WEBVTT
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Imagine somebody builds a radio tower powerful enough to broadcast across an entire city.
00:01:05.679 --> 00:01:11.759
The signal is everywhere, in houses, cars, restaurants, and in hospitals.
00:01:12.000 --> 00:01:14.959
But that doesn't mean everybody hears the music.
00:01:15.280 --> 00:01:20.959
You need a radio, and that radio needs to be able to tune into the right frequency.
00:01:21.280 --> 00:01:23.759
Your cells have a similar problem.
00:01:24.560 --> 00:01:35.519
Hormones can travel through your circulation and reach enormous numbers of cells, but a cell generally needs the appropriate receptor to respond to that particular signal.
00:01:35.919 --> 00:01:39.439
Think of the receptor as part of the cell's listening equipment.
00:01:39.680 --> 00:01:40.960
A hormone arrives.
00:01:41.120 --> 00:01:46.560
If the appropriate receptor is there, the cell can recognize the message and respond.
00:01:46.960 --> 00:01:51.599
If it isn't, that particular message may essentially pass by.
00:01:52.159 --> 00:01:58.640
This is one reason different tissues can behave differently even though they're sitting in the same bloodstream.
00:01:58.879 --> 00:02:03.439
And receptors aren't just being passive name tags.
00:02:03.920 --> 00:02:10.480
When the right molecule interacts with its receptor, the receptor can change what happens inside the cell.
00:02:10.800 --> 00:02:13.759
Enzymes, for example, can become more or less active.
00:02:14.000 --> 00:02:21.840
Transporters can move, genes can change their activity, fuel use can change, same thing with growth and repair.
00:02:22.240 --> 00:02:28.159
A cell can completely alter what it's doing because it's received one particular message.
00:02:28.319 --> 00:02:31.360
And we're going to see this over and over again.
00:02:31.680 --> 00:02:41.920
Insulin has receptors, thyroid hormones have receptors, cortisol, estrogen, any type of hormone you can think of, they all have receptors.
00:02:42.159 --> 00:02:47.840
And when we eventually get into cancer, receptors become enormously important there too.
00:02:48.079 --> 00:02:50.480
But now we've created another problem.
00:02:51.680 --> 00:02:57.199
Because some signaling molecules bind to receptors at the surface of the cell.
00:02:57.439 --> 00:02:59.280
The message is outside.
00:02:59.519 --> 00:03:01.680
The response happens inside.
00:03:02.079 --> 00:03:03.439
So, how?
00:03:04.639 --> 00:03:08.000
Imagine someone walks up to your house and presses the doorbell.
00:03:08.240 --> 00:03:12.319
The person remains outside, but something happens inside the house.
00:03:12.479 --> 00:03:16.400
You hear the doorbell, you stand up, you walk towards the door.
00:03:16.639 --> 00:03:21.039
One event outside created a chain of events inside.
00:03:21.359 --> 00:03:28.719
Cells do something much more sophisticated, and that little biological doorbell is where we're going next.
00:00:58.960 --> 00:01:05.439
Imagine somebody builds a radio tower powerful enough to broadcast across an entire city.
00:01:05.679 --> 00:01:11.759
The signal is everywhere, in houses, cars, restaurants, and in hospitals.
00:01:12.000 --> 00:01:14.959
But that doesn't mean everybody hears the music.
00:01:15.280 --> 00:01:20.959
You need a radio, and that radio needs to be able to tune into the right frequency.
00:01:21.280 --> 00:01:23.759
Your cells have a similar problem.
00:01:24.560 --> 00:01:35.519
Hormones can travel through your circulation and reach enormous numbers of cells, but a cell generally needs the appropriate receptor to respond to that particular signal.
00:01:35.919 --> 00:01:39.439
Think of the receptor as part of the cell's listening equipment.
00:01:39.680 --> 00:01:40.960
A hormone arrives.
00:01:41.120 --> 00:01:46.560
If the appropriate receptor is there, the cell can recognize the message and respond.
00:01:46.960 --> 00:01:51.599
If it isn't, that particular message may essentially pass by.
00:01:52.159 --> 00:01:58.640
This is one reason different tissues can behave differently even though they're sitting in the same bloodstream.
00:01:58.879 --> 00:02:03.439
And receptors aren't just being passive name tags.
00:02:03.920 --> 00:02:10.480
When the right molecule interacts with its receptor, the receptor can change what happens inside the cell.
00:02:10.800 --> 00:02:13.759
Enzymes, for example, can become more or less active.
00:02:14.000 --> 00:02:21.840
Transporters can move, genes can change their activity, fuel use can change, same thing with growth and repair.
00:02:22.240 --> 00:02:28.159
A cell can completely alter what it's doing because it's received one particular message.
00:02:28.319 --> 00:02:31.360
And we're going to see this over and over again.
00:02:31.680 --> 00:02:41.920
Insulin has receptors, thyroid hormones have receptors, cortisol, estrogen, any type of hormone you can think of, they all have receptors.
00:02:42.159 --> 00:02:47.840
And when we eventually get into cancer, receptors become enormously important there too.
00:02:48.079 --> 00:02:50.480
But now we've created another problem.
00:02:51.680 --> 00:02:57.199
Because some signaling molecules bind to receptors at the surface of the cell.
00:02:57.439 --> 00:02:59.280
The message is outside.
00:02:59.519 --> 00:03:01.680
The response happens inside.
00:03:02.079 --> 00:03:03.439
So, how?
00:03:04.639 --> 00:03:08.000
Imagine someone walks up to your house and presses the doorbell.
00:03:08.240 --> 00:03:12.319
The person remains outside, but something happens inside the house.
00:03:12.479 --> 00:03:16.400
You hear the doorbell, you stand up, you walk towards the door.
00:03:16.639 --> 00:03:21.039
One event outside created a chain of events inside.
00:03:21.359 --> 00:03:28.719
Cells do something much more sophisticated, and that little biological doorbell is where we're going next.
