4-Hemodynamics, Thromboembolitics, and Shock Flashcards
What is edema?
when the movement of water into tissues exceeds lymphatic drainage, fluid accumulates
What causes edema?
results when either increased capillary pressure or diminished colloid pressure causes an increased interstitial fluid
What prefix do we use to tell that there is edema in various cavities?
Hydro- (hydrothorax, hydropericardium, and hydroperitoneum (ascites))
What is anasarca?
severe and generalized edema with widespread subcutaneous tissue swelling
Why does increased hydrostatic pressure cause edema?
when veins are blocked or arterioles dilate, the increased hydrostatic pressure in the arteries squeezes more fluid into the interstitial fluid, causing edema
Why does reduced plasma osmotic pressure cause edema?
when there is less proteins in the blood, the osmotic pressure will be smaller than the osmolarity in the interstitial fluid, drawing water into the interstitial fluid causing edema
Why does blocked lymphatics cause edema?
If the lymphatics are blocked, they can’t drain the interstitial fluid, causing edema
Edema from increased hydrostatic pressure or reduced protein results in what type of fluid to leak into tissues?
Transudate
What medical conditions cause transudate in edema?
This is seen in heart failure, renal failure, hepatic failure, and certain forms of malnutrition.
Inflammatory edema is causes what type of fluid to leak into the interstitum
exudate
What is hyperemia?
it’s an active process in which arteriolar dilation leads to increased blood flow
What is the morphology of hyperemia?
Affected tissues turn red (erythema) because of all oxygenated blood accumulation
What is congestion?
it’s a passive process from reduced outflow of the blood from a tissue. It can be systemic, from like cardiac failure, or local like in a vein obstruction
What is the morphology of congestion?
Tissues turn cyanotic due to RBC stasis and accumulation of deoxygenated blood
The accumulation of what specific cells present in congestion?
hemosiderin-laden macrophage clusters
What is a hemorrhage?
extravasation of blood into the extravascular space. This may be external or contained within a tissue
What is a hematoma?
any accumulation of blood within a tissue.
What are petechiae?
1-2mm hemorrhages (“pindots”) on the skin, mucous membranes or serosal surfaces
What causes petechiae?
Often from increased intravascular pressure or low/defective platelets
What are the size of purpura?
larger (>3mm) hemorrhages
What causes purpura?
from trauma, vasculitis, or vascular fragility (amyloidosis).
What are ecchymoses?
1-2cm subcutaneous hematomas (bruises)
What prefix do we use to show where blood is accumulating?
Hemo- (hemothorax, hemopericardium, hemoperitoneum, or hemoarthosis)
What is normal hemostatis?
this is the first stage of wound healing, when the rapid formation of a hemostatic clot is formed
What is the first thing that happens in normal hemostasis, after injury?
local secretion of endothelin causes arteriolar vasoconstriction
What occurs during primary hemostasis?
platelet activation and aggregation
Where is the tissue factor/factor III/thromboplastin released from?
endothelial cells
What does the tissue factor do?
makes thrombin
What does thrombin do?
Cleaves fibrinogen to fibrin
What does fibrin do?
Gets poured onto the platelets to form the platelet plug (this is secondary hemostasis)
What is the main counter-regulatory mediator that down-regulates the clotting cascade?
tissue plasminogen activator (t-PA)
What is the most important coagulation factor?
Thrombin
What is the intrinsic coagulation pathway?
aka “contact activation pathway,” involved with many factors that are activated when polyanionic surfaces are encountered
What is the extrinsic coagulation pathway?
aka “tissue factor pathway,” involved solely with tissue factor (thromboplastin) getting activated by factor VII. This occurs when tissues are damaged
Which coagulation pathway is Hageman factor (XII) involved in?
intrinsic pathway
Which pathway does the prothrombin time (PT) measure?
Extrinsic pathway
Which factors does the PT measure?
factors II, V, VII and X
How do we activate the PT test?
using exogenous Ca++
<p>
| What factors does the PTT measure?</p>
<p>
| factors II, V, VIII-XII</p>