Disorders of Circulation Flashcards
Definition of hyperemia and congestion
Increased intravascular blood volume in tissue, an organ, or part of the body
What is hyperemia more specifically?
Dilatation of an artery or arteriole and increased blood flow into the capillaries
What causes active hyperemia?
Sympathetic neurogenic discharge or chemical mediators
Clinical examples of hyperemia
Acute inflammation of tissue, blushing, body’s need to disippate heat
How does hyperemic skin appear?
Red
What causes passive hyperemia?
(Congestion)
Impaired venous drainage due to active influence of sympathetic discharge or chemical mediator
What is the most common cause of congestion?
Right-sided heart failure
Definition of edema
Accumulation of abnormal amounts of fluid in interstitial spaces or body cavities
Forces that influence movement of fluid across the capillary wall
Capillary hydrostatic pressure
interstitial hydrostatic pressure
Plasma colloid osmotic pressure
Interstitial colloid osmotic pressure
What is the normal physiology of fluid distribution?
All the osmotic forces are near equilibrium and allows for most of the fluid to remain in the vascular compartment and what isn’t is cleared by lymphatics
Non-inflammatory edema
Fluid accumulates in the interstitium as a consequence of changes in hydrostatic pressure and colloid osmotic pressure
Transudate
Non-inflammatory edema
Inflammatory fluid accumulation
Tissue injury alters blood flow and vascular permeability as a result of increased interendothelial space, which is modulated by chemical mediators
Exudate
Inflammatory edema
Definition of hemorrhage
Flow of blood from a ruptured blood vessel; may flow into tissue, body cavity, or outside the body
Mechanism of hemorrhage
Occurs when a large or small blood vessel is disrupted by a mechanical force (trauma) or a pathological process (inflammation, neoplasm)
Bleeding diathesis
Abnormal hemostasis that causes a predisposition to bleeding
What is the only normal hemorrhage?
Menstruation
Hematoma
Solid swelling of clotted blood under the skin
Hemothorax
Accumulation of blood in the pleural cavity
Hemopericardium
Blood in the pericardial sac of the heart
Hemoperitoneum
Blood in the abdominal cavity
Hemarthrosis
Blood in the joint cavity
Petechiae
Small red or purple spots on the skin caused by ruptured capillaries
Purpura
Slightly larger red or purple spots on the skin caused by ruptured vessels
Ecchymosis
Discoloration under the skin caused by bleeding into tissues
Definition of thrombosis
Blood clot within an uninterrupted vascular system
Three mechanisms of thrombosis
Endothelial injury, altered blood flow, hypercoagulable state
Examples of endothelial injury as a mechanism of thrombosis
Inflammation, advanced atherosclerosis
Examples of altered blood flow as a mechanism of thrombosis
Turbulence vs. stasis: a-fib, bed rest
Examples of hypercoagulable state as a mechanism of thrombosis
Predisposition to easy clot formation: protein C deficiency, increased risk by OCPs and smoking
Four fates of a thrombus
Propagation
Dissolution
Embolization
Organization & recanalization
Define propagation. What are its consequences?
Thrombus enlarges, resulting in increased odd of vascular occlusion or embolization
Define dissolution
Activation of the body’s fibrinolytic system may lead to rapid shrinkage and even complete dissolution of a newly formed thrombus
What occurs over time as the thrombus is being dissolved?
Extensive fibrin polymerization renders the thrombus increasingly resistant to lysis/dissolution.
Define embolization (process of thrombosis)
Part or all of the thrombus is dislodged and travels elsewhere in the vasculature
Define organization and recanalization
Older thrombi become “organized” with the ingrowth of endothelial cells, smooth muscle cells, and fibroblasts into the thrombus. With time, small vascular channels are formed, reestablishing some flow in the lumen.
Definition of an embolism (separate definition)
Intravascular substance (solid, liquid, gas) which is carried by blood from a point of origin to a distant site.
Four types of emboli
Thromboembolism
Amniotic fluid
Gas
Fat and marrow embolism
Describe amniotic fluid as an embolism process.
Uncommon, serious complication of labor; amniotic fluid enters placental membranes and/or uterine vein rupture
Describe gas as an embolism process.
Gas bubbles within circulation obstruct vascular flow, which can develop during medical procedures or from decompression sickness
Describe fat and marrow embolisms
Happens s/p soft tissue crush injury or long bone injury where marrow vascular sinusoids release microscopic fat globules into circulation
Describe mortality of fat embolism syndrome
Systemic; fatal in 10+% of patients
Define infarction
Area of ischemic necrosis within tissue or an organ, produced by occlusion of either its arterial supply or venous drainage.
Majority of infarcts are associated with what?
Arterial occlusion by thromboembolism
Types of infarct
White (ischemic, arterial) and red (hemorrhagic, venous or arterial)
Four factors influencing development of an infarct
- Nature of vascular supply
- Rate of development of the occlusion
- Vulnerability of tissue to hypoxia
- Oxygen content of the blood
Clinical outcome of a thrombosis depends on which two factors?
Degree of occlusion and size/location of the blood vessel
Definition of shock
Final common pathway for a number of possible events which result in systemic hypoperfusion of tissues
What can cause shock?
Diminished cardiac output or reduced effective circulating blood volume
Three types of shock
Cardiogenic, hypovolemic, and septic
What causes septic shock?
Arteriolar vasodilation and venous blood pooling that stems from systemic immune response to microbial infection
