Our bodies are full of nerves! How do they work? Why do we have an autonomic and a somatic nervous system? When do the sympathetic and parasympathetic systems kick in? And what's with the vagus nerve?
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00:00Hmm, there's always a lot going on in the body at the same time.
00:07But to keep everyone from just doing their own thing, the organs need to work as a team.
00:13Communication is key.
00:17And that's where the nervous system steps in.
00:20Or rather, the nervous systems, because we have more than one.
00:24Like everything else in the body, nerves are made of cells, neurons.
00:28To pass on a signal, they need a nudge from other neurons using chemical messengers called neurotransmitters.
00:35When the voltage inside a neuron reaches a certain threshold, an electrical impulse zips to the other end.
00:42At the end, it triggers the contact points, the synapses, to release more neurotransmitters,
00:47passing the message along, through the body, cell by cell.
00:53Most of this communication happens without us noticing.
00:57The autonomic nervous system quietly takes care of business, relaying instructions between the brainstem and our organs.
01:07It's run by two bosses with very different management styles.
01:13The sympathetic nervous system is the boss when stress hits.
01:17It cranks things up, telling the heart to beat faster, the lungs to supply more oxygen, and digestion to slow down.
01:25The liver jumps in, releasing extra energy in the form of glucose.
01:30The parasympathetic nervous system, on the other hand, has a more relaxed approach.
01:35Once the stress is gone, the heart and lungs can take a rest, and digestion starts working again.
01:41And the reproductive organs can do whatever they like.
01:49That can bring the sympathetic system rushing back in.
01:56The intestines have their own department, the enteric nervous system.
02:00It coordinates gut movements and the release of enzymes.
02:04It even has a hotline to the brain via the vagus nerve.
02:10But sometimes we don't want our body doing everything on its own.
02:13We want to take command.
02:21When we want to control and move our muscles on command, the somatic nervous system kicks in.
02:28It carries conscious instructions from the brain to the skeletal muscles, and also sends back touch signals from the skin.
02:37Sometimes the nervous systems clash.
02:40Reflexes like tears, coughing or sneezing are controlled by the autonomic nervous system, and they're really hard to suppress.
02:50When giving a speech, we do everything we can to stay calm.
02:55But once the sympathetic nervous system raises the alarm, our heart and lungs start to race.
03:01And all the brainstem can do is hope to escape as soon as possible.