Absorption of Water and Electrolytes. ... Sodium is absorbed from the intestinal lumen by several mechanisms, most prominently by cotransport with glucose and amino acids, and by Na+/H+ exchange, both of which move sodium from the lumen into the enterocyte.
Large Intestine
Water is always absorbed in the alimentary tract through passive osmosis via a mostly paracellular route between enterocyte tight junctions. Consequently, water absorption is primarily actuated by active absorption of osmotic electrolytes, especially sodium.
Absorption of Water and Electrolytes. The small intestine must absorb massive quantities of water. ... Net movement of water across cell membranes always occurs by osmosis, and the fundamental concept needed to understand absorption in the small gut is that there is a tight coupling between water and solute absorption.
A majority of water's absorption into the bloodstream occurs after water passes through the stomach and on to the small intestine. The small intestine, at around 20 feet long, efficiently absorbs water into the cell membrane and bloodstream. ... Once absorbed into the body, water aids a number of vital functions.
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