Which of the following is not the function of large
intestine?
(1) absorption of some water, minerals and
certain drugs
(2) nutrient absorption
(3) secretion of mucus to lubricate faeces
(4) temporary storage of faeces in rectum
A person addict for alcohol gets his liver destroyed
because
Answers
Answer:
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Answer:
Introduction
The large intestine, also known as the colon, is part of the digestive tract. The digestive tract includes the mouth, esophagus, stomach, small intestine, large intestine, and rectum. The large intestine is approximately 5 feet long, making up one-fifth of the length of the gastrointestinal (GI) tract. The large intestine is responsible for processing indigestible food material (chyme) after most nutrients are absorbed in the small intestine. The large intestine is composed of 4 parts. It includes the cecum and ascending colon, transverse colon, descending colon, and sigmoid colon. The large intestine performs an essential role by absorbing water, vitamins, and electrolytes from waste material.[1][2][3][4]
Function
The large intestine has 3 primary functions: absorbing water and electrolytes, producing and absorbing vitamins, and forming and propelling feces toward the rectum for elimination. By the time indigestible materials have reached the colon, most nutrients and up to 90% of the water has been absorbed by the small intestine. The role of the ascending colon is to absorb the remaining water and other key nutrients from the indigestible material, solidifying it to form stool. The descending colon stores feces that will eventually be emptied into the rectum. The sigmoid colon contracts to increase the pressure inside the colon, causing the stool to move into the rectum. The rectum holds the feces awaiting elimination by defecation.
Mechanism
Motility
The intestinal wall is made up of multiple layers. The 4 layers of the large intestine from the lumen outward are the mucosa, submucosa, muscular layer, and serosa. The muscular layer is made up of 2 layers of smooth muscle, the inner, circular layer, and the outer, longitudinal layer. These layers contribute to the motility of the large intestine. There are 2 types of motility present in the colon, haustral contraction and mass movement. Haustra are saccules in the colon that give it its segmented appearance. Haustral contraction is activated by the presence of chyme and serves to move food slowly to the next haustra, along with mixing the chyme to help with water absorption. Mass movements are stronger and serve to move the chyme to the rectum quickly.
Absorption of Water and Electrolytes