humans eat on average between one and 2.7 kilograms of food a day.

平均每天都會吃下大約 1-2.7 公斤的食物

That's over 365 kilograms a year per person,

那就代表每個人每年就吃了超過 365 公斤

and more than 28,800 kilograms over the course of a lifetime.

而換算下來一輩子吃的食物量就超過了 28,800 公斤

And every last scrap makes its way through the digestive system.

每一片食物的小碎屑都會通過我們的消化系統

Comprised of ten organs covering nine meters,

消化系統由 10 個器官組成、總長 9 公尺

and containing over 20 specialized cell types,

且有超過 20 種專門的細胞

this is one of the most diverse and complicated systems in the human body.

是人體最多樣、最複雜的系統之一

Its parts continuously work in unison to fulfill a singular task:

各個器官齊心協力完成一項特別的任務：

transforming the raw materials of your food

將我們吃下肚的食物轉換成

into the nutrients and energy that keep you alive.

我們生活所需的營養及能量

Spanning the entire length of your torso,

範圍跨越整個軀幹的消化系統

the digestive system has four main components.

由四個主要部分組成

First, there's the gastrointestinal tract,

第一個是我們的胃腸道

a twisting channel that transports your food

它是個用來運送食物的扭曲通道

and has an internal surface area of between 30 and 40 square meters,

內部的表面積大約介在 30-40 平方公尺

enough to cover half a badminton court.

足以覆蓋半個羽毛球場

Second, there's the pancreas, gallbladder, and liver,

第二個是胰臟、膽囊和肝臟

a trio of organs that break down food using an array of special juices.

這三個器官會先後分泌一系列的消化液來分解食物

Third, the body's enzymes, hormones, nerves, and blood.

第三部分則是酶、激素、神經及血液

all work together to break down food,

協同分解食物

modulate the digestive process,

調節消化過程

and deliver its final products.

並運送最後分解的產物

Finally, there's the mesentery,

最後是腸繋膜

a large stretch of tissue that supports

它是一大塊用來支撐

and positions all your digestive organs in the abdomen,

及固定腹中消化器官的組織

enabling them to do their jobs.

讓器官們得以各司其職

The digestive process begins before food even hits your tongue.

在食物進到你的嘴裡前，消化過程早就開始運作了

Anticipating a tasty morsel, glands in your mouth start to pump out saliva.

一偵測到美味的食物，你口中的腺體就會開始分泌唾液

We produce about 1.5 liters of this liquid each day.

我們每天都會分泌大約 1.5 公升的口水

Once inside your mouth,

只要食物一進到你的嘴裡

chewing combines with the sloshing saliva

唾液在咀嚼的過程中就會

to turn food into a moist lump called the bolus.

將食物變成潮濕的塊狀物，稱為食團

Enzymes present in the saliva break down any starch.

唾液中的酵素會分解所有澱粉

Then, your food finds itself at the rim of a 25-centimeter-long tube called the esophagus,

接著，這些食團就會被送至一個 25 公分長的管邊，我們稱之為食道

down which it must plunge to reach the stomach.

而再往下食團就會掉入胃

Nerves in the surrounding esophageal tissue

在食道組織周圍的神經

sense the bolus's presence and trigger peristalsis,

感覺到食團的存在並引發蠕動

a series of defined muscular contractions.

也就是一連串的肌肉收縮

That propels the food into the stomach, where it's left

這個機制可以將食物推進胃裡

at the mercy of the muscular stomach walls, which bound the bolus, breaking it into chunks.

任由胃壁的肌肉將食團分成小塊

Hormones, secreted by cells in the lining,

內膜細胞分泌的激素引發胃壁

trigger the release of acids and enzyme-rich juices from the stomach wall

釋放胃酸和充滿酵素的液體

that start to dissolve the food and break down its proteins.

以開始分解食物及蛋白質

These hormones also alert the pancreas, liver, and gallbladder to produce digestive juices

這些激素同時提醒胰臟、肝臟及膽囊分泌消化液

and transfer bile, a yellowish-green liquid that digests fat, in preparation for the next stage.

並運送分解脂肪的黃綠色膽汁，為下個階段做足準備

After three hours inside the stomach,

在胃裡停留三個小時後

the once shapely bolus is now a frothy liquid called chyme,

那些有形的食團已變成帶有泡泡的液狀物體 - 食糜

and it's ready to move into the small intestine.

並準備好被送往小腸

The liver sends bile to the gallbladder

肝臟將膽汁輸送到膽囊

and secretes it into the first portion of the small intestine called the duodenum.

並將其分泌至小腸的第一部分 - 十二指腸

Here, it dissolves the fats floating in the slurry of chyme, so they can be easily

在這個階段，膽汁先將漂浮在食糜上的脂肪溶解

digested by the pancreatic and intestinal juices that have leached onto the scene.

接著他們就可以輕鬆被淋過的胰液及腸液消化

These enzyme-rich juices break the fat molecules down into

這些充滿酵素的消化液將脂肪分子分解成

fatty acids and glycerol for easier absorption into the body.

脂肪酸和甘油，使其能夠更容易被人體吸收

The enzymes also carry out the final deconstruction of

酵素同時也執行最後一個階段的解構

proteins into amino acids and carbohydrates into glucose.

也就是將蛋白質分解成胺基酸，及將碳水化合物分解成葡萄糖

This happens in the small intestine's lower regions, the jejunum and ileum,

這個過程會發生在小腸的後半段 - 空腸及迴腸

which are coated in millions of tiny projections called villi.

空腸及迴腸的表面披著幾百萬個微小的突起物，我們稱為絨毛

These create a huge surface area to maximize molecule absorption

這些絨毛所形成的巨大表面積使吸收養分的功能大大增強

and transference into the blood stream.

並可以將養分送至血液

The blood takes them on the final leg of their journey to feed the body's organs and tissues.

在這趟旅程的尾聲，血液將這些養分送至身體的器官和組織

But it's not over quite yet.

但整個過程還沒結束

Leftover fiber, water, and dead cells sloughed off during digestion

殘餘的纖維、水分及在消化過程中脫落的死細胞

make it into the large intestine, also known as the colon.

都會被送往大腸或我們所熟知的結腸

The body drains out most of the remaining fluid through the intestinal wall.

大腸壁會吸收絕大部分的液體

What's left is a soft mass called stool.

而剩下的鬆軟物質就是糞便

The colon squeezes this byproduct into a pouch called the rectum,

結腸將這個副產物擠到直腸這個袋子裡

where nerves sense it expanding

而直腸的神經感覺到膨脹

and tell the body when it's time to expel the waste.

並告訴我們的身體什麼時候該排泄

The byproducts of digestion exit through the anus

消化過程的副產物就會從肛門排出

and the food's long journey, typically lasting between 30 and 40 hours, is finally complete.

在經歷了約 30-40 小時，這趟漫長的食物之旅終於結束了