人體的奧秘 - 你身體入面個碌腸

目錄

(1)基本既心臟介紹
lihkg.com/thread/649350

(2)基本既肺部介紹
lihkg.com/thread/652225

(3)基本既腎臟介紹
lihkg.com/thread/665504

(4)基本既胃部介紹
lihkg.com/thread/673704

建議由第一期開始慢慢睇
想睇最新目錄請自行起底去最新個post
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The next digestive organ is the small intestine. 

下一個要講既消化器官係小腸 (small intestine)。

I can't think of a metaphor for small intestine, haha. But, the two main jobs of small intestine are digestion and absorption. 

我真心唸唔到小腸可以比喻D咩，有高手唸到既可以同我講下。但，要講小腸既功能既話，佢主要係用黎做兩樣野，分別係消化 (digestion) 同 吸收 (absorption)。終於可以開始吸收食物。

Let's find out how small intestine work. 

所以一起黎睇下小腸點運作啦。

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Small intestine can be divided into 3 main parts, the duodenum, the jejunum and the ileum. 

小腸主要可以分做3個部份，十二指腸 (duodenum) 、空腸 (jejunum) 同埋迴腸 (ileum)。

Duodenum, the first section of the small intestine connected to the stomach. It is mainly responsible for the digestion. The desending part of the duodenum has a small opening called the major duodenum papilla. It is an opening for the bile and pancreatic enzymes. 

十二指腸係小腸既第一部份，連接住個胃。十二指腸既主要功能係消化，當然都有吸收，不過相對消化而言小好多。十二指腸下降既部份有一個細細地既窿，叫做十二指腸大乳頭 (major duodenum papilla) ，笑左。此乳頭非彼乳頭，十二指腸大乳頭唔係噴奶水，而係噴膽汁 (bile) 同埋胰臟酶 (pancreatic enzymes)。

Jejunum, the second section of the small intestine. It is mainly responsible for the absorption. 

空腸係小腸既第二部份，主要負責吸收，同樣啦，相對消化而言。

Ileum, the last section of the small intestine connected to the colon. It is responsible for cleaning up the rest. 

迴腸係小腸既最後一個部份，連接住條大腸 (colon) 。佢主要係用黎汁手尾，不厭其煩再講句，相對十二指腸同空腸既功能而言。

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The exocrine glands in small intestine is called the intestinal glands. There is another old name called crypts of Lieberkühn. Located inbetween the wall of small intestine. 

其中一種小腸既外分泌腺叫小腸腺 (intestinal glands)。位於小腸壁既中間。

(From The Human Protein Atlas)

The intestinal glands have different types of cells with different secretion, including anti-microbial substances and mucosa. Surprisingly, the intestinal glands are not the major source of digestive enzymes. 

小腸腺又有唔同既細胞負責分泌唔同既野，包括抗菌物質同埋粘膜。神奇既係，小腸腺唔係點分泌消化酶，或者係因為個胰臟太勁，搶曬D野黎做

The figure shows another glands called the Bruuner's glands, it secretes bicarbonate rich mucous substances in order to neutralize the acidic chyme. Brunner's glands are mainly exist in duodenum so it is also called duodenal glands. 

張圖比埋小腸既另一隻腺，叫做十二指腸腺 (Bruuner's glands / duodenal glands)，主要係用黎分泌含豐富碳酸氫離子 (bicarbonate, 中文名真係幾鳩下) 既粘膜去中和酸性食糜。

# Some details in cells in intestinal glands
    (i)Paneth cell - seretion of anti-microbial substances
    (ii)Goblet cell - seretion of mucosa #

# 識多小小「小腸腺」細胞
   (壹)潘氏細胞 - 分泌抗菌物質
   (貳)杯狀細胞 - 分泌粘膜 #
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A very unique structure called the brush border can be found on the inner epithilium of the small intestine. 

小腸內壁既上皮組織有一樣好特別既結構，叫做刷狀緣 (brush border)。

This figure shows the strcuture of the brush border. Micovilli can be found on villi and villi can be found on circular folds. There are many circular folds on the inner epithilium of the small intestine. Brush borders help to increase the surface area of the inner small intestine. 

張圖解釋番刷狀緣既結構。小腸內壁既上皮組織本來就唔平整，有大大小小既環狀摺 (circular folds) ，而依D環狀摺上面而有好多絨毛(villus)，再睇入D會發現呢D絨毛上面重有微絨毛 (microvillus)。(再近D就可以睇到組成微絨毛既細胞) 依D刷狀緣大大咁增加左小腸內壁既面積，令吸收同消化更有效率。

Cells that lining on these brush borders are mainly enterocyte, most abundant cells in small intestine that responsible for absorption. 

組成刷狀緣既上皮組織主要係腸上皮細胞，係小腸入面最主要既細胞，負責吸收作用。

Digestive enzymes like enterokinase and lactase can be found on the brush boarder cell's membrane. These enzymes are called brush border enzymes, produced by intestinal epithelial cells

係刷狀緣上面會有好多刷狀緣酶 (brush border enzymes)，例如：腸激活酶 (enterokinase)、乳糖酶 (lactase)，佢地由小腸上皮組織既細胞制造。

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The chyme's point of view. 

用食糜既角度睇小腸既消化同吸收作用。

(1) The chyme is squirted into the duodenum by the stomach. 

(2) The chyme is delivered by peristalsis. 

(3) The bile and the pancreatic enzymes are secreted into the duodenum through the major duodenum papilla. 

(4) Before going into the jejunum, most of the chyme is digested into simple molecules and ready to be absorbed. 

(一) 食糜由胃慢慢咁噴入去十二指腸。

(二) 食糜透過腸既蠕動 (peristalsis) 移動。(補充番，食道都係用蠕動既方式運送食團)

(三) 膽汁同胰消化酶由十二指腸大乳頭進入十二指腸。

(四) 食糜被消化成基本既分子，可以準備進入空腸作進一步被吸收。


# Some details in the bile

Bile is a kind of fluid produced by the liver and the bile salt inside acts like a detergent to lower the surface tension of lipid compounds so that they can be easier to be broken down and digest. This process is called emulsification. #

# 識多小小膽汁

膽汁係由肝製造，裡面既膽鹽好似番梘咁，可以令到脂類既表面張力降低從而令到脂類容易D被分解消化，依個過程叫做乳化作用 ( emulsification)。#


# Some details in the pancreatic enzymes

The pancreatic enzymes are the major parts of the digestion. They are the strongest enzymes throughout the whole digestive process. The pancreatic enzymes include several enzymes. 

    (i) Trypsinogen - activated by enterokinase, a kind of brush border enzyme. The activated form of trypsinogen is called trypsin. It is an enzyme of protein lysis. 

    (ii) Chymotrypsinogen - activated by trypsin. The activated form of chymotrypsinogen is called chymotrypsin. It is an enzyme of protein lysis. (Targeted to different protein compared with trypsin)

    (iii) Pancreatic amylase - an enzyme of polysaccharides lysis. 

    (iv) Pancreatic lipase - an enzyme of lipids lysis. #

# 識多小小胰消化酶

胰消化酶係成個消化作用中最主要既部份，代表住胰消化酶係消化系統中最具破壞性既酶。胰消化酶主要可以分做以下幾種。

    (壹) 胰蛋白酶原 - 由腸激活酶激活，激活左之後叫胰蛋白酶，用黎分解蛋白質。 

    (貳) 胰凝乳蛋白酶原 - 由胰蛋白酶激活，激活左之後叫胰凝乳蛋白酶，都係用黎分解蛋白質。

    (參) 胰澱粉酶 - 用黎分解多醣。

    (肆) 胰脂肪酶 - 用黎分脂類。#

(5) Simple molecules are being further absorbed by the enterocytes in jejunum and delivered into the blood stream or lymphatic capillaries. 

(6) After entering the ileum, the remaining simple molecule, vitamins and the bile are then absorbed. 

(五) D基本分子係空腸被腸上皮細胞進一步吸收，再送入血管或者淋巴管。

(六) 淨低既基本分子到左迴腸再進一步吸收，係迴腸重有維生素 (vitamin) 同埋膽汁既吸收。


# Some details in absorption

The simple molecules are in 4 forms, amino acid, monosaccharide, nucleic acids and triglyceride. 

    (i) Amino acid - units of proteins, diffused into blood stream through primary active transport. 

    (ii) Monosaccharide - units of carbohydrates, diffused into blood stream through secondary active transport. 

    (iii) Nucleic acids - units of deoxyribonucleic acid (DNA), diffused into blood stream through primary active transport , as well as the nucleobase. 

    (iv) Triglyceride (glcerol and the fatty tails) - units of lipids, diffused into lacteal (lymphatic capillaries) in the form of chylomicron. #

# 識多小小吸收作用

基本分子可以分做4種，分別係胺基酸、單糖、核酸同埋甘油三脂。

    (壹) 胺基酸 - 蛋白質既組成分子，以一級主動運輸進入血管。 

    (貳) 單糖 -  醣類既組成分子，以二級主動運輸進入血管。

    (參) 核酸 - 基因既組成分子，連同核鹼基以一級主動運輸進入血管。

    (肆) 甘油三脂 (甘油同三條脂類尾巴) - 脂類既組成分子，會首先係腸上皮細胞入面包裝成乳糜微粒 (chylomicron)，一種脂蛋白  (lipoprotein)，再滲透入去乳糜管 (lacteal)，一種淋巴管。 #


(7) The remaining chyme finally being delivered into the colon, through the ileocecal valve. 

(七) 最後最後有幸淨低既食糜就要由迴盲瓣 (ileocecal valve) 進入大腸啦。

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The food digestion is still processing. To be continued in the colon. 

食物消化重進行緊，密切留意發展。

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