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3_GI Tract in Health_Small_Large_Intestine

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The gastrointestinal tract is made up of various digestive organs such as the esophagus, stomach, pancreas, gallbladder, liver, small intestine, and large intestine. The small intestine, which is about 20-25 feet long, plays important roles in digestion and absorption of nutrients and water. It is divided into three sections: the duodenum, jejunum, and ileum. The duodenum receives bile and pancreatic enzymes, breaks down food, and absorbs nutrients. The jejunum is responsible for the absorption of carbohydrates, fats, proteins, minerals, and some vitamins. It has no clear demarcation between the jejunum and ileum. The ileum is the final part of the small intestine and continues the absorption of nutrients, specifically bile salts, fat-soluble vitamins, and vitamin B12.<br /><br />The large intestine, also known as the colon, is the last part of the gastrointestinal tract. It is around 4-5 feet long and functions to absorb water and electrolytes and eliminate solid waste. Motility in the gastrointestinal tract relies on peristalsis, which is the coordinated contraction and relaxation of smooth muscles, helping with mixing and propelling the contents downstream.<br /><br />The rectum and anus are responsible for retaining and releasing stool. The rectum holds the stool until it is time for elimination, and the anus has both voluntary and involuntary control through the internal and external anal sphincters.<br /><br />Defecation, or the process of passing stool, involves the relaxation of the internal and external anal sphincters and the descent of the pelvic floor muscles. Straining can also contribute to the process.<br /><br />Overall, understanding the anatomy and physiology of the gastrointestinal tract helps in comprehending the functions and processes involved in digestion, absorption, and elimination.

Keywords

gastrointestinal tract

small intestine

large intestine

absorption of nutrients

peristalsis

rectum

anus

defecation

digestion

elimination