that goes from our mouths to our anuses called the alimentary canal or sometimes the gastrointestinal

消化道

tract. This tube starts and ends outside of your body, and it's how you process and

道。這條管子的起點和終點都在你的身體之外，它是你處理和處理的方式

extract nutrients and materials from the food you eat. But it's also a spot for potential

從你所吃的食物中提取營養和材料。但它也是一個潛在的點

pathogens to sneak in. Our digestive system interfaces with all kinds of nasty germs,

病原體潛入。我們的消化系統與各種討厭的病菌有接口。

and as a result, it's armed with multiple immune system resources to protect our insides

是以，它配備了多種免疫系統資源來保護我們的內臟

from the outside. So today, we're taking a tour of the alimentary canal with a focus on immunity.

從外面看所以今天，我們要帶大家參觀一下消化道，重點是免疫力。

Digestion itself is a long process and involves everything from mechanically

消化本身是一個漫長的過程，涉及到從機械上的消化，再到機械上的消化。

grinding down food in our mouths to treating food with enzymes so that we can better absorb nutrients.

把食物在嘴裡磨碎，到用酶處理食物，讓我們更好地吸收營養。

Therefore, there isn't just one immune system checkpoint — there

是以，並不是只有一個免疫系統檢查點--有

are safeguards along the entire system. Like the saliva in our mouths is really good at

是沿著整個系統的保障。就像我們嘴裡的唾液，真的很擅長於。

starting carbohydrate digestion, but molecular components in saliva can also act as a first

開始碳水化合物的消化，但唾液中的分子成分也可以作為第一道工序。

layer of defense against pathogens. For instance, an enzyme in our saliva called lysozyme can

對抗病原體的一層防禦。例如，我們唾液中的一種叫做溶菌酶的酶，可以做到

slice open bacteria cells, and there are antimicrobial peptides like histatins that can inhibit the

切開細菌細胞，有組織蛋白等抗菌肽，可以抑制。

growth of certain fungi. And some of those salivary glands have cells that make an antibody

某些真菌的生長。而其中一些唾液腺的細胞能產生一種抗體。

called immunoglobulin A which provides protection to the cells coating the mouth. But as we

稱為免疫球蛋白A，它為口腔塗層細胞提供保護。但是，當我們

get closer to the organs that absorb nutrients into our bloodstream, we need more sophisticated

我們需要更先進的技術，以便更接近吸收血液中營養的器官。

safeguards in place. The first thing your food sees before being swallowed are the tonsils

保障措施到位。食物在被吞嚥之前，首先看到的是扁桃體。

— bits of lymphatic tissue that provide a little more protection. While we might not

- 淋巴組織的位，提供更多的保護。雖然我們可能不會

care about them unless they get inflamed and we need them removed, they create an immune

除非他們發炎，我們需要去除他們，他們創造一個免疫的

checkpoint between the mouth and the throat. After we swallow this chewed up chunk of food,

口腔和喉嚨之間的檢查點。當我們吞下這塊嚼碎的食物後。

it goes down the esophagus — just a tube that transports that bolus of food from the

它進入食道 - 只是一個管子，從食道運送食物栓。

mouth to the stomach. And the stomach itself is a major contributor to chemical digestion,

口到胃。而胃本身就是化學消化的主要貢獻者。

allowing us to create enzymes like pepsin to break down peptide bonds in proteins. But

讓我們能夠創造出像胃蛋白酶這樣的酶來分解蛋白質中的肽鍵。但是

it also keeps us safe from ingested pathogens. The stomach is coated in glands called oxyntic

它還能讓我們免受攝入的病原體的傷害。胃部塗有稱為 "氧合 "的腺體。

glands which include cells called parietal cells that secrete gastric juice. Gastric

腺體，其中包括被稱為頂葉細胞的細胞，可分泌胃汁。胃

juice is highly acidic, with a pH anywhere from 1 to 3.0. It's made up mostly of hydrochloric

汁是高度酸性的，pH值在1到3.0之間。它的主要成分是鹽酸

acid, which you might've experimented with in chemistry class. This creates a hostile

酸，你可能在化學課上做過實驗。這樣就會產生一種敵對的

environment that many microorganisms wouldn't be able to survive in. As we continue down

許多微生物無法生存的環境。當我們繼續往下走

the canal, we see a bunch of defenses once we get into the small intestine. It is, after

甬道，一旦進入小腸，我們就會看到一堆的防線。它是，後

all, where a lot of nutrient absorption happens during digestion. And if we're absorbing

所有，其中很多營養物質的吸收發生在消化過程中。如果我們吸收

anything into the bloodstream or lymphatic system, we need to make sure it's not going

血液或淋巴系統中的任何東西，我們需要確保它不去

to hurt us. So it's coated in a single layer of cells called the intestinal epithelium

來傷害我們。所以它被塗上了一層單層的細胞，叫做腸上皮細胞

which creates a barrier against microbes. Some of these epithelial cells secrete mucins

這就形成了一道抵禦微生物的屏障。其中一些上皮細胞會分泌粘液素。

that keep microbes out of the more sensitive epithelium — kind of like a sticky fly trap.

阻止微生物進入更敏感的上皮層--有點像一個粘性的捕蠅器。

Others act like alarm systems that release chemical messengers when they detect a pathogen

其他的就像警報系統一樣，當它們檢測到病原體時，會釋放化學信使。

and recruit white blood cells to the scene. Then there are a bunch of little lymphatic

並招募白血球到現場。還有一堆小淋巴管

tissue buds scattered around the intestine that we call, appropriately, gut-associated

散佈在腸道周圍的組織芽，我們恰當地稱之為腸道相關的

lymphoid tissue, or GALT. But we also have trillions of good microbes in our intestines

淋巴組織，或GALT。但我們的腸道中也有數萬億的好微生物

which you might've heard of referred to as your gut microbiome. It's not the only

你可能聽說過它被稱為你的腸道微生物組。這不是唯一的

colony of non human microbes you have on your body either. You have different microbiomes

你身上的非人類微生物群落也。你有不同的微生物組

on your tongue and mouth, on your skin or vagina. And among the many digestive jobs

在你的舌頭和嘴上，在你的皮膚或陰道上。在眾多的消化系統工作中

the gut microbiome has, it helps us defend against pathogens by competing for space and

腸道微生物組有，它幫助我們抵禦病原體，通過競爭空間和。

nutrients and also secreting substances that are toxic to those pathogens. Plus, they can

營養物質，還能分泌出對這些病原體有毒性的物質。另外，它們還可以

trigger our innate immune response, a generalized, first pass of immune responses, when they

觸發我們的先天性免疫反應，這是免疫反應的一個普遍性的第一關，當他們

detect potential infection and to help kick start our immune systems when we're born.

檢測潛在的感染，並在我們出生時幫助啟動我們的免疫系統。

These gut microbes are present all throughout your gut, and pop up again when we move into

這些腸道微生物存在於你的整個腸道中，當我們進入了

the next portion of our GI tract, a chamber called the cecum, which features a little

我們腸胃道的下一個部分，一個叫做盲腸的腔室，它的特點是有一個小的盲腸。

dangly organ, the appendix. In recent years, researchers have gotten rid of the idea that

dangly器官，闌尾。近年來，研究人員已經擺脫了這樣的想法，即

the appendix is a useless remnant of evolution and started to understand its role in immunity.

闌尾是進化過程中無用的遺留物，開始瞭解它在免疫中的作用。

The inner layers of the appendix are home to all kinds of immune cells like B and T

闌尾的內層是各種免疫細胞如B、T等的家。

cells, along with natural killer cells. Plus, it houses a reservoir of those good bacteria

細胞，以及自然殺手細胞。另外，它還儲存著那些好的細菌。

that can replenish your normal gut microbiome in cases where the colon needs more like after

可以補充你正常的腸道微生物組，在結腸需要更多的像後

diarrhea. Our large intestines, or colons, have similar immune defenses as our small

腹瀉。我們的大腸或結腸，與我們的小腸有類似的免疫防禦系統。

intestine — more lymph tissue and a slightly different makeup of gut microbes.

腸道--更多的淋巴組織和腸道微生物的構成略有不同。

And those differences are due to how the large intestine

而這些差異是由於大腸的方式。

doesn't absorb nutrients into the bloodstream like the small intestine does. By the end

並不像小腸那樣將營養物質吸收到血液中。到最後

of the alimentary canal, your gut and immune system will hopefully have kept you safe from

您的腸道和免疫系統有望使您免受消化道疾病的影響。

all kinds of potential ingested pathogens. Thanks for watching this episode of Seeker Human.

各種潛在的攝取病原體。感謝收看本期《探索者人類》。

If you want to learn more about the history of the immune system, check out this video

如果你想了解更多關於免疫系統的歷史，請看這個視頻。

we made a few months ago. Otherwise, make sure you're subscribed so you don't miss

我們幾個月前做的。否則，請確保您已訂閱，這樣您就不會錯過以下內容

any future uploads from us.

我們今後的任何上傳。