PT

Answer 23

time it takes for clot to form after calcium and thromboplastin (Ca activator) are added. Also, assesses extrinsic (factor 7) and common pathways (2, 5, 7, 10)

Question 24

D-dimer

Answer 24

a neoantigen formed & released into the blood when blood clots (fibrin) degrades. less than 0.5 mcg/mL or less than 200 ng/mL is normal. Quick, easy test used to determine if abnormal clotting is present; diagnoses/rules out thrombosis in patients. Does not specify location of abnormal clotting → do further testing

Question 25

Platelet function test

Answer 25

measures ability for platelets to aggregate. Gold standard: LTA (light transmittance aggregometry) which measures light transmittance through a sample of platelets in suspension. More light is transmitted when a platelet-aggregated agonist is added to the sample. Very expensive