Which of the following is TRUE regarding the small intestine?
The small intestine secretes roughly the same volume of fluid as it absorbs
Segmentation is responsible for mixing the chyme and bringing it in contact with the intestinal wall for absorption
The most common form of small intestine motility is peristalic waves known as the migrating myoelectric complex (MMC)
The absorption of water molecules from the small intestine is primarily via mediated-transport
The most common form of small intestine motility is peristalic waves known as the migrating myoelectric complex (MMC)
To determine which statement is true regarding the small intestine, we can analyze each option individually:
1. "The small intestine secretes roughly the same volume of fluid as it absorbs":
The correct term for this process is absorption, not secretion. The small intestine is responsible for absorbing nutrients and fluids from the chyme (partially digested food) that enters from the stomach. Therefore, this statement is incorrect.
2. "Segmentation is responsible for mixing the chyme and bringing it in contact with the intestinal wall for absorption":
Segmentation is a process in the small intestine where it contracts and relaxes to mix the chyme with digestive juices and bring it into contact with the absorbent walls. This facilitates the absorption of nutrients into the bloodstream. As a result, this statement is true.
3. "The most common form of small intestine motility is peristaltic waves known as the migrating myoelectric complex (MMC)":
Peristaltic waves are muscular contractions that move the chyme through the digestive system. However, the migrating myoelectric complex (MMC) refers specifically to the pattern of peristaltic contractions that occur during periods of fasting to clear any remaining material from the small intestine. Therefore, this statement is incorrect as it misrepresents the MMC's role.
4. "The absorption of water molecules from the small intestine is primarily via mediated-transport":
Water absorption in the small intestine can occur through two main processes: passive diffusion and osmosis. Mediated-transport refers to a specific mechanism where molecules are transported across the cell membrane with the help of carrier proteins. However, water molecules are primarily absorbed through passive diffusion and osmosis in the small intestine. Therefore, this statement is incorrect.
In conclusion, the only true statement regarding the small intestine from the options provided is: "Segmentation is responsible for mixing the chyme and bringing it in contact with the intestinal wall for absorption."