Exocytosis

I'll help you now! Cellnosuke!

I almost vanished from this site, I did.

You're too naive, Cellnosuke!

How were you planning to get that stuck onigiri out of your throat?

I said it before, but you don't have a mouth, do you?

So, in today's lecture, we'll learn how cells without mouths release substances outside the body.

Listen carefully!

Today's lecture is about exocytosis.

Do you remember from the previous lecture when we talked about cells taking in large substances by engulfing them through the cell membrane?

And this is called endocytosis. Is that clear so far?

Well, that's fine. Let's proceed with the explanation now.

The exocytosis we'll learn today is the opposite of that.

It's the process of releasing large substances like proteins from inside the cell to the outside.

Can you imagine it a little bit?

Don't worry, by the end of today's lecture, you'll have a clearer image of it.

Now, let's explain in detail how substances are released outside the cell through exocytosis.

In exocytosis, the substances to be released outside the cell first move to the cell membrane enclosed in vesicles.

Next, the cell membrane and the vesicle fuse together.

Finally, the fused vesicle opens toward the outside of the cell, allowing the substances to be released into the extracellular space.

To summarize, the process is as follows.

That's right, isn't it?

First of all, it's enough if you understand that exocytosis is the process for releasing substances outside the cell.

That's a good question.

It's about when exocytosis is used and in what circumstances.

Hormones, you know.

Exactly. One of the purposes of exocytosis is to release hormones produced inside the cell to the outside.

It might get complicated, so we won't go into the details of hormones here, but...

Think of hormones as substances that can give commands to other cells.

When I send a hormone with the command "run" to Cellnosuke, it starts running.

You can think of it as orders from a boss, for now.

Some of these hormones are produced inside the cell using proteins.

And as a reminder, proteins are large substances that cannot pass through the small pores in the cell membrane.

Therefore, they need another way to send the hormones they produce outside the cell.

That's where exocytosis comes in.

That's good to hear.

This concludes today's lecture.

As explained in the previous lecture, endocytosis is a form of active transport that uses energy (ATP) to transport substances.

Exocytosis is also a form of active transport, similarly utilizing energy (ATP) for transportation.

These two processes are often tested, so make sure to remember them well.

That concludes today's lecture.

Lastly, let's solve a question.