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

Тонкий и толстый кишечники отвечают за поглощение питательных веществ и воды. Хотя тонкий кишечник довольно узок, длина органа составляет приблизительно 22 фута, он сложен в брюшной полости. Химус сначала достигает двенадцатиперстной кишки, а затем путешествует к среднему и самому длинному отделу, тощей кишке.Здесь внутренняя выстилка содержит слизистые складки, которые покрыты пальчиковыми вилли. Верхний слой эпителиальных клеток имеет цитоплазматические расширения, называемые микровилли. Эти три структуры увеличивают площадь поверхности тонкого кишечника, чтобы обеспечить оптимальное всасывание питательных веществ.В конце тонкого кишечника находится илеум, который прикрепляется к толстому кишечнику с помощью илеокального клапана. В первой части толстой кишки, слепой кишке, нет складок или ворсинок. Свисает в нижней части слепой кишки, аппендикс, небольшая лимфатическая структура.Над ним начинается восходящая ободочная кишка, после чего следует поперечная толстая кишка, которая поглощает большую часть оставшейся воды и электролитов, превращая химус в фекалии. Последние области, нисходящая ободочная кишка, сигмоидная толстая кишка и прямая кишка удерживают фекалии до устранения через анус.

Джавитт, Норман Б. "История образования печеночной желчи: старые проблемы, новые подходы." Успехи в образовании в области физиологии 38, No4 (1 декабря 2014 г.): 279–85. [<a href="https://doi.org/10.1152/advan.00076.2014">исходник</a>]
Шетти, Сударшан А., Флор Хугенхольц, Лео Лахти, Хауке Шмидт и Виллем М. де Вос. "Ландшафтный дизайн кишечного микробиома: понимание сообщества и последствия для стратегий микробной модуляции." FEMS Microbiology Reviews 41, No2 (март 2017 г.): 182–99. [<a href="https://doi.org/10.1093/femsre/fuw045" target="__blank">Источник</a>]
Вэнь, Ли и Эндрю Даффи. «Факторы, влияющие на микробиоту кишечника, воспаление и диабет 2 типа». Журнал питания 147, No 7 (июль 2017 г.): 1468S-1475S. [<a href="https://doi.org/10.3945/jn.116.240754" target="__blank">Источник</a>]

Анатомическое строение кишечника

Хотя переваривание белков, углеводов и липидов может начаться в желудке, оно завершается в кишечнике. Поглощение питательных веществ, воды и электролитов из пищи и питья также происходит в кишечнике. Кишечник можно разделить на два структурно различных органа – тонкий и толстой кишки.

<h4>Тонкий кишечник</h4>

 Тонкая кишка представляет собой трубку длиной ~ 22 метра с внутренним диаметром всего 2,5 см. Поскольку здесь всасывается большинство питательных веществ, внутренняя оболочка тонкой кишки очень извилистая и покрыта пальцами, называемыми ворсинками, каждая из которых содержит сотни микроворсинок. Складки, ворсинки и микроворсинки тонкой кишки увеличивают площадь абсорбции в 60–120 раз. Увеличенная площадь поверхности дает хорошие возможности для усвоения питательных веществ. 

 Тонкая кишка соединяется с желудком пилорическим сфинктером, который закрывается, когда химус попадает в двенадцатиперстную кишку - начало тонкой кишки. Средняя и самая большая часть тонкой кишки - тощая кишка. Подвздошная кишка заканчивается тонкой кишкой, где она прикрепляется к толстой кишке с помощью илеоцекального клапана. 

<h4> Толстый кишечник </h4>

 Толстый кишечник начинается от слепой кишки. Аппендикс, небольшая лимфатическая структура, свисает со дна слепой кишки. Выше слепой кишки начинается восходящая ободочная кишка, за которой следует поперечная ободочная кишка. Они поглощают большую часть оставшейся воды и электролитов из химуса, превращая его в кал. Нисходящая ободочная, сигмовидная и прямая кишки хранят фекалии до тех пор, пока они не будут выведены через задний проход. 

 В целом толстая кишка имеет длину около 1,5 м и внутренний диаметр 4,8 см. Он не содержит складок и ворсинок, но абсорбирующие эпителиальные клетки имеют микроворсинки. В толстой кишке обитает бактериальная экосистема, которая выполняет заключительные этапы пищеварения - расщепление целлюлозы и клетчатки - соединений, которые желудок и тонкий кишечник плохо приспособлены для обработки. 

<h4> Разнообразие бактерий </h4>

 В толстом кишечнике содержится более 700 различных видов бактерий. Считается, что разнообразие бактерий связано с ожирением и развитием диабета 2 типа. У людей с ожирением меньше штаммов бактерий, чем у их коллег, не страдающих ожирением. Низкое бактериальное разнообразие также связано с инсулинорезистентностью. Бактериальная экосистема кишечника - биом кишечника - формируется вскоре после рождения, при этом у этих младенцев, находящихся на грудном вскармливании, развивается биом кишечника из бактерий, присутствующих в грудном молоке. После рождения биом человека формируется генетикой, диетой, возрастом, полом и иммунной системой человека. Внешние факторы, такие как диета, состояние здоровья, лекарства и географическое положение, также значительно влияют на сложность биома кишечника.

Хотя переваривание белков, углеводов и липидов может начинаться в желудке, оно завершается в кишечнике. Усвоение питательных веществ, воды, ...

Education

JoVE Core

Biology

Биология

Human Biology

Биология человека

Nutrition and Digestion

Питание и пищеварение

KEY TERMS AND CONCEPTS

ОСНОВНЫЕ ТЕРМИНЫ И ПОНЯТИЯ

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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Florida Department of Education

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Structural Organization of the Human Body: An Overview

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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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Accessory Structures of the Skin: Sweat Glands

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Accessory Structures of the Skin: Nails

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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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Joints

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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.

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Bone Formation by Endochondral Ossification

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Bone Formation by Intramembranous Ossification

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Bone Remodeling and Repair

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

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b. Construct an explanation of the relationships between the skeletal system and other organ systems, including the body's mechanisms for maintaining homeostasis. Examples: Explain the role of spongy bone in hematopoiesis (cardiovascular system) and leukopoiesis (immune system). Explain how the storage of minerals in bone contributes to homeostasis.

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Fascicle Arrangement in Skeletal Muscles

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4. Develop and build a three-dimensional model to illustrate the structures of the muscular system, including muscle locations, origins, and insertions, and explain their roles in movement and support. Example: Design and build a model of a lever to illustrate the relationship between bones and muscles and explain their roles in body movement and support.

9-12.HA.1.4

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The Sarcomere

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Excitation-Contraction Coupling in Skeletal Muscles

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Relaxation of Skeletal Muscles

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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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b. Obtain, evaluate, and communicate information to explain muscle fatigue and tone in terms of muscle cell physiology.

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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.

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b. Construct an explanation of the role of reflex arcs, the central nervous system, and special senses in the response to stimuli to maintain homeostasis and guide behavior. Example: smelling a strong odor initiating a sneeze response using a reflex arc; pupil diameter changing in relation to the amount of light entering the eye Clarification: Discussion of the anatomy and physiology of the sensory organs is not required.

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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

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d. Obtain, evaluate, and summarize scientific findings regarding the biological origin of emotions and memories in distinct regions of the brain. Examples: the role of the frontal lobe in emotional regulation, the regulation of fear response by the amygdala

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Small and Large Intestine Functions

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