00:00It starts with a tickle in your throat that becomes a cough.
00:12Your muscles begin to ache.
00:14You grow irritable, and you lose your appetite.
00:17It's official.
00:18You've got the flu.
00:20It's logical to assume that this miserable medley of symptoms
00:24is the result of the infection coursing through your body.
00:27But is that really the case?
00:29What's actually making you feel sick?
00:31What if your body itself was driving this vicious onslaught?
00:37You first get ill when a pathogen like the flu virus gets into your system,
00:42infecting and killing your cells.
00:44But this unwelcome intrusion has another effect.
00:47It alerts your body's immune system to your plate.
00:51As soon as it becomes aware of infection, your body leaps to your defense.
00:56Cells called macrophages charge in as the first line of attack,
01:00searching for and destroying the viruses and infected cells.
01:04Afterwards, the macrophages release protein molecules called cytokines,
01:10whose job is to recruit and organize more virus-busting cells from your immune system.
01:16If this coordinated effort is strong enough,
01:19it'll wipe out the infection before you even notice it.
01:23But that's just your body setting the scene for some real action.
01:27In some cases, viruses spread further, even into the blood and vital organs.
01:32To avoid this sometimes dangerous fate,
01:35your immune system must launch a stronger attack,
01:38coordinating its activity with the brain.
01:41That's where those unpleasant symptoms come in,
01:43starting with a surging temperature, aches and pains, and sleepiness.
01:48So why do we experience this?
01:51When the immune system is under serious attack,
01:53it secretes more cytokines, which trigger two responses.
01:57First, the vagus nerve, which runs through the body into the brain,
02:02quickly transmits the information to the brain stem,
02:05passing near an important area of pain processing.
02:09Second, cytokines travel through the body to the hypothalamus,
02:13the part of the brain responsible for controlling temperature,
02:16thirst, hunger, and sleep, among other things.
02:20When it receives this message,
02:22the hypothalamus produces another molecule called prostaglandin E2,
02:26which gears it up for war.
02:28The hypothalamus sends signals that instruct your muscles to contract
02:32and causes a rise in body temperature.
02:35It also makes you sleepy, and you lose your appetite and thirst.
02:40But what's the point of all of these unpleasant symptoms?
02:43Well, we're not yet sure, but some theorize that they aid in recovery.
02:48The rise in temperature can slow bacteria,
02:51and help your immune system destroy pathogens.
02:54Sleep lets your body channel more energy towards fighting infection.
02:58When you stop eating,
02:59your liver can take up much of the iron in your blood.
03:03And since iron is essential for bacterial survival,
03:06that effectively starves them.
03:09Your reduced thirst makes you mildly dehydrated,
03:12diminishing transmission through sneezes, coughs, vomit, or diarrhea.
03:17Though it's worth noting that if you don't drink enough water,
03:20that dehydration can become dangerous.
03:23Even the body's aches make you more sensitive,
03:26drawing attention to infected cuts that might be worsening,
03:30or even causing your condition.
03:32In addition to physical symptoms,
03:34sickness can also make you irritable, sad, and confused.
03:39That's because cytokines and prostaglandin
03:41can reach even higher structures in your brain,
03:44disrupting the activity of neurotransmitters,
03:46like glutamate, endorphins, serotonin, and dopamine.
03:51This affects areas like the limbic system,
03:54which oversees emotions,
03:56and your cerebral cortex,
03:57which is involved in reasoning.
04:00So it's actually the body's own immune response
04:03that causes much of the discomfort you feel every time you get ill.
04:07Unfortunately, it doesn't always work perfectly.
04:11Most notably, millions of people worldwide suffer from autoimmune diseases,
04:16in which the immune system treats normal bodily cues as threats,
04:21so the body attacks itself.
04:23But for the majority of the human race,
04:25millions of years of evolution have fine-tuned the immune system
04:29so that it works for rather than against us.
04:32The symptoms of our illnesses are annoying,
04:35but collectively, they signify an ancient process
04:39that will continue barricading our bodies against the outside world for centuries to come.
04:47This says the symptoms of many events,
04:48it claims that the pleiscate Fermi disorder reactions are.
04:50Therefore, there are many of us who were?...
04:54JustAllah, because they realise you have this than liking to the body and saying,
04:59because someone wishes to be different in the story of a single person's life.
05:02These symptoms were not like a special scene so that they don't miss,
05:04must be Nokombo, or by the mãe and KenION re-re-repaneth channel now.
05:06None of us aren't aware of any of the consequences of this.
05:08And apparently, you'll see as your nic Talk godなんです.
05:11And now, if youporate from an article of the Ice slash jaupe,
05:12you're always playing the識 on plane for breakfast.
05:13Notолько not like the fact the main level of the movie,
Comments