Exam 1: DIsorders of blood flow Flashcards
edema
accumulation of fluid in the interstitial tissue spaces of thebody or body cavities
why does edema occur
because there is a loss of homeostatic mechanisms that control the normal fluid volumes of the body
what are the 4 causes of edema
increased microvascular permeability
increased intravascular hydrostatic pressure
decreased intravascular osmotic pressure
decreased lymphatic drainage
what is an example of increased microvascular permeability
generalized or local inflammation due o infectious agents
this is mediated by
release of histamine, bradykinins, leukotrienes, IL-1, TNF, y-interferon
what is an example of increased intravascular hydrostatic pressure
cardiovascular disease or failure; congestion or hyperemia in tissue
what are examples of intravascular osmotic pressure
hepatic failure with acquired or congenital porto-systemic shunt with decreased albumin production; loss of albumin in kidney or GI tract (PLN, PLE)
What is an example of decreased lymphatic drainage
neoplasia, fibrosis or inflmmation that is compressing/obstructing lymphatic vessels; lymphangiectasia in GI tract
what does edema look like morphologically
clear to slightly yellow fluid (mostly water)
“doughy” consistency
leaves a delayed impression (pitting edema)
tissues will be wet or shiny and thickened on necropsy
does edema contain small or large amounts of protein
small; but can be more protein rich in some conditions
where does edema tend to collect
on more ventral regions of body
when edema is present is there any loss of function of the tissue
when severe it can cause partial or complete loss of function and can be life threatening
where can edema be life threatening
CNS edema, pulmonary edema, hydropericardium
edema is recognized how microscopically in H&E?
amorphous, pale eosinophlic material within tissue spaces (dont confuse with fibrin deposition
hydropericardium
watery fluid accumulation within pericardial sac (can be secondary to edema)
hydrothorax
watery fluid accumulation within the thoracic cavity (can be secondary to edema)
hydroperitoneum
one form of ascites that consists of watery fluid accumulation within the abdominal cavity (can be secondary to edema)
hyepremia
active engorgement of small arterioles and capillaries with blood
physiologic hyperemia
hyperthermia, post-prandial to intestines
pathologic hyperemia
increased blood flow secondary to inflammation
what is the morphologic appearance of hyperemia
tissues are reddened and warm to touch
what does hyperemia look like histologically
arterioles and capillaries engorged with blood; RBC in the lumen of the vessels
what types of hyperemia can a pt have
acute/chronic
focal/regionally localized
IMPOSSIBLE TO BE GENERALIZED
congestion
engorgement of small venules and capillaries when venous blood flow is diminished or obstructed (secondary to many pathologic processes)
acute passive congestion
occurs after processes such as acute heart failure, post euthanasia, post barbiturate administration
chronic passive congestion
often secondary to neoplasia (obstructive venous flow) marked inflammation organ displacement (volvulus, torsion) marked fibrosis chronic R side heart failure chronic left side heart failure
what is the morphologic appearance of congestion
tissues are enlarged, heavier, and darker red due to increased blood volume
liver has a nutmeg appearance (mottled red and light yellow appearance diffuse)
what is the microscopic appearance of congestion
increased amount of eryhtrocytes within the lumen of small capillaries and venules (only small amounts of RBC in interstitium due to diapedesis effect or tissue processing artifact)
shock is also known as
cardiovascular collapse
what is shock
a circulatory dysregulation that is associated with loss of circulating blood volume, reduced cardiac output and/or alteration of peripheral vascular resistance
causes of shock are numerous but often secondary to
severe hemorrhage, massive burns, massive tissue trauma, endotoxemia, or severe water loss secondary to diarrhea/vomiting
what is the primary consequence to shock
hypotension and subsequent impaired tissue perfusion and cellular hypoxia leading to anaerobic metabolism, cellular degeneration and death
what are the types of shock
cardiogenic shock
hypovolemic shock
blood maldistribution shock
cardiogenic shock
when heart fails and cant pump blood to tissues
hypovolemic shock
when there is reduced circulating volume of blood/water in the vascular that occurs due to loss of fluids secondary to seere diarrhea, vomiting, burns, hemorrahage
up to ____ of blood/water volume can be lost and compensatory measures will result to keep blood pressure and cardiac output sufficient
10%
once blood/water loss exceeds _____ cardiac output and blood pressure drop dramatically and shock occurs
25%
blood maldistribution shock
when there is reduced peripheral vascular resistance, which results in pooling of blood in tissues and hypoperfusion of tissues
typically, blood maldistribution is associated with
significant peripheral vasodilation, which vastly increases the microvascular spaces and pools blood away from vital tissues
what are the categories of blood maldistribution shock
anaphylactic shock
neurogenic shock
septic shock
anaphylactic shock occurs secondary to ______ reaction where some type of allergen triggers interations with IgE and subsequently mast cells
Type I hypersensitivity
mast cells release _____ causing _____
histamine and serotonin causing vasodilation
neurogeinc shock
induced by trauma, particularly to CNS that causes a systemic autonomic discharge leading to peripheral vasodilation, venous pooling, and hypoperfusion of tissues
septic shock occurs secondary to
large amounts of substances released from microorganisms (often bacteria) that are infecting an animal, either locally or systemically
endotoxemia occurs most with
LPS with gram-negative bacteria
_______ from gram-positive bacteria
peptidoglycans and lipoteichoic acids
these substances produced by the bacteria do what exactly
bind to receptors (toll like receptors, CD14) which in turn release a milieu of inflammatory cytokines, active compliment, coagulation factors, and platelets that lead to vascular permeability changes, vasodilation, hypovolemia, and pooling go fblood
what do you expect in tissues of anaphylactic shock?
edema and hyperemia
what do you expect in neurogenic shock
congestion (hard to ID)
what do you expect in septic shock?
vasculitis, thrombosis, hyperemia/congestion, generalized r localized inflammation may be present
What is a hemorrhage
physical loss either internally or externally, of blood and blood consituents from the vascular compartments
what does hemorrhage occur from
loss of vascular integrity or from abnormal function of any of the major components of normal hemostasis including endothelium and blood vessels, platelets, and coagulation factors
hemorrhage by vessel rupture (rhexis) occurs following many types ofinjury to vessels to include
trauma, vascular insult by bacteria, bacterial toxins or viral replication in endothelium and many mescellaneous causes
hemorrhage by diapedesis
passage of RBC across blood vessel walls that occurs secondary to inflammation, congestion, or hyperemia; (minimal blood loss)
hemorrhage by loss of platelet numbers or function
severe thrombocytopenia, DIC, IMT, bone marrow diesease leads to inability to control blood loss following vascular damage; congenital platelet defect or acquired platelet function defect
hemorrhage by loss of normal coaglation factor amount or function
secondary to many disorders includingcongenital coagulation factor deficiency, goagulation factor loss of function; coagulation factor consumption, coagulation factor lack of production, liver insufficiency from a variety of causes
petechia
pinpoint (1-2) cutaneous hemorrhage often caused by diapedesis or small vascular injury
purpura
pinpoint (0.3 to 1 cm) to small cutaneous hemorrhage that is often specifically associated with infectious causes
ecchymosis
small cutaneous hemorrhage (2-3 cm) due to larger vascular injury
hemopericardium
hemorrhage into pericardial sac, which can lead to cadiac tamponade
hemothorax
hemorrhage into thoracic cavity
hemoadbomen (hemoperitoneum)
hemorrhage into abdominal cavity
hemoptysis
expectoration of blood filled secretions or sputum secondary to hemorrhage into the airways
hematemesis
blood filled vomit secondary to hemorrhage into stomach or upper GIT
hematochezia
passage of bright red blood from the anus secondary to hemorrhage into the lower gastrointestinal tract
melena
dark red to black blood filled stool secondary to hemorrhage into the upper GIT
hematuria
blood in urine secondary to hemorrhage into the urinary tract
hematoma
hemorrhage confined to a local space, often in subcutaneous tissues which leads to a pocket of fluid (blood) accumulation due to continuous blood flow into space or lack of drainage away from space
epistaxis
blood exuding from nares secondary to hemorrhage into the nasal cavity
hyphema
hemorrhage into anterior/posterior chamber or vitreous of eye
what will hemorrhage appear like grossly
blood filled body cavities, free blood within the GIT lumen, blood filled airways, petechiation, purpura, ecchymosis, and hemarthrosis would indicate hemorrhage
what will hemorrhage appear like microscopically
erythrocytes pooling outside of blood vessels, macrophages ingesting erythrocytes (erythrophagocytosis), hemosiderin or hematoidin within macrophages (chronic hemorrhage or free within tissues
