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
Define ecchymoses.
- large subcutaneous hemorrhages
- RBCs are phagocytosed
- breakdown of hemoglobin (red) => bilirubin (blue-green) => hemosidirin (yellow-brown) is characteristic of bruise color changes
Define embolism.
- substance in the vascular system carried to another site from the point of origin
List types of emboli.
- thromboembolism
- amniotic fluid: enters placental membrane or uterine vein rupture; serious complication of labor
- air: develops during surgery, decompression syndrome (scuba diving)
- fat and marrow: marrow vascular sinusoids release fat globules into circulation; caused by soft tissue crush injury or long bone injury
Define fat embolism syndrome.
- fatal
- systemic
- classic symptoms: respiratory, neurological, petechial rash, anemia, thrombocytopenia
Define infarction.
- area of ischemic necrosis (coagulative) in a tissue or organ
- due to arterial/venous occlusion
- majority are arterial thromboemboli associated
Define white infarct.
- ischemic
- arterial occlusion
- appears pale/white
- single blood supply
- appears in heart, spleen, kidney
Define red infarct.
- hemorrhagic
- venule or arterial occlusion
- appears red
- dual blood supply
- appears in lung, small intestine
List factors that influence development of an infarction.
- nature of vascular supply
- rate of occlusion development
- vulnerability of tissue to hypoxia
- oxygen content of blood
What factors determine clinical outcome of thrombosis?
degree of occlusion
- smaller occlusion will let enough blood by to keep the tissue alive
- if it’s larger, it may cause ischemia (unless there is collateral support)
size and location of blood vessel
- main artery occlusion (carotid) or important arteries (brain) may cause death, stroke
- smaller arteries with many collaterals may be asymptomatic
Define shock.
- systemic hypoperfusion of tissues
- caused by low CO, or low effective circulation BV
List the 3 most common forms of shock.
- cardiogenic: low CO due to pump failure
- hypovolemic: low CO due to loss of blood volume
- septic: systemic immune response to microbial infection leads to venous pooling and arterial dilation
What kind of hemorrhage is normal?
menstruation
Why could a patient have edema?
- increased hydrostatic pressure: CHF, DVT
- decreased colloid osmotic pressure: decreased albumin synthesis (liver disease, malnutrition), increased protein loss (nephrotic syndrome)
- lymphatic obstruction
- increased vascular permeability: inflammation
- sodium retention: renal failure
Describe how heart failure can lead to systemic edema.
- increases capillary hydrostatic pressure
2. decreases renal blood flow => activate R-A-A system => Na and H2O retention => increase blood volume
Describe how malnutrition, hepatic/nephrotic disorders can lead to systemic edema.
decreased plasma albumin => decreased plasma oncotic pressure
Describe how renal failure can lead to systemic edema.
Na and H2O retention => increased blood volume
What causes a hypercoagulable state?
- primary genetic factors
- secondary acquired factors
