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Nervous system and Action Potential

Added Apr 12, 2016 •

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okay you welcome to chapter 28 chapter 28 is on the nervous system kind of have a different set up I'm in the broom and I've got my laptop down with some my lap and holding the microphone and so we'll see how it goes mine every person is definitely in his feet getting to work out as it go through this is it gorgeous picture of a looks like a computer simulation of a neuron from National Geographic and then this is one of the picture of a brain looks like other kind of models with all the function MRI for taking a picture of what parts of the brain are actually active at a certain point in time if we could summarize what chapter 28 is about it's really about just three things burping it's about is about neurons and and how neurons are built and then how the whole nervous system is going to put together second thing is on an potential you really understand how a nerve fire and how that that signals sent down the neuron and then the last thing it's about is about the human and have any brains can organize the 3:30 or with the nervous system nervous system has two parts to it that the central nervous system and has the peripheral central nervous system going to be the brain and the spinal cord and the peripheral nervous system is going to be getting sensory input like my eyes and I are getting Century input from invite environment and then I'm able to think about it and then I'm able to use motor output to do things like move my hands if we look at how the neuron directly put this is one we looked at in class if you hit yourself right here in the front of the tendon on the front of your knee your body thinks that you're falling forward and so a quick Reef if you take out your leg how did that work you have a sensory neuron that sound with him that we're going to send a message this eventually going to go into the spinal cord and then pictures of reflex is not going to go all the way to the brain but it's going to have what's called an interneuron here in between Iran and then is going to send a message right out back to those muscles in Tulsa the functional unit of the nervous system is called the neuron another word one nerve valves going to be called in there aren't got some part that you really want to become familiar on the side Day of the Dead dendrites and rice are kind of like branches of a tree they're going to pick up information a lot of time there connected to other neurons this is the tell Daddy and said that's going to contain like the nucleus and all the other organelles for the cell needs to work most of the length of the neuron is actually in the axon and yet from X little girl for example all the way down your leg and so the complete pretty long we have a number of support cells and some one of the big ones as far as I can go is that we've got a myelin sheath in other words either fat felt that rap about and what that does is increases the speed like a hundredfold of that signal is it goes down the there are now I said the action potential is really important and it is action potential is how that information is sent down the neuron and if you think it works electricity doesn't really work that way it's more like I think of it like chemical Domino's that are falling over the best way to think about it you hear me say this a lot in class but a good way think about a neuron is that it's like a healthy banana what does that mean if you're a salty banana then you've got a lot of potassium and you can see that on the inside septic a place and then you have a lot of sodium on the outside and so there's 30 and I like to remember is like 30% sodium chloride and so a neuron is set up with a membrane potential another word for the negative micro voltage on the inside compared to the outside what does that mean it hasn't people to do work another which we could actually measure a Volt across that if we had a little voltmeter that we could stick in there how did we build that it all call the sodium potassium pump the sodium potassium pump and remember the active transport for putting ATP in to do this it's something sodium to the outside and something to talking to the inside but we're pumping more sodium out then with something potassium you welcome proteins on the inside which have a negative charge that I could just said overall charge now what so if we break it down is something happens on one side of the neuron and other words I can push on my head and going to be changing those Sensory neurons at this point of my head and and it makes a cash game at Cascade is going to be an action potential what it look like will this is what it looks like if we compare it to a membrane potential or if millivolts on this site so a regular on is going to sit right here at -70 and said we also have a potential or to me a threshold of around -50 so what happens first well there are gated Pathways and those allow sodium to come and then there are other ones that allow potassium to go out since if something happens where we open up those sodium Gates and sodium starts to flow in what does that do to the is actually going to move it more positive because we're moving more of those positive charges to the inside and that's sodium stuff to move in that opens up more of these play the channels and more sodium starts to pour in until we eventually hit with all the threshold if we hit that point then I'll hex going to break me if you don't then just be back to that membrane potential do hit that threshold then we're going to see his big swing is all the 30 a month and dropped and then eventually we reach a point where the phone they're going to close and we're going to open up the potassium Gates caffeine is been going to start flowing out of the cell and then we are going to swing back to the negative we're going to undershoot on this time you port and part of that under shooting is it that keeps our our action potential moving in One Direction another way that tent can I go back self defense of the difference between me hitting myself like Vera me hitting myself like that is the number of action potentials and so a little signal is going to be a few action potential per millisecond but if I get a big hat like a hit like that it's going to be a bunch of action potentials really quickly and not only are we able to send pick up the signal but we're also able to measure how big the signal that no one didn't complain about neurons they're not connected hardwire to each other there's some electrical synapses and some organisms but enough we have this chat which is right between the middle and so we have narrow Tramp how's it going to be chemical until as that action potential arrives at the center at calcium is going to start flowing into this could be the presynaptic side and that's going to trig river lead to these neurotransmitters what do they do they just diffuse across that Gap and interact with a channel on the other side and that's going to open up that ION channel what surface when sodium is in a surf flowing in and said that says another Action Potential on the other side now all neurons are getting a bunch of signals they're saying it's time for you to fire first time for you not to fire the summation of all of those that sit teleia a neuron if it should fire in it on different got more complex over time it started with a pretty simple kind of a let me spend forward a little bit they started with a simple kind of a nerve neck and then true time gotten more complex and so a species have become bilaterally symmetrical in other words they cut the eyes front then the nurse have also kind of cephalized in other words they've moved up to a brain in the front of the hell that's been since their we are ventrally had something like that we got all of those neurons which are centered in the brain and then the brain is able to make decisions in and send messages out another important Point here that I failed to mention is that you've got a three real spinal fluid is finished around that whole brain and it and so what we have is a blood-brain barrier between our blood and then and our brains and tell what that does is lie nutrients and oxygen to get in but it doesn't allow toxins and things like that for the human brain go that's really important you can start here at the bottom we kind of called this behind brain or this is going to be right at the bottom is going to be the brain and brain-stem especially as you move up to the medulla and Ponder in charge of breathing so those really core body function we done move up into the midbrain in this is her information is kind of going to be routed we can think of that like fatpipe in information is just coming right through it another couple important part so we have up here is the this is the hypothalamus remember that the really important in the endocrine system move that pituitary sitting right underneath that you don't have the thalamus on top of that and that's part of the forebrain and the salamis is taking information and it's rounding it to the part of the brain and so another words we process different things in different parts of our brain and then eventually we get up to what's all this syrebral cortex I just got a little what time left Revo cortex is wondering where you're going to hold things like put the memory that's where we're going to do a lot of the processing that I'm doing right now one thing I forgot how is the cerebellum cerebellum is kind of in charge of coordination for the kind of parts of the brain and human brain is probably we could one of the most sophisticated things has ever evolved probably in in the known universe and would just starting to figure it out

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Nervous system and Action Potential

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