Small+Intestine

= Small Intestine: by Katie, Nick, James and Brendan = What is the Small Intestine? Anatomical Structure and Location.

The small intestine is about 2.5cm in diameter and 6m long. Its job is to absorb most of the nutrients from what we eat and drink. Velvety tissue lines the small intestine, which is divided into the duodenum, jejunum, and ileum

The small intestine is located in the digestion tract; it fills most of the abdomen. The intestine can be divided into three areas, the Duodenum (the first section), the Jejunum (the middle section) and it concludes with the Ileum.

The small intestine is inferior to the stomach, liver and the oesophagus. It is also superior to the anus and the rectum.

Intestinal villus refers to any one of the small, finger-shaped outgrowths of the epithelial lining of the wall of the intestine. A cluster of these projections are referred to as Intestinal villi. Each of these range from 0.5-1.6 mm in length and extends about 1 mm into the lumen, which is an empty cavity or tubular passage of the intestine. These projections are tubular and thread-like in form. These are tiny and have a very complex structure. Each villus comprises of a lymphatic vessel and a capillary bed. The outer surface of the villi is topped with layers of cells



Function of the Small Intestine:


 * Duodenum:**

The Duodenum is the first part of the small intestine; it precedes the Jejunum and the Ilium. The Duodenum is largely responsible for the breakdown of food within the small intestine using enzyme chemicals. The Duodenum is composed of a very thin layer of cells, with glads that secret the liquids need for the break -down of foods. The Duodenum is the primary regulator for the emptying of the contents within the stomach. Chemicals such as [|Secretin] and [|cholecystokinin] are released from cells in the duodenum in response to acidic and fatty stimuli present there when the [|pylorus] sphincter opens and releases gastric fluids into the duodenum for further digestion. These cause the [|liver] and [|gall bladder] to release [|bile], and the [|pancreas] to release bicarbonate and digestive enzymes such as [|trypsin], [|lipase] and [|amylase] into the duodenum as they are needed. In the diagram below the Duodenum is shaded in pink.



The Jejunum is the second section of the small intestine comprising about 2/5 of the total length of the small intestine. The Jejunum specialises in the absorption of carbohydrates and proteins as well as other nutrients such as Amino Acids, sugers, fatty acid particles, vitamins, minerals, electrolytes and water. Basically the function is to absorb the nutrients that have been processed in the duodenum, stomach and oral cavity and by allowing them to pass through the walls into the bloodstream.
 * Jejunum:**

The Ileum is responsible for the absorbtion of vitamin b12 and reabsorbsion of bile salts. It's perisalsis contractions are slower in this section meaning the food spends more time here. = = Helpful Links [] [] [] [] [] (an animation) [] (animation and questions) [] (quiz – 6 questions) [] [] [] @http://nature.ca/discover/exm/blddgstvsystm/index_e.cfm [] @http://www.anatomyarcade.com/games/gamesDigestive.html
 * Ileum:**

Revision Questions: 1) What is the small intestine? What is the major part of digestion that takes place here? 2) What are the three main sections of the small intestine? Lable them on the diagrams below. 3) Where is the small intestine located? 4) What is the fuction of each part of the small intestine? Eg what is absorbed etc. 5) What is the diameter of the majority of the small intestine? 6)What are villi? 7) Which are the two major parts of the villi? 8) Which major organs is the small intestine inferier to? as well as superiour to? 9)Bile is secreated into the small intestine, where is this bile made and stored? 10)Secreations from an important organ are found in the small intestine. What is this organ?

Revision Answers 1) The part of the intestine that runs between the stomach and large intestine. Absorbsion of nutrients largely occurs here. 2) Duodenum, Jejunum and Ileum DIAGRAM:



3)The small intestine is located in the digestion tract; it fills most of the abdomen 4) Dueodenum: The duodenum is largely responsible for the breakdown of food within the small intestine using enzyme chemicals. Jejunum: The Jejunum specialises in the absorption of carbohydrates and proteins as well as other nutrients such as Amino Acids, sugers, fatty acid particles, vitamins, minerals, electrolytes and water Ileum: Ileum is responsible for the absorbtion of vitamin b12 and reabsorbsion of bile salts. It's perisalsis contractions are slower in this section meaning the food spends more time here.

5)2.5cm in diameter 6)Small, finger-shaped outgrowths of the epithelial lining of the wall of the intestine 7)The lumen and capillary bed. 8)The small intestine is inferior to the stomach, liver and the organs in the chest cavity. It is also superior to the anus and the rectum. 9)Made in the liver and stored in the gall bladder. 10)Pancreas