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The absorption rate of ethanol is typically modeled as a first-order kinetic process depending on the concentration gradient and specific membrane. The rate of absorption is fastest in the duodenum and jejunum, owing to the larger absorption surface area provided by the villi and microvilli of the small intestines.
[1] [2] The effect is most associated with orally administered medications, but some drugs still undergo first-pass metabolism even when delivered via an alternate route (e.g., IV, IM, etc.). [3] During this metabolism, drug is lost during the process of absorption which is generally related to the liver and gut wall. The liver is the major ...
The gastrointestinal tract is lined with epithelial cells. Drugs must pass through or permeate these cells to be absorbed into the bloodstream. Cell membranes may act as barriers to some drugs. They are essentially lipid bilayers which form semipermeable membranes. Pure lipid bilayers are generally permeable only to small, uncharged solutes.
In contrast, paracellular transport is the transfer of substances across an epithelium by passing through an intercellular space between the cells. It differs from transcellular transport, where the substances travel through the cell passing through both the apical membrane and basolateral membrane; Renal physiology. Transcellular transport is ...
Substances that are transported across the cell membrane by primary active transport include metal ions, such as Na +, K +, Mg 2+, and Ca 2+. These charged particles require ion pumps or ion channels to cross membranes and distribute through the body. Most of the enzymes that perform this type of transport are transmembrane ATPases.
A growing body of evidence has shown links between cancer and drinking alcohol. In a warning Friday, U.S. Surgeon General Vivek Murthy said cancer risk increases with the number of drinks, but ...
Murthy said alcohol use is the third leading cause of preventable cancer in the US, after smoking and obesity, and that alcohol products should carry warning labels similar to cigarettes.
Cell membranes are highly permeable to alcohol, so once alcohol is in the bloodstream it can diffuse into nearly every cell in the body. The concentration of alcohol in blood is measured via blood alcohol content (BAC). The amount and circumstances of consumption play a large part in determining the extent of intoxication; for example, eating a ...