七年制医学课件 病理生理 3edema.ppt

CHAPTER 2 EDEMA 1. Concept @ Edema refers to the accumulation of an abnormally large amount of fluid in : the interstitial space or cavities --- hydrothorax, hydroperitoneum (ascites). Presence of an abnormal accumulation of fluid within cells is referred to as cellular edema. Classification of edema Characteristics Effects of Edema Properties of Edema Fluid  Edema fluid can be placed in two categories: A. Exudates B. transudates Main Differences between Exudates and Transduates Effects of Edema Effects of edema on body depend on : type location extent rate of development lasting time of edema. ~ Can be divided into two aspects: beneficial harmful Beneficial Harmful Effects Beneficial Harmful Effects Structures functions of capillaries Formation of Interstitial fluid 1). Normally , effective colloid osmotic pressure =difference between and plasma interstitial fluid colloid osmotic pressure colloid osmotic pressure which tends to draw water into the vessels. 2). Capillary blood pressure (hydrostatic pressure) is the force that drives water through the capillary membrane into the tissue spaces. Hdrostatic pressure of interstitial fluid (tissue tension), which is much smaller, tends to oppose that in the capillaries. A: Blood pressure is greater than the colloid osmotic pressure, so that fluid is filtered from the plasma into the interstitial spaces. V: Hydrostatic pressure within the capillary is lower than the colloid osmotic pressue, and reab