Name: 大腺--您的內分泌系統。生物學速成班#33 (Great Glands - Your Endocrine System: CrashCourse Biology #33)
Uploaded: 2021-01-14T06:03:59.000Z
Duration: 11 min 21 s
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關係子句

Hormones! Those things that make teenagers moody and miserable,

and they cause growth spurts and acne, and they can make

a perfectly normal student totally obsessed with his algebra teacher.

boots-on-the-ground experience with that last one.

But all that mayhem is just the handiwork of your sex hormones.

The fact is that there are more than 50 different kinds

of hormones coursing through you right now,

and all multicellular organisms produce one kind or another.

For instance, hormones regulate the process of metamorphosis

in insects, and they're what stimulate plants to grow

In animals, the network that makes and releases hormones,

your endocrine system, is one of the two ways,

along with the nervous system, that important information

is communicated from one part of your body to another.

Right now, your endocrine system is spraying hormones

into your bloodstream that are doing all kinds of things

all over your body: giving instructions to other glands,

regulating the levels of salt, sugar and water in your blood,

and, yes, they're partly responsible for that daydream

you may or may not be having about Taylor Lautner right now.

The endocrine system and the nervous systems both carry

information around the body, but while the nervous system

carries information really quickly and the responses

are usually short-lived, endocrine responses take a while

to get going, but their effects can last for hours or even weeks.

The word hormone comes from the Greek for "to arouse activity,"

and they're secreted by endocrine glands,

the series of organs that also manufacture them.

In addition to endocrine glands, you also have exocrine glands

and as you can tell by the name, they send stuff outside the body,

And your glands are all over the freakin' place:

Some of the heaviest hitters are in your brain,

but you also have them in your throat, right over your kidneys,

right below your stomach, and of course in your baby-making areas.

All glands have blood vessels coming from them so that hormones

that they release can get into the bloodstream fast.

And many of your hormones circulate through your whole body,

only binding to the cells that have the right

But there are some hormone-driven messaging systems

For instance, paracrine signaling releases hormone molecules

that degrade really quickly and are only received

Example: testosterone, manufactured by the testes, tells the testes

how many sperm they need to be making right this second.

And to see hormones work on an even smaller scale,

which sends chemical messages within a cell,

or from one cell to the adjacent cell, at most.

This is what happens in your immune system when a single T-cell

realizes it needs to start cloning itself

Your cells receive hormones through signal receptors,

but how and where a hormone binds to its receptor

There are three different types: steroids, which do a lot more

than make your muscles big and get you all angry and stuff.

and there's a bunch of different types of them.

There are peptides, which are just chains of amino acids.

And monoamines, which are based on a single amino acid.

The only really important thing we need to keep straight about these

is that peptide and amine hormones are water-soluble

And since cell membranes are made of lipids,

But steroids are lipid-soluble, so they're able to penetrate

the membrane and bind with receptors in the cell's nucleus.

Using these methods, the endocrine system sends out all kinds

of important chemical bulletins, many of which start up in the brain,

The pituitary gland, it's the master gland,

Except that Napoleon actually wasn't very small, that's a myth,

The pituitary gland makes hormones that instruct

and those hormones actually get the real leg work done.

The pituitary is connected to the hypothalamus,

the part of the brain that acts as a liaison

between the nervous system and the endocrine system.

So a big part of its job is to tell your glands what to do based on

information it gets from your senses and other nerve functions.

For example, breastfeeding women will start releasing milk

Sensory information, in this case auditory,

comes to the hypothalamus from the nervous system telling it

that there's a little snuggle of baby nearby that might be hungry.