Disorders of Circulation Flashcards
Define hyperemia. Provide clinical examples.
- dilation of an artery/arteriole leading to increased blood flow in the capillary beds
- caused by sympathetic neuronal discharge or chemical mediators
- area appears red due to increased amount of oxygenated blood to the area
- ex: acute inflammation, body dissipating heat, blushing
Define congestion. Provide clinical examples.
- impaired venous drainage due to inability of vessel to dilate => pooling of blood
- caused by sympathetic neuronal discharge or chemical mediators
- area appears red-blue due to increased amount of deoxygenated blood
- can be systemic/local or acute/chronic
- ex: congestive heart failure, poor venous drainage
Active hyperemia is __________. Passive hyperemia is __________.
active = hyperemia passive = congestion
What causes chronic passive congestion? What can it lead to?
- right heart failure
- blood backs up into organs: liver, lungs, spleen
- leads to ischemia b/c stretched sinusoids push adjacent cells => not getting enough O2
Define edema. How does it relate to lymphatics?
abnormal accumulation of fluid leakage from blood vessels into interstitial space
- when amount of fluid leaked > lymphatic clearance => edema
Describe normal physiology of fluid movement across vessel walls.
Forces involved:
- capillary hydrostatic pressure
- interstitial hydrostatic pressure
- capillary plasma colloid pressure (osmotic)
- interstitial colloid osmotic pressure
These forces remain in near equilibrium so that only slight amounts of fluid leak from vessels. Small amount is removed by lymphatics.
Define noninflammatory edema.
- due to changes in hydrostatic or osmotic pressure
- called transudate
- protein-poor
Define inflammatory edema.
- increased intraendothelial space (between endothelial cells)
- due to chemical mediators of the inflammatory process => increased vascular permeability and blood flow
- called exudate
- rich with proteins and cells
Define hemorrhage.
- flow of blood from a ruptured vessel into tissue, body cavity, or external environment
- caused by mechanical injury (congestion, trauma) or pathology (inflammation releases proteases, neoplasm erodes vessel)
Define hemostasis. What 3 factors regulate it?
- balance of fluid leakage and clotting in the body
- maintains blood in liquid state
- prevents uncontrolled bleeding
- if abnormal, can predispose to bleeding
3 factors
- vascular wall
- platelets
- coagulation cascade
Define thrombosis.
- formation of a blood clot (thrombus) within the vascular system
List the mechanisms of thrombosis formation (Wirchow’s triad)
- endothelial injury: inflammation, atherosclerosis
- altered blood flow: turbulence (loss of laminar flow) vs. stasis (lazy river)
- hypercoagulable state: predisposed to easy clot formation (protein C deficiency, birth control + smoking)
What are the possible fates of a thrombus?
- propagation - enlarged thrombus increases odds of occlusion or embolization
- dissolution - body uses fibrin to shrink or dissolve thrombus; over time, it becomes resistant
- embolization - part or all of thrombus travels elsewhere
- organization - smooth muscle cells, endothelial cells, and fibroblasts grown within and around the thrombus (weeks-months)
- recanalization - smaller capillaries form to reestablish flow within the lumen (weeks-months)
Define petechiae
- minute hemorrhages in skin, mucosal/serous surfaces
- causes: low platelets count, defective platelet, loss of vascular wall support
Define purpura.
- medium hemorrhages
- causes: same as petechiae, trauma, inflammation
