Hemostasis And Related Disorders

Front 1

Primary hemostasis-- step 1

Back 1

1. Transient vasoconstriction of damaged vessel
2. Mediated by reflex neural stimulation and endothelin release from endothelial cells

Front 2

Primary hemostasis-- step 2

Back 2

1. Platelet adhesion to the surface of disrupted vessel
2. vWF binds exposed subendothelial collagen
3. Platelets bind vWF using GPIb

Front 3

Primary hemostasis-- step 3

Back 3

1. Platelet degranulation
2. Adhesion induces shape change in platelets and degranulation with release of multiple mediators
3. ADP is released from platelet dense granules

Front 4

ADP promotes

Back 4

a. Exposure of GPIIb/IIIa receptor on platelets
b. TXA2 is synthesized by platelet cyclooxygenase and released→ promotes platelet aggregation

Front 5

Primary hemostasis-- step 4

Back 5

1. Platelets aggregate at site of injury via GPIIb/IIIa using fibrinogen as a linking molecule→ platelet plug
2. Platelet plug is weak→ stabilized by coagulation cascade

Front 6

Secondary homeostasis

Back 6

i. Coagulation cascade stabilizes weak platelet plug
1. Cascade generates thrombin

Front 7

Thrombin

Back 7

a. Converts fibrinogen in platelet plug to fibrin
b. Fibrin cross-linked yielding a stable platelet-fibrin thrombus

Front 8

Factors of coagulation cascade

Back 8

1. Produced in liver in an inactive state

Front 9

Activation of cascade requires...

Back 9

1. Exposure to an activating substance
2. Tissue thromboplastin activates factor VII (extrinsic)
3. Subendothelial collagen activates factor XII (intrinsic pathway)
4. Phospholipid surface of platelets
5. Calcium (derived from dense granules)

Front 10

Thrombosis

Back 10

a. Pathologic formation of an intravascular blood clot
b. Can occur in artery or vein
c. Most common location is deep veins of the leg below the knee

Front 11

Thrombosis characterized by--

Back 11

i. Attachment to vessel wall
ii. Lines of Zahn
iii. Both help distinguish thrombus from postmortem clot

Front 12

Lines of Zahn

Back 12

1. Alternating layers of platelets/fibrin and RBCs

Front 13

Disruption in normal blood flow

Back 13

i. Stasis and turbulence of blood flow increases risk for thrombosis
ii. Blood flow is normally continuous and laminar
iii. Keeps platelets and factors dispersed and inactivated

Front 14

Increased risk for DVT

Back 14

a. Immobilization
b. Cardiac well dysfunction
c. Aneurysm

Front 15

Endothelial cell damage

Back 15

i. Endothelial damage disrupts the protective function of endothelial cells increasing risk for thrombosis

Front 16

Prevention of thrombosis by sub endothelial cells

Back 16

(one way)
1. Block exposure to subendothelial collagen and underlying tissue factor

Front 17

Produces prostacyclin (PGI2) and NO

Back 17

a. Vasodilation and inhibition of platelet aggregation

Front 18

Secrete heparin-like molecules

Back 18

a. Augment antithrombin III
b. Inactivates thrombin and coagulation factor

Front 19

Secrete tissue plasminogen activator

Back 19

a. tPA
b. Converts plasminogen to plasmin which→
c. Cleaves fibrin and serum fibrinogen
d. Destroys coagulation factors
e. Blocks platelet aggregation

Front 20

Secretes thrombomodulin

Back 20

a. Redirects thrombin to activate protein C
b. Inactivates factors V and VIII

Front 21

Embolism

Back 21

a. Intravascular mass that travels and occludes downstream vessels
b. Symptoms depend on the vessel involved

Front 22

Thromboembolus

Back 22

i. Due to a thrombus that dislodges
ii. Most common type of embolus

Front 23

Atherosclerotic embolus

Back 23

i. Due to an atherosclerotic plaque that dislodges
ii. Characterized by the presence of cholesterol clefts in the embolus

Front 24

Fat embolus

Back 24

i. Associated with bone fractures
ii. Particularly long bones and soft tissue trauma
iii. Develops while fracture is still present or shortly after repair
iv. Characterized by dyspnea and petechiae on skin overlying chest

Front 25

Gas embolus

Back 25

i. Classically seen in decompression sickness
ii. N2 gas precipitates out of blood due to rapid ascent
iii. Present with joint and muscle pain and respiratory symptoms
iv. May also occur during laparoscopic surgery

Front 26

Amniotic fluid embolus

Back 26

i. Enters maternal circulation during labor or delivery
ii. Presents with shortness of breath, neurologic symptoms, and DIC
iii. Characterized by squamous cells and keratin debris from fetal skin in embolus

Front 27

Systemic embolism

Back 27

i. Due to thromboembolus
ii. Most commonly arise in the left heart
iii. Travel down systemic circulation to occlude flow to organs, most commonly the lower extremities

Front 28

Pulmonary emboli

Back 28

i. Usually due to thromboembolus

Front 29

Pulmonary emboli most often clinically silent because....

Back 29

1. Lung has a dual blood supply
2. Embolus is usually small and resolves

Front 30

Pulmonary infarction

Back 30

1. Occurs if large- or medium-sized artery is obstructed in patients with pre-existing cardiopulmonary compromise
2. Only 10% of PEs cause infarction

Front 31

Pulmonary infarction presentation

Back 31

a. Shortness of breath, hemoptysis, pleuritic chest pain, pleural effusion
b. Spiral CT shows a vascular filling defect in lung
c. D-dimer elevated
d. Gross examination reveals a hemorrhagic, wedge-shaped infarct

Front 32

Death from pulmonary infarction

Back 32

a. Occurs with a large saddle embolus that blocks both left and right pulmonary arteries with significant occlusion of a large pulmonary artery
b. Death is due to electromehcanical dissociation

Front 33

Edema

Back 33

a. Abnormal increase in interstitial fluid within tissues
b. Due to increased capillary pressure or diminished colloid osmotic pressure
c. Typically a protein-poor transudate

Front 34

Typically seen in patients suffering from....

Back 34

i. Heart failure
ii. Renal failure
iii. Hepatic failure
iv. Malnutrition

Front 35

Inflammatory edema

Back 35

i. Fluid will be a protein-rich exudate
ii. Result of increased vascular permeability

Front 36

Reduced plasma osmotic pressure

Back 36

i. Occurs when albumin is not synthesized in adequate amounts or is lost from circulation
ii. Levels maintained by kidneys
iii. Leads to net movement of fluid into interstitial tissues
iv. Low renal perfusion
v. Increased renin-angiotensin-aldosterone secretion

Front 37

Low albumin may indicate...

Back 37

1. Nephrotic syndrome
2. Liver disease
3. Protein malnutrition

Front 38

Lymphatic obstruction

Back 38

i. Lymphedema→ typically localized
ii. Can be due to surgery, neoplasms, inflammation, or occur postirradiation

Front 39

Another name for hydroperioneum

Back 39

i. Anasarca

Front 40

Hyperemia

Back 40

a. Active process
i. Arteriolar dilation leads to increased blood flow and engorgement of vessels with oxygenated blood.

Front 41

Congestion

Back 41

a. Passive process
b. Resulting from reduced outflow of blood from a tissue
c. Systemic→ cardiac failure
d. Local→ venous obstruction

Front 42

Congested tissue characteristics

Back 42

i. Cyanosis
ii. Red cell stasis
iii. Deoxygenated hemoglobin

Front 43

Acute pulmonary congestion

Back 43

i. Engorged alveolar capillaries

Front 44

Chronic pulmonary congestion

Back 44

i. Septa are thickened and fibrotic
ii. Alveoli contain numerous hemosiderin-laden macrophages (heart failure cells)

Front 45

Acute hepatic congestion

Back 45

i. Central vein and sinusoids are distended
ii. Centrilobular hepatocytes are ischemic
iii. Periportal hepatocytes develop fatty change

Front 46

Chronic passive hepatic congestion

Back 46

i. Centrilobular regions are grossly red-brown and slightly depressed
ii. Accentuated against surrounding zones of uncongested liver
iii. “Nutmeg liver”

Front 47

Hemorrhage

Back 47

a. Extravasation of blood into the extravascular space
b. Can occur under chronic congestion

Front 48

Hematoma

Back 48

i. Any accumulation of blood with a tissue

Front 49

Petechiae

Back 49

i. 1-2mm hemorrhages on skin, mucous membranes, or serosal surfaces
ii. Associated with increased intravascular pressure

Front 50

Purpura

Back 50

3mm
ii. Can be secondary to trauma, vasculitis, or increased vascular fragility

Front 51

Ecchymoses

Back 51

i. >1-2 cm
ii. Red cells in lesions phagocytized
iii. Hemoglobin is enzymatically converted to bilirubin leading to hemosiderin→accounting for characteristic color changes in a bruise

Front 52

Shock

Back 52

a. Characterized by systemic hypotension
b. Due either to reduced cardiac output or to reduced effective circulating blood volume
c. Leads to impaired tissue perfusion and cellular hypoxia

Front 53

Cardiogenic shock

Back 53

i. Low cardiac output
ii. Due to myocardial pump failure

Front 54

Septic shock

Back 54

i. Results from vasodilation and peripheral pooling of blood
ii. Systemic reaction to bacterial or fungal infection