Section 6

Edema

• Edema is a fluid accumulation in the interstitial spaces
• Edema formation is influenced by hydrostatic and oncotic pressures
• Increased hydrostatic pressure or decreased oncotic pressure leads to edema formation
• Hydrostatic Edema: Increased hydrostatic pressure at the venous end of capillaries hinders reabsorption
• Oncotic Edema: Reduction in plasma osmotic pressure due to albumin loss or deficiency causes fluid retention
• Lymphatic Edema: Lymphatic obstruction prohibits fluid resorption, leading to interstitial fluid accumulation

Localized vs Generalized Edema

• Localized: Specific area, caused by factors like vascular obstruction or lymphatic blockage
• Generalized: Systemic, caused by heart failure, decreased oncotic pressure, or sodium retention

Transudate vs Exudate

• Transudate: Protein-poor fluid due to high hydrostatic pressure or low colloid osmotic pressure
• Exudate: Protein-rich fluid due to increased vascular permeability

Hemorrhage

• Hemorrhage refers to bleeding outside the blood vessels
• It can be caused by damage to blood vessels, weakening of vessels due to conditions like atherosclerosis, infections, invasive tumors, hypertension, or hemorrhagic diatheses

Thrombosis

• Thrombus is a blood clot formed within a blood vessel
• Components of a Thrombus: Red blood cells, white blood cells, platelets, and fibrin
• Virchow's Triad: Factors promoting thrombosis: endothelial injury, abnormal blood flow, and hypercoagulability

Prognosis of Thrombosis

• Propagation: Thrombus enlarges
• Embolization: Thrombus fragment detaches and travels through the bloodstream
• Dissolution: Thrombus dissolves
• Organization and Recanalization: Tissue replaces the thrombus, forming new channels for blood flow

Complications of Thrombi

• Embolization: Fragments of the thrombus break off and travel in the bloodstream
• Ischemic injury: Reduced blood flow leading to tissue damage
• Infarction: Tissue death due to complete lack of blood flow

Embolism

• An embolus is a detached intravascular mass traveling through the bloodstream
• Types: Thromboemboli, Gas, Fat, Tumor, Foreign Body

Ischemia

• Ischemia is restricted or reduced blood flow to an area of tissue
• Causes: Decreased blood supply, obstruction due to thrombus, embolus, pressure, or vessel wall damage
• Prognosis: No effect if alternate blood supply exists, but severe or complete ischemia can lead to infarction

Infarction

• Infarct is an area of necrotic tissue due to occlusion of the vascular supply
• It is irreversible and replaced by scar tissue
• Classification:
  • Red (hemorrhagic): Venous or arterial occlusion, tissues with dual blood supply, previously congested tissue, re-established flow after infarction.
  • White (anemic): Arterial occlusion in solid organs
  • Septic: Microbial infection causing abscess formation
  • Bland: No microbial infection

Influencing Factors of Infarct Development

• Anatomy of the vascular supply
• Rate of occlusion
• Tissue vulnerability to hypoxia

Shock

• Shock is a life-threatening condition characterized by diminished cardiac output and reduced effective circulating blood volume
• It leads to impaired tissue perfusion and cellular hypoxia
• Categories:
  • Cardiogenic: Heart failure due to myocardial damage, compression, or outflow obstruction
  • Hypovolemic: Loss of blood or plasma volume
  • Septic: Triggers by infections, associated with severe systemic inflammatory response
  • Anaphylactic: Severe allergic reaction, rapid drop in blood pressure, and widespread vasodilation.
  • Neurogenic: Damage to the nervous system resulting in vasodilation and decreased blood pressure.

This quiz explores the mechanisms behind edema, including hydrostatic and oncotic pressures, and distinguishes between localized and generalized edema. Additionally, it discusses the differences between transudate and exudate, fostering a comprehensive understanding of fluid accumulation in tissues.