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

Der Dünndarm und der Dickdarm sind für die Aufnahme von Nährstoffen und Wasser verantwortlich.
 Während der Dünndarm eher schmal ist, ist das Organ ungefähr 6,7m lang und in der Bauchhöhle zusammengedrückt.
 Der Chymus (Speisebrei) erreicht zuerst den Zwölffingerdarm und wandert dann zum mittleren und längsten Teil des Jejunums (Leerdarm).
 Hier enthält das Innenfutter Schleimhautfalten, in denen fingerartige Zotten liegen.
 Die darüber liegende Schicht von Epithelzellen weist zytoplasmatische Verlängerungen auf, die als Mikrovilli bezeichnet werden.
 Diese drei Strukturen vergrößern die Oberfläche des Dünndarms, um eine optimale Nährstoffaufnahme zu gewährleisten.
 Am Ende des Dünndarms befindet sich das Ileum, das über die Ileozökalklappe mit dem Dickdarm verbunden ist.
 Im ersten Teil des Dickdarms, dem Blinddarm, gibt es keine Falten oder Zotten.
 Es ist vielmehr die Heimat eines großen bakteriellen Ökosystems, das die letzten Stadien der Verdauung durchführt und dabei Zellulose abbaut.
 Am unteren Ende des Blinddarms baumelt der Appendix, eine kleine lymphatische Struktur.
 Darüber beginnt der aufsteigende Dickdarm, gefolgt vom Querdarm, der den größten Teil des restlichen Wassers und der Elektrolyte aufnimmt und Chymus in Kot verwandelt.
 Die letzten Regionen, absteigender Dickdarm, Sigmadarm und Rektum, lagern den Kot bis zur Ausscheidung durch den Anus.

Javitt, Norman B. "Geschichte der hepatischen Gallenbildung: Alte Probleme, neue Ansätze." Fortschritte in der Physiologieausbildung 38, Nr. 4 (1. Dezember 2014): 279–85. [<a href="https://doi.org/10.1152/advan.00076.2014">Quelle</a>]
Shetty, Sudarshan A., Floor Hugenholtz, Leo Lahti, Hauke Smidt und Willem M. de Vos. "Landschaftsgestaltung des Darmmikrobioms: Einblick in die Assemblage der Gemeinschaft und Implikationen für mikrobielle Modulationsstrategien." FEMS Microbiology Reviews 41, Nr. 2 (März 2017): 182–99. [<a href="https://doi.org/10.1093/femsre/fuw045" target="__blank">Quelle</a>]
Wen, Li und Andrew Duffy. "Faktoren, die die Darmmikrobiota, Entzündungen und Typ-2-Diabetes beeinflussen." Das Journal of Nutrition 147, Nr. 7 (Juli 2017): 1468S-1475S. [<a href="https://doi.org/10.3945/jn.116.240754" target="__blank">Quelle</a>]

anatomie der gedärme

Obwohl die Verdauung von Proteinen, Kohlenhydraten und Lipiden bereits im Magen beginnen kann, wird sie im Darm abgeschlossen. Auch die Aufnahme von Nährstoffen, Wasser und Elektrolyten aus der Nahrung und Getränken erfolgt im Darm. Der Darm kann in zwei strukturell unterschiedliche Organe unterteilt werden: den Dünn-und den Dickdarm.
 
 <h4>Der Dünndarm</h4>
 
 Der Dünndarm ist ein ungefähr 22 Meter langer Schlauch mit einem inneren Durchmesser von nur 2,5 cm. Da hier die meisten Nährstoffe absorbiert werden, ist die innere Auskleidung des Dünndarms stark gefaltet und mit fingerartigen Fortsätzen, den Zotten, überzogen. Sie enthalten jeweils weitere hunderte Mikrozotten. Die Falten, Zotten und Mikrovilli des Dünndarms vergrößern die Absorptionsoberfläche um das 60-bis 120-fache. Die vergrößerte Oberfläche bietet vielfältig Möglichkeit für die Absorption von Nährstoffen.
 
 Der Dünndarm verbindet sich mit dem Magen durch den Pylorus, den Magenpförtner. Dieser schließt sich, wenn Mageninhalt (Chymus) in den Zwölffingerdarm wandert. Dieser befindet sich am Anfang des Dünndarms. Der mittlere und größte Teil des Dünndarms ist das Jejunum. Das Ileum beendet den Dünndarm, wo er über die Ileozäkalklappe (Dickdarmklappe) in den Dickdarm übergeht.
 
 <h4>Der Dickdarm</h4>
 
 Der Dickdarm beginnt am Zökum. Der Blinddarm, eine kleine lymphatische Struktur, hängt an der Unterseite des Zökums. Oberhalb des Zökums beginnt der aufsteigende Dickdarm. Gefolgt wird dieser vom Querkolon. Diese Abschnitte nehmen den größten Teil des restlichen Wassers und der Elektrolyte aus dem Chymus auf und verwandeln ihn in Kot. Der absteigende Dickdarm, das Colon sigmoideum und der Enddarm lagern den Kot, bis dieser durch den Anus ausgeschieden wird.
 
 Insgesamt ist der Dickdarm ungefähr 1,5 m lang und hat einen Innendurchmesser von 4,8 cm. Er enthält keine Falten und Zotten. Die resorbierenden Epithelzellen haben jedoch Mikrovilli. Der Dickdarm beherbergt ein bakterielles Ökosystem, das die letzten Schritte der Verdauung durchführt. Dazu gehört der Abbau von Zellulose und Ballaststoffen. Das sind Stoffe, für deren Verarbeitung der Magen und der Dünndarm schlecht ausgerüstet sind.
 
 <h4>Bakterielle Vielfalt</h4>
 
 Der Dickdarm enthält über 700 verschiedene Bakterienarten. Man nimmt an, dass die bakterielle Vielfalt von Übergewicht und der Entwicklung von Typ 2 Diabetes abhängt. Fettleibige Menschen haben weniger Bakterienstämme als nicht fettleibige Menschen. Eine geringe Bakterienvielfalt wurde auch mit einer Insulinresistenz in Verbindung gebracht. Das bakterielle Darm-Ökosystem, das Darmbiom, wird kurz nach der Geburt etabliert. Dabei entwickeln die gestillten Babys ihr Darmbiom aus den in der Muttermilch vorhandenen Bakterien. Nach der Geburt wird das Biom durch die Genetik, die Ernährung, das Alter, das Geschlecht und das Immunsystem des Babys geformt. Äußere Faktoren wie Ernährung, Gesundheitszustand, Medikamente und geographische Lage beeinflussen ebenfalls signifikant die Komplexität des Darmbioms.

Anatomie der Gedärme

Obwohl die Verdauung von Proteinen, Kohlenhydraten und Lipiden im Magen beginnen kann, ist sie im Darm abgeschlossen. Die Aufnahme von Nährstoffen, Wasser, ...

Education

Lehre

JoVE Core

Biology

Biologie

Human Biology

Humanbiologie

Nutrition and Digestion

Ernährung und Verdauung

KEY TERMS AND CONCEPTS

KERNBEGRIFFE UND KONZEPTE

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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Die JoVE-Serie erweckt die Biologie durch über 300 prägnante und leicht verständliche animierte Video-Lektionen zum Leben, die Schlüsselkonzepte der Biologie erklären, sowie durch mehr als 150 Videos von Wissenschaftlern in der Praxis, die aktuelle Forschungsexperimente in den Labors von heute zeigen.

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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1. Obtain, evaluate, and communicate information to explain how differences in cellular structure (mitochondria, cytoskeletal structure, endoplasmic reticulum, cell membrane) lead to differences in the function and organization of the four tissue types (epithelial, connective, muscular, and nervous).

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2. Obtain, evaluate, and communicate information to describe how the structures of the integumentary system and its accessory organs contribute to its function. Examples: how the layers of the skin contribute to homeostasis, the role of glands in thermoregulation and in hydration of skin and mucous membranes, the protective functions of hair and nails

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a. Construct an explanation of the relationships between the integumentary system and other organ systems, including the body's mechanisms for maintaining homeostasis. Examples: Explain how changes in vessel diameter and evaporation of water over the skin contribute to thermoregulation (cardiovascular). Explain how sweat is used to excrete nitrogenous waste from the blood (cardiovascular). Explain how the skin and mucous membranes create a barrier against infection (immune system).

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3. Develop and use a model to illustrate how the structures of the skeletal system contribute to its function. Examples: Create a diagram or 3D model to illustrate bone shape, joint types, and bones in the appendicular and axial skeletons. Use models to illustrate the role of the skeletal system in movements around joints, support of a body structure, and protection of soft tissues.

9-12.HA.1.3

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a. Obtain, evaluate, and communicate information describing the growth and development of the skeletal system.

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9-12.HA.1.3.b

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9-12.HA.1.4

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a. Model the cellular physiology of skeletal muscle, including how the cell functions in muscle contraction and relaxation. Example: Use straws and paper to create a model of a sarcomere to illustrate how the fibers move during contraction and relaxation.

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9-12.HA.1.4.b

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5. Obtain, evaluate, and communicate information explaining the relationship between the structures and functions of the central nervous system and the peripheral nervous system.

9-12.HA.1.5

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a. Use a model to illustrate the role of action potentials in neural transmission. Clarification: Discussions of sodium-potassium pumps and ion channels are not required.

9-12.HA.1.5.a

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c. Construct an explanation of the role of neurotransmitters in the functions and behavior of the nervous system. Clarification: Discussion of classes of neurotransmitters is not required.

9-12.HA.1.5.c

Small and Large Intestine Functions

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