NURS 364 Lecture Notes - Lecture 11: Body Water, Lymph Node Biopsy, Oncotic Pressure
14 Dec 2017
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Document Summary
Body fluids are composed of water and various dissolved substances (solutes) Total body water constitutes about 60% of the total body weight. The average fluid intake and output is about 2500ml over a 24-hour period. However, protein (albumin) does not cross the capillary membrane and maintains the capillary oncotic pressure: water movement between plasma (vascular) & interstitial fluid. Two types of forces determine whether fluid will move in or out of the capillaries and interstitial spaces. Hydrostatic pressure pushes fluid (garden hose with a hole in it. If only a little pressure not much happens but a lot of pressure water shoots out) Directly proportional to amount of fluid: oncotic pressure pull fluid, maintained by protein (albumin)- albumin should not leak out of capillaries in a healthy state, water movement between plasma (vascular) & interstitial fluid. Capillary hydrostatic pressure pushes fluid out of the capillaries into the interstitial spaces. Interstitial hydrostatic pressure pushes fluid from interstitial spaces into the capillaries.
