wai keung asked in 科學及數學生物學 · 1 decade ago

關於消化系統

詳細講解消化系統

各個organ有咩用, 會分秘d咩juice出黎 etc.

in english

3 Answers

Rating
  • 1 decade ago
    Favorite Answer

    Salivary Glands

    The mouth contains the salivary glands which are accessory digestive glands that produce a fluid secretion called saliva.

    The Tooth

    The tooth can be broken down by acids produced by the mouth for digestive purposes. This process is called "decay". To prevent decay, good oral hygiene, consisting of daily brushing and flossing, is necessary.

    The Esophagus

    The esophagus is a muscular tube which carries food and liquids from the throat to the stomach for digestion after it has been chewed and chemically softened in the mouth.

    Stomach

    The stomach consists of layers of muscle and nerves that continue the breakdown of food which begins in the mouth.The stomach has several functions: (1) as a storage bin, holding a meal in the upper portion and releasing it a little at a time into the lower portion for processing; (2) as a food mixer, the strong muscles contract and mash the food into a sticky, slushy mass; (3) as a sterilizing system, where the cells in the stomach produce an acid which kills germs in "bad" food; (4) as a digestive tub, the stomach produces digestive fluid which splits and cracks the chemicals in food to be distributed as fuel for the body.

    Liver

    The liver cleanses the blood and processes nutritional molecules, which are distributed to the tissues. When we eat, more blood is diverted to the intestines to deal with digestive processes; when not eating, three-fourths of the blood supply to the liver comes from the intestines.

    Spleen

    The spleen is the largest of the lymphoid tissues. It is a valuable organ which produces some of the white blood cells, filters the blood, destroys old, worn-out red blood cells and returns needed iron to the blood, disposing of the rest as waste. The spleen also stores excess blood for emergencies; for example, when oxygen in the circulatory system is short.

    Small Intestine

    It is divided into three sections: (1) the duodenum, a receiving area for chemicals and partially digested food from the stomach; (2) the jejunum, where most of the nutrients are absorbed into the blood and (3) the ileum, where the remaining nutrients are absorbed before moving into the large intestine. The intestines process about 2.5 gallons of food, liquids and bodily waste every day. The small intestine also makes waves which move the food forward, but these are usually weak and infrequent to allow the food to stay in one place until the nutrients can be absorbed. If a toxic substance enters the small intestine, these movements may be strong and rapid to expel the poisons quickly.

    Large Intestine

    The large intestine, or colon, consists of ascending, transverse, descending, and sigmoid portions. Substances which have not been absorbed in the small intestine enter the large intestine in the form of liquid and fiber. The large intestine or "bowel" is sometimes called the "garbage dump" of the body, because the materials that reach it are of very small use to the body and are sent on to be disposed of. The first half of the colon absorbs fluids and recycles them into the blood stream. The second half compacts the wastes into feces, secretes mucus which binds the substances, and lubricates it to protect the colon and ease its passage.

    Rectum

    The rectum is a short, muscular tube that forms the lowest portion of the large intestine and connects it to the anus. Feces collects here until pressure on the rectal walls cause nerve impulses to pass to the brain, which then sends messages to the voluntary muscles in the anus to relax, permitting expulsion.

  • 1 decade ago

    Site of action: mouth

    Source: salivary gland

    Secretion: saliva

    Constituents and consequence:

    amylase: starch-->maltose

    lysozyme: attack bacterial cell wall

    mucus: lubrication of food mass

    hydrogencarbonate: buffer action provides almost neutral medium for the action of amylase; maintain correct pH

    Site of action: esophagus

    Source: wall of esophagus

    Secretion: mucus (lubrication)

    Function of esophagus: move food to stomach by peristaltic waves

    Site of action: stomach

    Source: gastric gland

    Secretion: gastric juice

    Constituents and consequence:

    HCl: provides acidic medium for the activites of protease; kill germs; stops the action of salivary amylase; activate protease

    mucus: protection of stomach lining against the action of protease

    protease: protein-->peptides+amino acids

    Site of action: duodenum

    Source: liver and pancreas

    Secretion: bile and pancreatic juice respectively

    Constituents and consequence:

    For bile:

    sodium bicarbonate: neutralization of stomach acid

    bile salts: emulsification, formation of micelles

    bile pigments: breakdown product of haemoglobin for excretion

    For pancreatic juice:

    amylase: starch-->maltose

    protease: protein-->peptides+amino acid

    peptidase: peptides-->amino acids

    lipase: fat-->fatty acids+monoglycerides

    Site of action: small intestine

    Source: wall of small intestine

    Secretion: intestinal juice

    Constituents and consequence:

    carbohydrases:

    -maltase: maltase-->glucose

    -sucrase: sucrase-->glucose

    -lactase: lactase-->glucose

    aminopeptidase: peptides-->amino acids

    lipase: fat-->fatty acids+monoglycerides

    mucus: lubrication of food mass; protection of intestinal lining aganist the action of enzymes

    Site of action: large intestine

    Source: wall of large intestine

    Secretion: mucus(lubrication)

    Functions of large intestine: storage and concentration of undigested matter; absorption of salt and water; mixing and propulsion of contents; defecation

    Source(s): Handouts
  • 1 decade ago

    中文 消化系統的主要功能是消化食物,吸收營養,排出消化吸收後的食物殘渣,人體的消化系統主要由消化道和消化腺組成。

    消化道包括口腔、咽、食管、胃、小腸、大腸、肛管、組成

    消化腺又分為小消化腺和大消化腺兩種。

    小消化腺是散在於消化管各部的管壁內的小腺體。這類腺體數量甚多,如胃腺、腸腺等:

    大消化腺位於消化道外,它們主要通過導管淨分泌物排入消化管內。大消化腺主要有:三對唾液腺(腮腺、下頜下腺、舌下腺)、肝臟和胰臟。

    消化系統是一個與生物相關的小作品。你可以通過編輯或修訂擴充其內容。

    消化系統

    人體:口腔 - 咽 - 食道 - 胃 - 胰腺 - 膽囊 - 肝 - 小腸(十二指腸、空腸、迴腸) - 盲腸 - 結腸 - 直腸 - 肛門

    其他動物:嗉囊

    英文

    Salivary Glands

    The mouth contains the salivary glands which are accessory digestive glands that produce a fluid secretion called saliva.

    The Tooth

    The tooth can be broken down by acids produced by the mouth for digestive purposes. This process is called "decay". To prevent decay, good oral hygiene, consisting of daily brushing and flossing, is necessary.

    The Eso*****us

    The eso*****us is a muscular tube which carries food and liquids from the throat to the stomach for digestion after it has been chewed and chemically softened in the mouth.

    Stomach

    The stomach consists of layers of muscle and nerves that continue the breakdown of food which begins in the mouth.The stomach has several functions: (1) as a storage bin, holding a meal in the upper portion and releasing it a little at a time into the lower portion for processing; (2) as a food mixer, the strong muscles contract and mash the food into a sticky, slushy mass; (3) as a sterilizing system, where the cells in the stomach produce an acid which kills germs in "bad" food; (4) as a digestive tub, the stomach produces digestive fluid which splits and cracks the chemicals in food to be distributed as fuel for the body.

    Liver

    The liver cleanses the blood and processes nutritional molecules, which are distributed to the tissues. When we eat, more blood is diverted to the intestines to deal with digestive processes; when not eating, three-fourths of the blood supply to the liver comes from the intestines.

    Spleen

    The spleen is the largest of the lymphoid tissues. It is a valuable organ which produces some of the white blood cells, filters the blood, destroys old, worn-out red blood cells and returns needed iron to the blood, disposing of the rest as waste. The spleen also stores excess blood for emergencies; for example, when oxygen in the circulatory system is short.

    Small Intestine

    It is divided into three sections: (1) the duodenum, a receiving area for chemicals and partially digested food from the stomach; (2) the jejunum, where most of the nutrients are absorbed into the blood and (3) the ileum, where the remaining nutrients are absorbed before moving into the large intestine. The intestines process about 2.5 gallons of food, liquids and bodily waste every day. The small intestine also makes waves which move the food forward, but these are usually weak and infrequent to allow the food to stay in one place until the nutrients can be absorbed. If a toxic substance enters the small intestine, these movements may be strong and rapid to expel the poisons quickly.

    Large Intestine

    The large intestine, or colon, consists of ascending, transverse, descending, and sigmoid portions. Substances which have not been absorbed in the small intestine enter the large intestine in the form of liquid and fiber. The large intestine or "bowel" is sometimes called the "garbage dump" of the body, because the materials that reach it are of very small use to the body and are sent on to be disposed of. The first half of the colon absorbs fluids and recycles them into the blood stream. The second half compacts the wastes into feces, secretes mucus which binds the substances, and lubricates it to protect the colon and ease its passage.

    Rectum

    The rectum is a short, muscular tube that forms the lowest portion of the large intestine and connects it to the anus. Feces collects here until pressure on the rectal walls cause nerve impulses to pass to the brain, which then sends messages to the voluntary muscles in the anus to relax, permitting expulsion.

Still have questions? Get your answers by asking now.