Name: small and large intestine functions
Uploaded: 2019-03-11T09:21:25.000Z
Duration: 1 min 23 s
Channel: JoVE

K12 Standards

Alabama Course of Study Science

9-12

Human Anatomy and Physiology

from-molecules-to-organisms-structures-and-processes

From Molecules to Organisms: Structures and Processes

9-12.HA.1.10

Anatomy of the Intestines

小腸と大腸は 養分と水分を吸収する役割があります。小腸は比較的狭いですが およそ22フィートの長さで 腹腔に詰め込まれています。消化された食物はまず十二指腸に運ばれ 最も長い部分である 空腸を通過します。腸の内側には粘膜のひだがあり 指の形をした柔毛で覆われています。表面の上皮細胞には 微絨毛と呼ばれる突起があります。これらの3つの構造により 小腸の表層部は 養分を最適に吸収しやすくなります。小腸の終わりには回腸があり 回盲弁で大腸と繋がっています。大腸の始まりの部分は盲腸であり ひだや柔毛はありません。かわりに、多くのバクテリアが住みついていて 消化の最終段階として セルロースを破壊します。盲腸の下端にぶらさっがているのは虫垂であり 小さなリンパ管の構造をしています。その上部から上行結腸が始まり 横行結腸が続き 残りの水分や電解質のほとんどを吸収し 消化された食物を便に変えます。最後の部位は、下行結腸、S状結腸、直腸であり 肛門を通して排便されるまで便をためておきます。

Javitt、Norman B.「肝臓胆汁形成の歴史:古い問題、新しいアプローチ」 生理学教育の進歩 38、no. 4(2014年12月1日):279–85。[<a href="https://doi.org/10.1152/advan.00076.2014">ソース</a>]
Shetty, Sudarshan A., Floor Hugenholtz, Leo Lahti, Hauke Smidt, and Willem M. de Vos. "腸内細菌叢の造園: コミュニティ集合の洞察と微生物調節戦略への影響" FEMS Microbiology Reviews 41, no. 2 (March 2017): 182–99.[<a href="https://doi.org/10.1093/femsre/fuw045" target="__blank">ソース</a>]
「腸内細菌叢、炎症、および2型糖尿病に影響を与える要因」 Journal of Nutrition 147、no. 7(2017年7月):1468S-1475S。[<a href="https://doi.org/10.3945/jn.116.240754" target="__blank">ソース</a>]

腸の解剖

タンパク質、糖質、脂質などの消化は胃で始まり、腸で完了します。また、食べ物や飲み物からの栄養分、水分、電解質の吸収も腸で行われます。腸は、構造的に小腸と大腸の2つの器官に分けられます。 
 
 <h4>小腸</h4>
 
 小腸は長さ約22メートル、内径約2.5センチの管です。ほとんどの栄養素はここで吸収されるので、小腸の内壁は非常に複雑で、数百個の微絨毛を含む絨毛と呼ばれる指のような延長部で覆われています。小腸のひだ、絨毛、微絨毛によって、吸収のための表面積は60〜120倍にもなります。
 
 小腸は幽門括約筋によって胃とつながっており、血液が十二指腸（小腸の始まり）に移動すると幽門括約筋が閉まります。小腸の真ん中で最も大きい部分は空腸です。回腸は小腸の最後に位置し、回腸弁によって大腸に接続されています。
 
 <h4>大腸</h4>
 
 大腸は盲腸から始まります。盲腸の底には、小さなリンパ管である虫垂がぶら下がっています。盲腸の上には、上行結腸があり、次に横行結腸があります。盲腸の上には、上行結腸、横行結腸があり、これらの結腸は生理食塩水に含まれる水分と電解質のほとんどを吸収し、便にします。下行結腸、S状結腸、直腸は、肛門から排泄されるまで便を貯蔵します。
 
 大腸は全体で長さ約1.5m、内径4.8cmで、ひだや絨毛はないですが、吸収上皮細胞には微絨毛があります。大腸には細菌の生態系があり、胃や小腸では処理しきれないセルロースや食物繊維を分解し、消化の最終段階を行います。 
 
 <h4>細菌の多様性</h4>
 
 大腸には700種類以上の細菌が生息しています。細菌の多様性は、肥満や2型糖尿病の発症に関係していると考えられています。肥満の人は、非肥満の人に比べて細菌の種類が少ないのです。また、細菌の多様性の低さは、インスリン抵抗性と関連しています。腸内細菌の生態系である腸内バイオームは、生後まもなく確立されます。母乳で育てられた赤ちゃんは、母乳に含まれる細菌から腸内バイオームを形成します。生後、バイオームは個人の遺伝、食事、年齢、性別、免疫システムによって形成されます。また、食生活、健康状態、投薬、地理的条件などの外的要因も、腸内細菌叢の複雑さに大きく影響します。

タンパク質、炭水化物、脂質の消化は胃で始まるかもしれませんが、腸で完了します。栄養素、水、...

Education

JoVE Core

Biology

生物学

Human Biology

ヒト生物学

Nutrition and Digestion

栄養と消化

KEY TERMS AND CONCEPTS

主要用語と概念

small and large intestine functions

The small and large intestines complete digestion and absorb nutrients, water, and electrolytes. They are two structurally distinct organs with different shapes and jobs. Together, they move food material from the stomach toward elimination.

The small intestine is about 7 meters long and has an inner diameter of only 2.5 cm. Most nutrient absorption happens here, so its inner lining is highly folded and covered with villi, which are finger-like projections. Each villus contains hundreds of microvilli, and the folds, villi, and microvilli increase the surface area for absorption by 60 to 120 times.

The small intestine connects to the stomach through the pyloric sphincter. When chyme moves into the duodenum, which is the start of the small intestine, this sphincter closes off. The middle section is the jejunum, and the ileum is the final part. The ileum joins the large intestine at the ileocecal valve.

The large intestine begins at the cecum. The appendix, a small lymphatic structure, hangs from the bottom of the cecum. Above it are the ascending colon and then the transverse colon. These sections absorb most of the remaining water and electrolytes from chyme and help turn it into feces.

The descending colon, sigmoid colon, and rectum store feces until they leave the body through the anus. The large intestine is about 1.5 m long and has an inner diameter of 4.8 cm. Unlike the small intestine, it does not have folds or villi, although its absorptive epithelial cells do have microvilli.

The large intestine also supports a bacterial ecosystem that carries out the final stages of digestion. These bacteria can break down cellulose and fiber, which the stomach and small intestine are not well equipped to process. The large intestine contains over 700 different species of bacteria, and this diversity may be linked to obesity and Type 2 diabetes. People with obesity tend to have fewer bacterial strains than people who are not obese, and low diversity has also been associated with insulin resistance.

The gut biome is established shortly after birth. Babies who are breastfed develop it from bacteria present in breast milk. After birth, genetics, diet, age, sex, and the immune system help shape the biome. External factors such as diet, health status, medications, and geographical location also affect how complex the gut biome becomes.

Small and Large Intestine Functions

overview of human digestion

Saliva, Stomach Acid, and Gut Health

The human digestive system is monogastric, which means the stomach has one chamber for digestion. Several other animals also have monogastric digestive systems, including pigs, horses, dogs, and birds. This chapter focuses on the human digestive system. Saliva is a watery fluid released by the salivary glands into the mouth. It is about 99.5% water and also contains electrolytes, mucus, white blood cells, epithelial cells, enzymes, and antimicrobial agents. The enzymes in saliva begin...

anatomy of the intestines

The small and large intestines complete digestion and absorb nutrients, water, and electrolytes. They are two structurally distinct organs with different shapes and jobs. Together, they move food material from the stomach toward elimination. The small intestine is about 7 meters long and has an inner diameter of only 2.5 cm. Most nutrient absorption happens here, so its inner lining is highly folded and covered with villi, which are finger-like projections. Each villus contains hundreds of...

accessory organs

Digestive Glands and Enzymes

Digestive glands and accessory organs help break down food even though food does not pass through them. They add enzymes and other fluids to the digestive tract to support digestion. The salivary glands release saliva, a fluid that contains water, mucus, and amylase. Amylase is a digestive enzyme that starts breaking down starches and other carbohydrates before food reaches the stomach. The liver, gallbladder, and pancreas also support digestion. They send their secretions into the duodenum,...

lipid digestion

Lipases and Bile in Fat Breakdown

Lipases and bile help the body break down lipids, which are large molecules that do not mix well with water. Because most digestive enzymes are water-based, lipids need special steps before the body can use them. Lingual lipase is an enzyme made by acinar cells in the sublingual gland. It is found in saliva, but it has only a small role in the mouth. Its best pH, or acidity level, is 3.5-6.0, so it becomes active after chewed food reaches the acidic stomach. Gastric lipase is another acidic...

protein digestion

Protein Breakdown and Amino Acid Use

Protein digestion starts in the stomach, where strong acid helps unfold protein structure and expose peptide bonds in polypeptide chains. Digestive enzymes then begin breaking those chains into smaller pieces that can be processed by the body. Pepsin is a protease, which means it is a protein-digesting enzyme. It is made in the stomach and works with chymotrypsin and trypsin, enzymes released in the small intestine. These enzymes cut specific links between amino acids and form shorter...

carbohydrate digestion

Carbohydrate Breakdown in the Digestive Tract

Carbohydrate digestion breaks food carbohydrates into saccharides, or sugars, that the body can use for energy. It begins in the mouth during mastication, which means chewing. The masticated carbohydrates then pass through the stomach without being broken down further. Digestion starts again in the duodenum, the first part of the small intestine. There, pancreatic alpha-amylase and brush border enzymes on the microvilli help convert complex carbohydrates into monosaccharides. These simple...

neural regulation

Brain and Gut Control of Digestion

Brain and gut control digestion through a cephalic phase and the enteric nervous system. The cephalic phase begins when the brain sees or smells food. It sends impulses through cranial nerves to the salivary glands and stomach so the body is ready to eat. This first response is a conditioned, or learned, reaction to familiar foods. Appetite also changes the response. People may make more saliva and hear more stomach rumbling when they think about apple pie than broccoli. The hypothalamus and...

hormonal regulation

Digestive Hormones and Stomach Control

Digestive hormones control when the stomach makes acid and when food moves into the small intestine. They work with the neuroendocrine system, which links nerve signals and hormone release during digestion. In the stomach, proteins are detected by sensory neurons in the enteric nervous system. This stimulates the pyloric gland to release gastrin. Gastrin then helps trigger histamine release, and together they start hydrochloric acid production. The acid helps break food down into chyme. As the...

key terms and concepts

Explore how the small and large intestines absorb nutrients, water, and electrolytes, and learn how gut bacteria help finish digestion in high school biology.

Small and Large Intestine Functions | JoVE K12

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JoVE Core シリーズは、生物学の重要な概念を説明する 300 を超える簡潔でわかりやすいアニメーション ビデオ レッスンに加え、今日の研究室で行われる実際の研究実験を示す 150 以上の科学者の活動ビデオを通じて、生物学に命を吹き込みます。

Next Generation Science Standards

High School

Life Science

HS-LS1-2

Florida Department of Education

SC.912.L.14

SC.912.L.14.45

new-york-state-science-learning-standards

New York State Science Learning Standards

Structure and Function

HS-LS1-2.

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Small and Large Intestine Functions

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