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Every living being needs to fight off other
living beings that want to feast on them.
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Every living being needs to fight off other
living beings that want to feast on them.
3
00:00:01,175 --> 00:00:06,614
Every living being needs to fight off other
living beings that want to feast on them.
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00:00:06,614 --> 00:00:13,087
So as multicellular life evolved over billions of
years, it came up with ways to defend itself.
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00:00:06,614 --> 00:00:13,087
So as multicellular life evolved over billions of
years, it came up with ways to defend itself.
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00:00:06,614 --> 00:00:13,087
So as multicellular life evolved over billions of
years, it came up with ways to defend itself.
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00:00:13,087 --> 00:00:16,424
Today humans have a sophisticated defense network,
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00:00:13,087 --> 00:00:16,424
Today humans have a sophisticated defense network,
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Today humans have a sophisticated defense network,
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like physical barriers, defense cells, and weapons factories.
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like physical barriers, defense cells, and weapons factories.
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like physical barriers, defense cells, and weapons factories.
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But one of the most important defenses
of our body is largely unknown:
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But one of the most important defenses
of our body is largely unknown:
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But one of the most important defenses
of our body is largely unknown:
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The Complement System
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The Complement System
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The Complement System
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It evolved over 700 million years ago and
is an army of over 30 different proteins
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00:00:27,902 --> 00:00:33,374
It evolved over 700 million years ago and
is an army of over 30 different proteins
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It evolved over 700 million years ago and
is an army of over 30 different proteins
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that work together in a complex
and elegant dance to stop intruders.
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00:00:33,374 --> 00:00:37,878
that work together in a complex
and elegant dance to stop intruders.
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00:00:33,374 --> 00:00:37,878
that work together in a complex
and elegant dance to stop intruders.
25
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All in all, about 15 quintillion of them are saturating
every fluid in your body right now.
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00:00:37,878 --> 00:00:44,251
All in all, about 15 quintillion of them are saturating
every fluid in your body right now.
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All in all, about 15 quintillion of them are saturating
every fluid in your body right now.
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Guided by nothing but chemistry,
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Guided by nothing but chemistry,
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Guided by nothing but chemistry,
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these proteins are one of the most
effective weapons we have against invaders.
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00:00:46,253 --> 00:00:50,691
these proteins are one of the most
effective weapons we have against invaders.
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these proteins are one of the most
effective weapons we have against invaders.
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Many other parts of the immune system are just
tools to activate the Complement System.
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Many other parts of the immune system are just
tools to activate the Complement System.
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Many other parts of the immune system are just
tools to activate the Complement System.
37
00:00:55,863 --> 00:00:58,032
But it's also really dangerous.
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00:00:55,863 --> 00:00:58,032
But it's also really dangerous.
39
00:00:55,863 --> 00:00:58,032
But it's also really dangerous.
40
00:00:58,032 --> 00:01:03,437
Imagine having trillions of little bombs inside
your blood that could go off at any moment.
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00:00:58,032 --> 00:01:03,437
Imagine having trillions of little bombs inside
your blood that could go off at any moment.
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00:00:58,032 --> 00:01:03,437
Imagine having trillions of little bombs inside
your blood that could go off at any moment.
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00:01:03,437 --> 00:01:09,475
So our cells use numerous mechanisms to prevent
complement from accidentally attacking them.
44
00:01:03,437 --> 00:01:09,475
So our cells use numerous mechanisms to prevent
complement from accidentally attacking them.
45
00:01:03,437 --> 00:01:09,475
So our cells use numerous mechanisms to prevent
complement from accidentally attacking them.
46
00:01:10,077 --> 00:01:14,347
Okay, what exactly does it do
and what makes it so dangerous?
47
00:01:10,077 --> 00:01:14,347
Okay, what exactly does it do
and what makes it so dangerous?
48
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Okay, what exactly does it do
and what makes it so dangerous?
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In a nutshell, The Complement System does three things:
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In a nutshell, The Complement System does three things:
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In a nutshell, The Complement System does three things:
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it cripples enemies, it activates the immune system,
and it rips holes in things until they die.
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00:01:27,728 --> 00:01:33,499
it cripples enemies, it activates the immune system,
and it rips holes in things until they die.
54
00:01:27,728 --> 00:01:33,499
it cripples enemies, it activates the immune system,
and it rips holes in things until they die.
55
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But, how?
56
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But, how?
57
00:01:33,934 --> 00:01:35,102
But, how?
58
00:01:35,102 --> 00:01:40,975
After all, these are mindless proteins randomly
drifting around without will or direction.
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00:01:35,102 --> 00:01:40,975
After all, these are mindless proteins randomly
drifting around without will or direction.
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00:01:35,102 --> 00:01:40,975
After all, these are mindless proteins randomly
drifting around without will or direction.
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Well, this is actually part of the strategy.
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Well, this is actually part of the strategy.
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Well, this is actually part of the strategy.
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Complement proteins float around in a sort-of passive mode.
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Complement proteins float around in a sort-of passive mode.
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Complement proteins float around in a sort-of passive mode.
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00:01:47,815 --> 00:01:52,318
They do nothing, until they get activated and change their shape.
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00:01:47,815 --> 00:01:52,318
They do nothing, until they get activated and change their shape.
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00:01:47,815 --> 00:01:52,318
They do nothing, until they get activated and change their shape.
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00:01:52,720 --> 00:01:57,792
In the world of proteins, your shape
determines what you can and cannot do.
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00:01:52,720 --> 00:01:57,792
In the world of proteins, your shape
determines what you can and cannot do.
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00:01:52,720 --> 00:01:57,792
In the world of proteins, your shape
determines what you can and cannot do.
73
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Because shape determines what
you can interact with and in what way.
74
00:01:57,792 --> 00:02:02,530
Because shape determines what
you can interact with and in what way.
75
00:01:57,792 --> 00:02:02,530
Because shape determines what
you can interact with and in what way.
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00:02:02,530 --> 00:02:06,067
For example, in your passive shape you might do nothing.
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00:02:02,530 --> 00:02:06,067
For example, in your passive shape you might do nothing.
78
00:02:02,530 --> 00:02:06,067
For example, in your passive shape you might do nothing.
79
00:02:06,067 --> 00:02:11,072
In your active shape, however, you might, for
example, change the shape of other proteins
80
00:02:06,067 --> 00:02:11,072
In your active shape, however, you might, for
example, change the shape of other proteins
81
00:02:06,067 --> 00:02:11,072
In your active shape, however, you might, for
example, change the shape of other proteins
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activating them so they can activate others.
83
00:02:11,072 --> 00:02:14,107
activating them so they can activate others.
84
00:02:11,072 --> 00:02:14,107
activating them so they can activate others.
85
00:02:14,475 --> 00:02:19,345
Mechanisms like this one can start
cascades that spread very quickly.
86
00:02:14,475 --> 00:02:19,345
Mechanisms like this one can start
cascades that spread very quickly.
87
00:02:14,475 --> 00:02:19,345
Mechanisms like this one can start
cascades that spread very quickly.
88
00:02:19,780 --> 00:02:24,885
Imagine the complement proteins as being like
millions of matches very close together.
89
00:02:19,780 --> 00:02:24,885
Imagine the complement proteins as being like
millions of matches very close together.
90
00:02:19,780 --> 00:02:24,885
Imagine the complement proteins as being like
millions of matches very close together.
91
00:02:24,885 --> 00:02:28,389
Once one catches fire, it ignites the ones around it.
92
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Once one catches fire, it ignites the ones around it.
93
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Once one catches fire, it ignites the ones around it.
94
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They ignite more and suddenly you have a big fire.
95
00:02:28,389 --> 00:02:32,126
They ignite more and suddenly you have a big fire.
96
00:02:28,389 --> 00:02:32,126
They ignite more and suddenly you have a big fire.
97
00:02:32,126 --> 00:02:37,765
To show the actual mechanisms of The Complement
System is a tad complicated and overwhelming.
98
00:02:32,126 --> 00:02:37,765
To show the actual mechanisms of The Complement
System is a tad complicated and overwhelming.
99
00:02:32,126 --> 00:02:37,765
To show the actual mechanisms of The Complement
System is a tad complicated and overwhelming.
100
00:02:37,765 --> 00:02:39,599
So, we'll simplify here.
101
00:02:37,765 --> 00:02:39,599
So, we'll simplify here.
102
00:02:37,765 --> 00:02:39,599
So, we'll simplify here.
103
00:02:39,967 --> 00:02:44,271
Now, let's imagine you cut yourself
and a bunch of bacteria enter the wound
104
00:02:39,967 --> 00:02:44,271
Now, let's imagine you cut yourself
and a bunch of bacteria enter the wound
105
00:02:39,967 --> 00:02:44,271
Now, let's imagine you cut yourself
and a bunch of bacteria enter the wound
106
00:02:44,271 --> 00:02:46,440
and make it into the surrounding tissue.
107
00:02:44,271 --> 00:02:46,440
and make it into the surrounding tissue.
108
00:02:44,271 --> 00:02:46,440
and make it into the surrounding tissue.
109
00:02:46,440 --> 00:02:49,143
Our complement attack begins with C3.
110
00:02:46,440 --> 00:02:49,143
Our complement attack begins with C3.
111
00:02:46,440 --> 00:02:49,143
Our complement attack begins with C3.
112
00:02:49,143 --> 00:02:54,448
C3 is the first match, the initial spark that will start our fire.
113
00:02:49,143 --> 00:02:54,448
C3 is the first match, the initial spark that will start our fire.
114
00:02:49,143 --> 00:02:54,448
C3 is the first match, the initial spark that will start our fire.
115
00:02:54,448 --> 00:02:58,652
And to do that, C3 needs to switch from passive to active.
116
00:02:54,448 --> 00:02:58,652
And to do that, C3 needs to switch from passive to active.
117
00:02:54,448 --> 00:02:58,652
And to do that, C3 needs to switch from passive to active.
118
00:02:58,652 --> 00:03:02,857
How this happens is complex, but
let's just say it can happen randomly
119
00:02:58,652 --> 00:03:02,857
How this happens is complex, but
let's just say it can happen randomly
120
00:02:58,652 --> 00:03:02,857
How this happens is complex, but
let's just say it can happen randomly
121
00:03:02,857 --> 00:03:07,528
through other complement proteins that
bind to enemies or through antibodies.
122
00:03:02,857 --> 00:03:07,528
through other complement proteins that
bind to enemies or through antibodies.
123
00:03:02,857 --> 00:03:07,528
through other complement proteins that
bind to enemies or through antibodies.
124
00:03:07,528 --> 00:03:11,565
All you really need to know is that
C3 breaks into two smaller proteins,
125
00:03:07,528 --> 00:03:11,565
All you really need to know is that
C3 breaks into two smaller proteins,
126
00:03:07,528 --> 00:03:11,565
All you really need to know is that
C3 breaks into two smaller proteins,
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C3a and C3b, that are now activated.
128
00:03:11,565 --> 00:03:15,102
C3a and C3b, that are now activated.
129
00:03:11,565 --> 00:03:15,102
C3a and C3b, that are now activated.
130
00:03:15,102 --> 00:03:22,343
One of these parts, the C3b protein, is like a seeker
missile specialized in bacteria, fungi, and viruses.
131
00:03:15,102 --> 00:03:22,343
One of these parts, the C3b protein, is like a seeker
missile specialized in bacteria, fungi, and viruses.
132
00:03:15,102 --> 00:03:22,343
One of these parts, the C3b protein, is like a seeker
missile specialized in bacteria, fungi, and viruses.
133
00:03:22,343 --> 00:03:27,982
It has a fraction of a second to find a victim
or it will be neutralized by water molecules.
134
00:03:22,343 --> 00:03:27,982
It has a fraction of a second to find a victim
or it will be neutralized by water molecules.
135
00:03:22,343 --> 00:03:27,982
It has a fraction of a second to find a victim
or it will be neutralized by water molecules.
136
00:03:27,982 --> 00:03:34,355
If C3b does find a target, it anchors itself very
tightly to its surface and doesn't let go.
137
00:03:27,982 --> 00:03:34,355
If C3b does find a target, it anchors itself very
tightly to its surface and doesn't let go.
138
00:03:27,982 --> 00:03:34,355
If C3b does find a target, it anchors itself very
tightly to its surface and doesn't let go.
139
00:03:34,355 --> 00:03:37,758
By doing so, the protein changes its shape again.
140
00:03:34,355 --> 00:03:37,758
By doing so, the protein changes its shape again.
141
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By doing so, the protein changes its shape again.
142
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In its new shape, it's now able to grab
other proteins and start a small cascade,
143
00:03:37,758 --> 00:03:42,563
In its new shape, it's now able to grab
other proteins and start a small cascade,
144
00:03:37,758 --> 00:03:42,563
In its new shape, it's now able to grab
other proteins and start a small cascade,
145
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changing its shape multiple times,
adding other complement proteins to itself.
146
00:03:42,563 --> 00:03:47,301
changing its shape multiple times,
adding other complement proteins to itself.
147
00:03:42,563 --> 00:03:47,301
changing its shape multiple times,
adding other complement proteins to itself.
148
00:03:47,301 --> 00:03:53,039
Finally, it transforms itself into a recruiting
platform known as C3 Convertase.
149
00:03:47,301 --> 00:03:53,039
Finally, it transforms itself into a recruiting
platform known as C3 Convertase.
150
00:03:47,301 --> 00:03:53,039
Finally, it transforms itself into a recruiting
platform known as C3 Convertase.
151
00:03:53,507 --> 00:03:59,713
This platform is an expert at activating more
C3 proteins that start the whole cycle anew.
152
00:03:53,507 --> 00:03:59,713
This platform is an expert at activating more
C3 proteins that start the whole cycle anew.
153
00:03:53,507 --> 00:03:59,713
This platform is an expert at activating more
C3 proteins that start the whole cycle anew.
154
00:03:59,713 --> 00:04:02,016
An amplification loop begins.
155
00:03:59,713 --> 00:04:02,016
An amplification loop begins.
156
00:03:59,713 --> 00:04:02,016
An amplification loop begins.
157
00:04:02,016 --> 00:04:05,352
Soon, thousands of proteins cover the bacteria.
158
00:04:02,016 --> 00:04:05,352
Soon, thousands of proteins cover the bacteria.
159
00:04:02,016 --> 00:04:05,352
Soon, thousands of proteins cover the bacteria.
160
00:04:05,352 --> 00:04:07,922
For the bacteria, this is very bad.
161
00:04:05,352 --> 00:04:07,922
For the bacteria, this is very bad.
162
00:04:05,352 --> 00:04:07,922
For the bacteria, this is very bad.
163
00:04:07,922 --> 00:04:11,825
It can cripple the bacteria and make
them helpless, or slow them down.
164
00:04:07,922 --> 00:04:11,825
It can cripple the bacteria and make
them helpless, or slow them down.
165
00:04:07,922 --> 00:04:11,825
It can cripple the bacteria and make
them helpless, or slow them down.
166
00:04:11,825 --> 00:04:15,062
Imagine being covered by thousands of flies.
167
00:04:11,825 --> 00:04:15,062
Imagine being covered by thousands of flies.
168
00:04:11,825 --> 00:04:15,062
Imagine being covered by thousands of flies.
169
00:04:15,062 --> 00:04:16,363
But, there's more.
170
00:04:15,062 --> 00:04:16,363
But, there's more.
171
00:04:15,062 --> 00:04:16,363
But, there's more.
172
00:04:16,363 --> 00:04:20,668
Do you remember the other part of C3—the C3a protein?
173
00:04:16,363 --> 00:04:20,668
Do you remember the other part of C3—the C3a protein?
174
00:04:16,363 --> 00:04:20,668
Do you remember the other part of C3—the C3a protein?
175
00:04:20,668 --> 00:04:23,237
C3a is like a distress beacon.
176
00:04:20,668 --> 00:04:23,237
C3a is like a distress beacon.
177
00:04:20,668 --> 00:04:23,237
C3a is like a distress beacon.
178
00:04:23,237 --> 00:04:27,641
Thousands of them flood away from
the site of battle screaming for attention.
179
00:04:23,237 --> 00:04:27,641
Thousands of them flood away from
the site of battle screaming for attention.
180
00:04:23,237 --> 00:04:27,641
Thousands of them flood away from
the site of battle screaming for attention.
181
00:04:27,641 --> 00:04:30,511
Passive immune cells notice the C3a proteins,
182
00:04:27,641 --> 00:04:30,511
Passive immune cells notice the C3a proteins,
183
00:04:27,641 --> 00:04:30,511
Passive immune cells notice the C3a proteins,
184
00:04:30,511 --> 00:04:35,115
and awaken from their slumber to follow
the protein tracks to the site of infection.
185
00:04:30,511 --> 00:04:35,115
and awaken from their slumber to follow
the protein tracks to the site of infection.
186
00:04:30,511 --> 00:04:35,115
and awaken from their slumber to follow
the protein tracks to the site of infection.
187
00:04:35,115 --> 00:04:39,185
The more alarm proteins they encounter,
the more aggressive they get.
188
00:04:35,115 --> 00:04:39,185
The more alarm proteins they encounter,
the more aggressive they get.
189
00:04:35,115 --> 00:04:39,185
The more alarm proteins they encounter,
the more aggressive they get.
190
00:04:39,520 --> 00:04:44,925
This way, complement guides reinforcements
exactly to the place where they're needed the most.
191
00:04:39,520 --> 00:04:44,925
This way, complement guides reinforcements
exactly to the place where they're needed the most.
192
00:04:39,520 --> 00:04:44,925
This way, complement guides reinforcements
exactly to the place where they're needed the most.
193
00:04:44,925 --> 00:04:49,630
So far, the complement has slowed
down the invaders and called for help.
194
00:04:44,925 --> 00:04:49,630
So far, the complement has slowed
down the invaders and called for help.
195
00:04:44,925 --> 00:04:49,630
So far, the complement has slowed
down the invaders and called for help.
196
00:04:49,630 --> 00:04:53,467
Now, it's beginning to actively help to kill the enemy.
197
00:04:49,630 --> 00:04:53,467
Now, it's beginning to actively help to kill the enemy.
198
00:04:49,630 --> 00:04:53,467
Now, it's beginning to actively help to kill the enemy.
199
00:04:53,467 --> 00:04:57,371
The first immune cells to arrive at the battlefield are phagocytes.
200
00:04:53,467 --> 00:04:57,371
The first immune cells to arrive at the battlefield are phagocytes.
201
00:04:53,467 --> 00:04:57,371
The first immune cells to arrive at the battlefield are phagocytes.
202
00:04:57,371 --> 00:05:03,043
Which means, cells that swallow you whole, trap
you in a tiny prison, and then kill you with acid.
203
00:04:57,371 --> 00:05:03,043
Which means, cells that swallow you whole, trap
you in a tiny prison, and then kill you with acid.
204
00:04:57,371 --> 00:05:03,043
Which means, cells that swallow you whole, trap
you in a tiny prison, and then kill you with acid.
205
00:05:03,043 --> 00:05:06,180
But, to swallow an enemy, they need to grab it first.
206
00:05:03,043 --> 00:05:06,180
But, to swallow an enemy, they need to grab it first.
207
00:05:03,043 --> 00:05:06,180
But, to swallow an enemy, they need to grab it first.
208
00:05:06,180 --> 00:05:11,217
Which is not easy because bacteria prefer
not to be grabbed and are sort-of slippery.
209
00:05:06,180 --> 00:05:11,217
Which is not easy because bacteria prefer
not to be grabbed and are sort-of slippery.
210
00:05:06,180 --> 00:05:11,217
Which is not easy because bacteria prefer
not to be grabbed and are sort-of slippery.
211
00:05:11,552 --> 00:05:14,722
But now, the complement that has
anchored itself to the bacteria
212
00:05:11,552 --> 00:05:14,722
But now, the complement that has
anchored itself to the bacteria
213
00:05:11,552 --> 00:05:14,722
But now, the complement that has
anchored itself to the bacteria
214
00:05:14,722 --> 00:05:19,660
acts as a sort-of glue that makes it easy
for the immune cells to catch their victims.
215
00:05:14,722 --> 00:05:19,660
acts as a sort-of glue that makes it easy
for the immune cells to catch their victims.
216
00:05:14,722 --> 00:05:19,660
acts as a sort-of glue that makes it easy
for the immune cells to catch their victims.
217
00:05:19,660 --> 00:05:21,095
But it gets even better.
218
00:05:19,660 --> 00:05:21,095
But it gets even better.
219
00:05:19,660 --> 00:05:21,095
But it gets even better.
220
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Imagine being covered in flies again.
221
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Imagine being covered in flies again.
222
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Imagine being covered in flies again.
223
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Now, imagine them turning into wasps.
224
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Now, imagine them turning into wasps.
225
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Now, imagine them turning into wasps.
226
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Another cascade is about to begin.
227
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Another cascade is about to begin.
228
00:05:26,900 --> 00:05:29,336
Another cascade is about to begin.
229
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On the surface of a bacteria, the C3
recruitment platform changes its shape again
230
00:05:29,336 --> 00:05:33,907
On the surface of a bacteria, the C3
recruitment platform changes its shape again
231
00:05:29,336 --> 00:05:33,907
On the surface of a bacteria, the C3
recruitment platform changes its shape again
232
00:05:33,907 --> 00:05:36,243
and begins to recruit new proteins.
233
00:05:33,907 --> 00:05:36,243
and begins to recruit new proteins.
234
00:05:33,907 --> 00:05:36,243
and begins to recruit new proteins.
235
00:05:36,243 --> 00:05:41,348
Together, they begin the construction of a bigger
structure: a Membrane Attack Complex.
236
00:05:36,243 --> 00:05:41,348
Together, they begin the construction of a bigger
structure: a Membrane Attack Complex.
237
00:05:36,243 --> 00:05:41,348
Together, they begin the construction of a bigger
structure: a Membrane Attack Complex.
238
00:05:41,348 --> 00:05:47,855
Piece-by-piece, new proteins shaped like long spears
anchor themselves deep into the bacteria's membranes,
239
00:05:41,348 --> 00:05:47,855
Piece-by-piece, new proteins shaped like long spears
anchor themselves deep into the bacteria's membranes,
240
00:05:41,348 --> 00:05:47,855
Piece-by-piece, new proteins shaped like long spears
anchor themselves deep into the bacteria's membranes,
241
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until they rip a hole into them that can't be closed again.
242
00:05:47,855 --> 00:05:51,258
until they rip a hole into them that can't be closed again.
243
00:05:47,855 --> 00:05:51,258
until they rip a hole into them that can't be closed again.
244
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Fluids rush into the bacteria and their insides spill out.
245
00:05:51,258 --> 00:05:55,162
Fluids rush into the bacteria and their insides spill out.
246
00:05:51,258 --> 00:05:55,162
Fluids rush into the bacteria and their insides spill out.
247
00:05:55,162 --> 00:05:56,762
They bleed to death.
248
00:05:55,162 --> 00:05:56,762
They bleed to death.
249
00:05:55,162 --> 00:05:56,762
They bleed to death.
250
00:05:57,231 --> 00:06:01,001
The remaining bacteria are maimed
and distracted by the complement,
251
00:05:57,231 --> 00:06:01,001
The remaining bacteria are maimed
and distracted by the complement,
252
00:05:57,231 --> 00:06:01,001
The remaining bacteria are maimed
and distracted by the complement,
253
00:06:01,001 --> 00:06:04,438
and quickly taken care of by the arriving immune cells.
254
00:06:01,001 --> 00:06:04,438
and quickly taken care of by the arriving immune cells.
255
00:06:01,001 --> 00:06:04,438
and quickly taken care of by the arriving immune cells.
256
00:06:04,438 --> 00:06:09,476
The invasion has been nipped in the bud before
it had the opportunity to become dangerous.
257
00:06:04,438 --> 00:06:09,476
The invasion has been nipped in the bud before
it had the opportunity to become dangerous.
258
00:06:04,438 --> 00:06:09,476
The invasion has been nipped in the bud before
it had the opportunity to become dangerous.
259
00:06:09,476 --> 00:06:11,744
You probably didn't even notice it.
260
00:06:09,476 --> 00:06:11,744
You probably didn't even notice it.
261
00:06:09,476 --> 00:06:11,744
You probably didn't even notice it.
262
00:06:12,079 --> 00:06:15,049
But while bacteria are not happy about complement,
263
00:06:12,079 --> 00:06:15,049
But while bacteria are not happy about complement,
264
00:06:12,079 --> 00:06:15,049
But while bacteria are not happy about complement,
265
00:06:15,049 --> 00:06:19,853
the enemies it might be the most
useful against are actually viruses.
266
00:06:15,049 --> 00:06:19,853
the enemies it might be the most
useful against are actually viruses.
267
00:06:15,049 --> 00:06:19,853
the enemies it might be the most
useful against are actually viruses.
268
00:06:19,853 --> 00:06:23,991
Viruses have one problem:
they need to travel from cell to cell.
269
00:06:19,853 --> 00:06:23,991
Viruses have one problem:
they need to travel from cell to cell.
270
00:06:19,853 --> 00:06:23,991
Viruses have one problem:
they need to travel from cell to cell.
271
00:06:23,991 --> 00:06:29,963
Outside of cells, they're basically hoping to randomly
bump against a cell to infect by pure chance.
272
00:06:23,991 --> 00:06:29,963
Outside of cells, they're basically hoping to randomly
bump against a cell to infect by pure chance.
273
00:06:23,991 --> 00:06:29,963
Outside of cells, they're basically hoping to randomly
bump against a cell to infect by pure chance.
274
00:06:29,963 --> 00:06:32,499
Here, they're completely defenseless.
275
00:06:29,963 --> 00:06:32,499
Here, they're completely defenseless.
276
00:06:29,963 --> 00:06:32,499
Here, they're completely defenseless.
277
00:06:32,499 --> 00:06:36,036
And here, complement is able to intercept and cripple them,
278
00:06:32,499 --> 00:06:36,036
And here, complement is able to intercept and cripple them,
279
00:06:32,499 --> 00:06:36,036
And here, complement is able to intercept and cripple them,
280
00:06:36,036 --> 00:06:40,374
so they become harmless and guide
the immune system to devour them.
281
00:06:36,036 --> 00:06:40,374
so they become harmless and guide
the immune system to devour them.
282
00:06:36,036 --> 00:06:40,374
so they become harmless and guide
the immune system to devour them.
283
00:06:40,374 --> 00:06:44,645
Without complement, virus
infections would be a lot more deadly.
284
00:06:40,374 --> 00:06:44,645
Without complement, virus
infections would be a lot more deadly.
285
00:06:40,374 --> 00:06:44,645
Without complement, virus
infections would be a lot more deadly.
286
00:06:44,645 --> 00:06:49,116
But wait, if we have such an effective
weapon, why do we ever get sick?
287
00:06:44,645 --> 00:06:49,116
But wait, if we have such an effective
weapon, why do we ever get sick?
288
00:06:44,645 --> 00:06:49,116
But wait, if we have such an effective
weapon, why do we ever get sick?
289
00:06:49,116 --> 00:06:52,453
The problem is that in a war, both sides adapt.
290
00:06:49,116 --> 00:06:52,453
The problem is that in a war, both sides adapt.
291
00:06:49,116 --> 00:06:52,453
The problem is that in a war, both sides adapt.
292
00:06:52,453 --> 00:06:55,322
For example, when the vaccinia virus infects a cell,
293
00:06:52,453 --> 00:06:55,322
For example, when the vaccinia virus infects a cell,
294
00:06:52,453 --> 00:06:55,322
For example, when the vaccinia virus infects a cell,
295
00:06:55,322 --> 00:06:59,458
it forces it to produce a protein
that shuts complement activation down.
296
00:06:55,322 --> 00:06:59,458
it forces it to produce a protein
that shuts complement activation down.
297
00:06:55,322 --> 00:06:59,458
it forces it to produce a protein
that shuts complement activation down.
298
00:06:59,860 --> 00:07:04,498
This way, the virus creates safe
zones around the cells it infects.
299
00:06:59,860 --> 00:07:04,498
This way, the virus creates safe
zones around the cells it infects.
300
00:06:59,860 --> 00:07:04,498
This way, the virus creates safe
zones around the cells it infects.
301
00:07:04,498 --> 00:07:09,470
When it kills them, and tries to infect more,
it has a higher chance of being successful.
302
00:07:04,498 --> 00:07:09,470
When it kills them, and tries to infect more,
it has a higher chance of being successful.
303
00:07:04,498 --> 00:07:09,470
When it kills them, and tries to infect more,
it has a higher chance of being successful.
304
00:07:09,470 --> 00:07:15,275
Or some bacteria, for example, can grab certain molecules
from the blood that keep the complement system calm
305
00:07:09,470 --> 00:07:15,275
Or some bacteria, for example, can grab certain molecules
from the blood that keep the complement system calm
306
00:07:09,470 --> 00:07:15,275
Or some bacteria, for example, can grab certain molecules
from the blood that keep the complement system calm
307
00:07:15,275 --> 00:07:17,311
and make themselves invisible.
308
00:07:15,275 --> 00:07:17,311
and make themselves invisible.
309
00:07:15,275 --> 00:07:17,311
and make themselves invisible.
310
00:07:17,311 --> 00:07:20,647
So the complement system,
while being extremely important,
311
00:07:17,311 --> 00:07:20,647
So the complement system,
while being extremely important,
312
00:07:17,311 --> 00:07:20,647
So the complement system,
while being extremely important,
313
00:07:20,647 --> 00:07:26,420
is only one player in the complex and beautiful
organization that is our immune system.
314
00:07:20,647 --> 00:07:26,420
is only one player in the complex and beautiful
organization that is our immune system.
315
00:07:20,647 --> 00:07:26,420
is only one player in the complex and beautiful
organization that is our immune system.
316
00:07:26,420 --> 00:07:32,158
A beautiful example of how many
mindless things can do smart things together.
317
00:07:26,420 --> 00:07:32,158
A beautiful example of how many
mindless things can do smart things together.
318
00:07:26,420 --> 00:07:32,158
A beautiful example of how many
mindless things can do smart things together.
319
00:07:34,328 --> 00:07:37,163
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320
00:07:34,328 --> 00:07:37,163
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322
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Without your direct support, this channel would not exist.
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327
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And it's hard to overstate how grateful we are for that.
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In 2019, an average kurzgesagt video
took at least 1200 hours to produce.
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In 2019, an average kurzgesagt video
took at least 1200 hours to produce.
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In 2019, an average kurzgesagt video
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We need months to research and write
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We need months to research and write
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Or, by getting one of our calendars or posters.
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