Summary's Chapter 4: Hemodynamic Disorders, Thromboembolism, and Shock Flashcards
What is edema? (for dutchies: oedeem)
Edema results from the movement of fluid from the vasculature into the interstitial spaces; the fluid may be protein poor (transudate) or protein rich (exudate).
What may edema be caused by?
- Increased hydrostatic pressure
- Increased vascular permeability
- Decreased colloid osmotic pressure resulting from reduced plasma albumin
- Lymphatic obstruction
- Sodium retention
Decreased colloid osmotic pressure can be because of 2 causes. What are these?
- Decreased synthesis
* Increased loss
What is an example of increased hydrostatic pressure that causes edema?
Heart failure
What is an example of increased vascular permeability that causes edema?
Inflammation
What is an example of decreased synthesis and what is an example of increased loss causing a decreased colloid osmotic pressure, resulting from reduced plasma albumin?
• Decreased synthesis (e.g., liver disease, protein
malnutrition)
• Increased loss (e.g., nephrotic syndrome)
What is an example of lymphatic obstruction causing edema?
Inflammation or neoplasia
What is an example of sodium retention causing edema?
Renal failure
Fill in: Endothelial injury exposes the underlying basement membrane ECM (=extracellular matrix); platelets adhere to the ECM primarily through the binding of platelet … receptors to …
GpIb, VWF (von willebrand factor) (respectively)
Fill in: Adhesion leads to …, an event associated with secretion of platelet granule contents
platelet activation,
Which platelet granule contents are secreted during platelet activation?
Calcium (a cofactor for several coagulation proteins) and ADP (a mediator of further platelet activation); dramatic changes in shape and membrane composition; and activation of GpIIb/IIIa receptors.
With what molecule can GpIIb/IIIa receptors on activated platelets bind? How do they do this?
Bridging crosslinks with fibrinogen, leading to platelet aggregation.
Fill in: Concomitant activation of thrombin promotes … deposition, cementing the platelet plug in place.
fibrin
True/false: Coagulation occurs via the sequential enzymatic conversion of a cascade of circulating and locally synthesized proteins.
True
Fill in: … elaborated at sites of injury is the most important initiator of the coagulation cascade in vivo.
Tissue factor
Fill in: At the final stage of coagulation, thrombin converts fibrinogen into … that contributes to formation of the definitive hemostatic plug.
insoluble fibrin
Coagulation normally is restricted to sites of vascular injury. By what pathways/mechanisms is that (4 answers)
• limiting enzymatic activation to phospholipid surfaces provided by activated platelets or endothelium,
• circulating inhibitors of coagulation factors, such as anti-thrombin III, whose activity is augmented by heparin-like molecules expressed on endothelial cells
• expression of thrombomodulin on normal endothelial cells,
which bind thrombin and convert it into an anti-coagulant,
• activation of fibrinolytic pathways (e.g., by association of
tissue plasminogen activator with fibrin)
Thrombus development is usually related to one or more components of Virchow’s triad. What are these components?
• endothelial injury (e.g., by toxins, hypertension, inflammation, or metabolic products) • abnormal blood flow, stasis, or turbulence (e.g., resulting from aneurysms, atherosclerotic plaque) • hypercoagulability: either primary (e.g., factor V Leiden, increased prothrombin synthesis, anti-thrombin III deficiency) or secondary (e.g., bed rest, tissue damage, malignancy)
True/false: Thrombi may propagate, resolve, become organized, or embolize.
True
Thrombosis causes tissue injury by …
local vascular occlusion or
by distal embolization.
What is an embolus?
An embolus is a solid, liquid, or gaseous mass carried by the blood to a site distant from its origin; most are dislodged thrombi.
Pulmonary emboli derive primarily from ….
lower-extremity deep vein thrombi
The effects of pulmonary emboly depend mainly on ….
the size of the embolus and the location in which it lodges
What are possible consequences because of a pulmonary emboli?
Consequences may include right-sided heart failure, pulmonary hemorrhage, pulmonary infarction, or sudden death.
Where do systemic emboli derive from?
Cardiac mural or valvular thrombi, aortic aneurysms, or atherosclerotic plaques
Does an embolus, per definition, cause tissue infarction?
No, it depends on the site of embolization and the presence/absence of collateral circulation
How can fat embolism occur?
After crushing injuries to the bone
What are the symptoms of fat embolism?
Pulmonary insufficiency and neurological damage
Amniotic fluid embolism may follow childbirth and can give rise to ….
fatal pulmonary and cerebral manifestations.
Air embolism can occur upon rapid decompression, most commonly in divers; it results from …
sudden bubbling of nitrogen dissolved in blood at higher pressures.
What are infarcts and what are they caused by?
Infarcts are areas of ischemic necrosis most commonly caused by arterial occlusion (typically resulting from thrombosis or embolization); venous outflow obstruction is a less frequent cause.
What colour are infarcts caused by venous occlusion or occurring in spongy tissues typically?
Red (because of hemorrhage)
What colour are infarcts caused by arterial occlusion in compact tissues typically?
White (pale)
Whether or not vascular occlusion causes tissue infarction is influenced by ….
collateral blood supplies, the rate at which an obstruction develops, intrinsic tissue susceptibility to ischemic injury, and blood oxygenation.
What is shock?
A state of systemic tissue hypoperfusion resulting from reduced cardiac output and/or reduced effective circulating blood volume.
What are the major types of shock?
cardiogenic (e.g., myocardial infarction), hypovolemic (e.g., blood loss), and septic (e.g., infections).
True/false: shock always causes injury
False, but shock of any form can lead to hypoxic tissue injury if not corrected.
What is septic shock caused by?
by the host response to bacterial or fungal infections;
What is septic shock characterized by?
It is characterized by endothelial cell activation, vasodilation, edema, disseminated intravascular coagulation, and metabolic derangements.
