I'm Dr Natalie Chang neurologist and assistant professor of clinical neurology I'm here today to answer your questions from the internet this is nerve support [Music] at Emily flower asks if your brain doesn't have any sensory nerves that's why you can be awake during a brain surgery then what the heck are headaches it's true that the brain does not have any sensory nerves it has no pain receptors many other structures in the head and neck do so the meninges which is the covering of the brain as well as the blood vessels in the head and the muscles in the head and neck all have pain fibers these can all be affected when you have a headache at Kelly Shakur us why do they call it a funny bone ain't nothing funny about hitting that the funny bone sensation is when you actually hit the ulnar nerve which is pretty superficial right here as it comes around the medial epicondyle of your upper arm bone most people think that it's called the funny bone because it feels funny when you hit it but it's actually a really bad dad joke from the 19th century this bone is called the humerus and some people thought back then that instead of calling it the humerus they call it the funny bone at CoCo Noir ass why do our limbs fall asleep nation of our limbs falling asleep is called paresthesias that pins and needle sensation when we've compressed a peripheral nerve for too long and what happens isn't really that the blood flow has stopped to that limb it's more that that nerve can't send those electrical signals back to the brain to tell them that there's feeling in that limb when you stop that compression of that nerve like when you wake up and you feel that pins and needles it's really the electrical signals kind of going crazy because they're like oh finally we're no longer being compressed at erlen henriquez ass so how does general anesthesia work general anesthesia is actually one of the great Modern Marvels of medicine and really laid the foundation for surgery as we know it today before general anesthesia if you had to have let's say a limb amputated you were awake you could see everything and there was really not much pain control now you would undergo general anesthesia which is made up of several components so number one is being unconscious number two is not remembering any anything three is pain control four is maintaining your body's functions while you're out and then lastly we want to make sure that you have muscle relaxation and paralysis you can imagine all these things are important because if a surgeon is operating on you you don't want a moving patient you also don't want a muscle to be really rigid you really don't want to smell your burning flesh at Kelly hogaboom us is the sympathetic versus parasympathetic nerve system concept real and also if so what is the difference in terms I can understand reference I am like a Wily but well-meaning caveman well well-meaning caveman imagine a saber-toothed tiger is running after you and you need to respond the sympathetic nervous system is part of the autonomic nervous system and it helps mediate your automatic functions like breathing heart rate sweating and digestion if the saber tooth tiger is chasing you you want your heart rate to go up so that blood can get to all the organs in your body you want the arteries that Supply your muscles to dilate so that you can run away from the saber-toothed tiger and you really don't want to send blood to your gastrointestinal system because now is not the time to digest that food that you just ate in contrast the parasympathetic nervous system is more our rest and digest or feed and breed functioning and this is where digestion becomes a priority as well as reproduction at Dunkel uglis ass is the nervous system what causes anxiety because my system is freaking nervous technically yes the nervous system does promote the actual feeling of anxiety so fast heart rate trouble breathing kind of queasiness in our gastrointestinal system this is a fight or flight response being activated now when people have anxiety this response is on all the time which can be pretty taxing for our minds our bodies as well as our emotions at mohosa official asks about how fast do nerve impulses travel Action potentials can travel as quickly as 100 meters per second which is about 200 124 miles per hour for us non-metric system users they can travel more quickly if the nerve is covered in myelin myelin acts like insulation just like on an electrical wire that helps the impulse travel more quickly instead of having the electrical signal travel continuously down it can jump in between these fatty segments at film car stairs S I want to know how I can move my body like how can my brain send signals to my toes and tell them to move I don't get it the way your body moves is through a system called the cortical spinal tract and this is a big part of your motor systems let's say you want to move your toes our brain actually has a map of the body in the motor cortex and there is a toe Center actually here in the middle that will then send a signal to the spinal cord it sends fibers to your spinal cord on the opposite side of the body it crosses in the medulla which is at the base of your brain stem at saphrodite ass the nervous system is so weird like what is itching itching is pretty annoying but it's a pretty smart defensive mechanism so let's say you have a mosquito who's crawling on your arm you definitely want to know about that so that you can hopefully flick it away and it doesn't bite you this is sort of like a pain response but it kind of tickles but that's what itching's purpose is at Jenna TS why can we be tickled like what response is that tickling is a type of itch almost and we found that when people have done functional neuroimaging studies of the brain while being tickled that two areas light up so the somatosensory cortex lights up when you're being tickled so that's our touch processing center but also the anterior cingulate cortex which is right here and this is our emotional Center so there definitely is a touch but also emotional component to being tickled in terms of why we laugh when we're tickled some think it's a form of social bonding like between a baby and its parent and others think it's more of a sign of submission to your Tickler that you're done being tickled and they've won at Melody b123s the difference between central nervous system and peripheral nervous system is confusing me and I think it's meant to be straightforward the central nervous system includes your brain and spinal cord the peripheral nervous system is basically anything that is outside of the skull or outside of the spinal column so in this diagram the peripheral nervous system starts basically where these branches come off the spinal cord and you can see more peripheral nerves in the limbs here and here at Kagan Ellen asks does acupuncture work for chronic pain yes about 39 clinical trials found that doing acupuncture significantly improved the control of chronic pain at just Doza s why does pain have to be so painful you know so pain is a really smart defense mechanism by our bodies to avoid things that might potentially injure the body permanently like if you step on a nail you don't want to keep walking on that foot because every time you step down you're injuring your foot further it's a signal to you to fix whatever is is hurting you so that you prevent further damage at Prof cooler asks how do nerves regenerate nerves in the peripheral nervous system can regenerate and what happens is let's say there's some injury to a nerve the immune system is activated and it's kind of like New Year's Day in Times Square the cleaning crew comes up and just gets rid of all that debris until that debris is cleaned up the cell body in the main part of the neuron can't really give out directions to produce new axon endings at Thigh Master asks during a physical why does the doctor tap your knee with a hammer but when we're testing your reflexes in the exam room we're checking to see if your motor and sensory neuron reflex is intact when we tap your let's say your patellar tendon that cause causes a stretch in a muscle spindle this sends a signal back to the sensory neuron which activates a motor neuron in the spinal cord to cause your knee to kick up if this reflex is absent it could indicate that you have a lower motor neuron problem if it's overactive meaning it's too jumpy it can signal a problem with an upper motor neuron something in the spinal cord above the level of the knee-jerk reflex which is L3 L4 or something in the brain at e Martin 11s why do people have such different pain tolerances pain is actually both a physical and an emotional phenomenon it's been studied that various factors like history of Prior trauma lack of sleep female sex can give folks lower pain tolerances higher pain tolerance is associated with older age exercise activity as well as more social support at eat or asks seriously what is carpal tunnel what are you guys doing with your wrists I have never suffered this issue but I'm intrigued so carpal tunnel is when there's compression of the median nerve here in your wrist which is where the carpal tunnel is it's a pretty small tunnel where the tendons of a lot of the form our muscles run through as well if you get any type of repetitive stress injury like the common one is typing other people notice it with cooking or other types of frequent manual labor they can cause compression of this nerve at amnon 96s how does local anesthesia work medications like lidocaine or xylicane which you typically get at the dentist or first the minor procedures basically block the opening of voltage-gated sodium ions which means that you can't really have those Action potentials spread so it really stops electrical impulses at anesthesia BS would you fill me in on what brain zaps are that sounds terrifying so brain zaps are actually something that's more recently described in the early 2000s where people would notice that they would fill these electrical shocks in their head or it feels like buzzing we found that they're associated with stopping antidepressant medications it's also been described after people use ecstasy or stop taking other medications like benzodiazepines it might be some change to neurotransmitter levels as you've stopped taking these medications but we're still trying to figure out why they happen at ragde bouillon 31s why do nerves in the teeth have to exist freaking toothaches man your teeth are kind of precious in terms of you know once you have your permanent teeth you don't get new ones if you think about it it's also in the mouth which is where we put a lot of things that could harm us right you could eat bad food you could eat something sharp that could cause a perforation of your stomach so if there's a problem with your teeth you want to know quickly rather than letting it slowly Decay and potentially cause an infection those are all the questions hopefully you learned something today see you next time [Music]