hey everybody welcome to professor long lectures on anatomy and physiology I'm professor long as you guys know we're in this coronavirus shutdown so I'm doing some quick quick impromptu 1 take videos very crudely done for my students in my anatomy and physiology classes if you're out there in YouTube land and you stumble across these and you find them helpful awesome I'm doing rather simplistic basic understanding of some fundamental principles and then we can begin to add layers of detail to that over time this lecture is intended for my A&P one students my biology 24:01 or human av1 students this is going to be the nervous system lecture number six in a series of lectures so I've already done five lectures this is the sixth one we've covered the flow chart of the nervous system CNS pns affinity ferrant somatic autonomic all that stuff sympathetic parasympathetic you have to know that you have to know what sympathetic and parasympathetic effect for sure we've covered the shapes and morphology of neurons we've covered ion channels and how we establish resting membrane potential and graded potentials that we can mess with that we've done action potentials and the last video we did the summation of actual potentials spatial and temporal summation and we talked a little bit about action potential propagation action potential velocity myelination that's going to lead us to one other topic I don't know how much I'm going to do because again I'm trying to watch the timer and do all this the best way for my students well we are going to talk about here is synaptic activity we've talked about synaptic activity a great deal when we did the neuromuscular Junction so let's say we're at the end of an axon here and at the end of an axon I have a branch called a T load injury on you know I'm gonna draw a couple of these because one axon will branch into many T loaded area okay actually I'm just going to draw one big T load in really but if you know the shapes of neurons then you know that I have all these dendrites coming in to the soma a massively branched dendritic tree with other neurons synapsing on here we have the axon hillock and the axon the axon will branch and many many Tila indriya at one connection at one synapse with either a muscle cell at a neuromuscular Junction or another neuron at a neuro neuronal Junction neurotransmitter can be released from here it will cross the synaptic cleft and have some effect on the next neuron which will then have an effect on another neuron and so on and so forth this is how our nervous system carries information from point A to point B it's a series of electrical and chemical and electrical and chemical events at every synapse we release a neurotransmitter there are receptors and there are enzymes to break it down we're gonna focus in on on one of these synaptic knobs and that one synaptic cleft okay so follow along here again I'm doing all this stuff at home I got kids I got a puppy dog I got a lot of stuff making noise in the back room so just bear with me okay give me just a second I don't want to start this video over and lose it so I'm gonna try to figure out a way eventually to put a pad back here because this thing keeps knocking when I write I hope it's not bugging you too much in the videos so when we look at synaptic activity here's my to load entry on here's my synaptic knob I'm gonna leave some gaps here for a reason as an action potential arrives there's a voltage called an action potential we've studied that that's flowing down this axon and it hits these spots and the action potential travels down the axon and runs through the synaptic memory or through the cell membrane in these areas I have voltage-gated calcium channels that are felt forced to open with changes in voltage and calcium ions because there's a higher concentration of calcium outside the cell than inside calcium would come rushing into the neuron through the laws of diffusion usually when when indicating the stuff the dot-dash lines in the diffusion but all of these sorry these calcium ions are going to come flowing in here due to the laws of diffusion as you know the synaptic knob is filled with thousands and thousands and thousands of these little bubbles of membrane called synaptic vesicles I don't have the ability to draw the high number of them I'm going to draw a few here I'm not even going to take the time to fill all of them with neurotransmitter but suffice it to say that there's some chemical in these synaptic vesicles and all of this chemical in these synaptic vesicles can be released from these vesicles into a gap or space and minding one vesicle can hold thousands of these molecules there's a lot of these the drawings are just representations they don't show you the true number or scale size of things it's just to get you the idea okay so as these calcium ions rush in it causes proteins and the membranes of these vesicles to fuse with little docking proteins in the membrane of the synaptic knob and as lipids fuse with lipids they can fuse together and open up allowing the neurotransmitter to be released on the next neuron there's an area where I will have all these receptors and usually the receptors are either associated with or connected to another ion channel a chemically gated ion channel or in some instances the ion channel itself has little spot where the neurotransmitter can dock and open the channel the neurotransmitter binds here this channel opens so some integral membrane proteins are ion channels and receptors some integral membrane proteins in the postsynaptic membrane here are ion channels connected to a receptor and if the neurotransmitter binds of will open it either way when the neurotransmitter makes it across this synaptic cleft this is going be my pre synaptic neuron and the presynaptic membrane since this gap is the synaptic cleft we were at cleft as a gap then this would be called my postsynaptic membrane or postsynaptic neuron we're going to use this term presynaptic and postsynaptic a lot the postsynaptic membrane has many membrane channels or ion channels in its memories some of them are chemically gated when the neurotransmitter and you guys should know the definition of a neurotransmitter if you don't you need to relearn it okay or learn it for the first time a neurotransmitter is any substance that transmits a message from a neuron to another cell either a muscle cell at a neuromuscular Junction or another neuron at a neuro neuronal Junction so neurotransmitter is just this chemical that's going to communicate a message from this neuron to that cell now if this were another neuron let's say some of these are potassium channels some of these are sodium channels the effect that's going to happen at this channel is going to be dependent upon which neuro trips are with the neurotransmitter that binds to its receptor now something I want to get across to you the presynaptic neuron genetically they are basically a set up so that they can synthesize one neurotransmitter and one neurotransmitter only so let's say this neurotransmitter is acetylcholine then this neuron does not have the ability to release any alternate neurotransmitters okay the postsynaptic membrane can have receptors for multiple neurotransmitters let's say this receptor is for this neurotransmitter and then these receptors over here are for a different neurotransmitter and remember these neurotransmitters are going to have a specific three-dimensional shape and electrical electrochemical properties so that lets say maybe around the neurotransmitter like this one won't fit in that receptor they're not necessarily round but giving you some concepts and if I another neuron over here dumps a different neurotransmitter in then this neurotransmitter would not bind to one of these receptors like this because the shape of the neurotransmitter doesn't fit the receptor it will only fit say this one got it so specific neurotransmitters only bind to specific receptors they call it a lock-in key hypothesis just like I can have a bunch of keys on the keychain that look almost identical I mean all the keys that I have for the building that I teach in a lot of the keys look almost identical but there's just enough change in them that one key might fit in a lock but won't turn the tumblers it won't open it some neurotransmitters cannot open certain channels the postsynaptic membrane can have receptors for more than one neurotransmitter can have multiple receptors with the presynaptic cells if this one releases a specific neurotransmitter it can only release that neurotransmitter and not any others got it okay now we understand how we should understand how your synapses work there is also an enzyme sometimes more than one depending on the nature of the synapse but there's an enzyme that lives in the synaptic cleft that can break down this neurotransmitter if I pull saw just a small pulse accidentally maybe some calcium leaked in and I got a small pulse I don't want if I were at a neuromuscular Junction I don't want to have all these jerky movements I don't want to have my thoughts just kind of jumping out the way I don't want them so essentially a small dose of neurotransmitter may not make it across the synaptic cleft it might get all broken down before we stimulate the postsynaptic membrane so it takes a lot of neurotransmitter being released sometimes to actually stimulate so there's sort of a buffer zone where nothing can happen because the enzyme wipes it out also a lot of people think that once a neurotransmitter binds to a receptor it binds it stays bound what happens is they can bind and fall off and then read mind and fall off and rebind and fall off and rebind and fall off now if I have multiple neurotransmitters and a receptor one can bind if it pops off then another one can pop in as it pops off another one pops in so they're called binding constants and if you ever take any physical chemistry you'll do all these binding constants K on and K off it's a lot of fun mathematics if you're into this I've done lots of it in my day but it's not important so just note that when a neurotransmitter binds to receptor it can bind and pop off and if it pops off it gets removed then we stop the signal if we break down all the neurotransmitter so essentially here's the events and these are the events that are listed on page 70 of my notes said if you're following along in my class these are the steps of synaptic transmission in the first step an action potential will arrive at the synaptic knob and open some voltage-gated calcium channels in the second step the calcium ions are going to diffuse into the cell and cause synaptic vesicles to fuse with the synaptic membrane so all of this is going to be step two the calcium ion coming in and release a neurotransmitter in the third step the way I have it set up as the neurotransmitter will diffuse across the synaptic cleft and bind the receptors in the postsynaptic membrane and that will stimulate or alter the resting membrane potential now if this is an excitatory neurotransmitter this so would depolarize moving towards threshold they'd have an epsp if I release this neurotransmitter let's say it opens potassium channels the postsynaptic membrane would hyperpolarize moving away from threshold or be inhibited so what happens at the synapse depends on which neurotransmitter is binding to which receptors opening sodium or potassium channels nonetheless in the third step the neurotransmitter is going to travel across the synaptic cleft and open ion channels and alter the resting membrane potential now in the next step as the action potential ends and these calcium ions disclose we stop releasing the nerve transmitter so basically we go back to steps one and two and cancel those the action potential stops calcium channels closed I stop releasing neurotransmitter no as that happens these calcium Islands are actually going to be actively pumped out of this membrane any calcium that leaks in can get pumped out by a calcium pump so we actively pump the calcium back out of the neuron so as we stop the action potential and stop the release the neurotransmitter the calcium ions are being pumped out stopping neurotransmitter release and then over time either the postsynaptic cell or just within the synapse itself this enzyme will break down any free neurotransmitter left over ending synaptic transmission once all the neurotransmitter is broken down I can't stimulate the postsynaptic membrane this last molecule pops off and it gets digested by an enzyme that ends the the synaptic transmission so those are the five steps I kind of try to do it in five steps actual potential opens calcium ion channels calcium ions enter the cell and cause neurotransmitter to be released the neurotransmitter will cross the synaptic cleft and alter the resting membrane potential of the postsynaptic neuron when the action potential ends the calcium pumps begin pumping the calcium out ending neurotransmitter release from additional vesicles and then the enzyme and the cleft will digest all of the neurotransmitter now I've said this a number of times in previous lectures I'll say it again once you understand one synapse how it works you understand how all synapses work all you need to know is what is the name of the neurotransmitter what is the name of the enzyme what are the name of the receptors and does that receptor open chemically gated sodium channels and cause an epsp or does it open chemically gated potassium channels and cause an IPS P inhibit this neuron okay so on in my class I'm gonna give you some some basic generalities okay of several neurotransmitters and talk a little bit about some drugs that can affect the synapse so there's a table that my note said and I'm gonna I need to alter this and update it but nonetheless the first one on the list is acetylcholine now acetylcholine when we use this term urging it comes from the word ergo ergo and Latin can mean they're therefore or kind of means like there goes so if I say ergo Sydney that means my friend Sydney is going right so when we use the term urgent it comes from ergo so if I tell you that a synapse is in : urging synapse that means it uses the neurotransmitter acetylcholine and a couple of variations some of these neurotransmitters they have some sort of cousins that are very very similar in their three-dimensional shape but in a cholinergic synapse if I told you this synapse is cholinergic that means we know we're releasing acetylcholine here that means I know this enzyme is called acetylcholine esterase we've covered that with the neuromuscular Junction what you need to know is that acetylcholine can be excitatory on some cells acetylcholine when I put a plus that's going to mean excitatory is excitatory at a neuromuscular Junction on skeletal muscle so this were a skeletal muscle cell acetylcholine would open sodium channels causing skeletal muscle cell to depolarize fired actually potentially contract as you know the action potential would trouble this is from the last lecture test action potential travels down the sarcolemma down the t tubules shocks the sarcoplasmic reticulum into releasing calcium calcium binds to troponin and troponin changes shape will tropomyosin off the active site the myosin heads gravity pull sarcomeres contract muscle contracts all those steps are due to opening sodium channels and sodium depolarizing the motor endplate no it can be hidden inhibitory anytime I put a negative sign that means we're gonna inhibit that remains we're going to open potassium channels in this cell is going to hyperpolarize its inhibitory at the neuromuscular Junction on cardiac muscle acetylcholine actually opens potassium channels on your heart the heart muscle cell will hyperpolarize and it will slow your heart rate so acetylcholine is used as a drug when someone has tachycardia rapid heart rate you give them acetylcholine it can slow the heart rate to a normal rate so that they don't die of a heart attack the heart doesn't cramp up it will slow the heart rate back to a normal amount by the way I know many of my students always ask do we have to do math on this test you better get good at math because you're gonna have to do medical dosage calculations and I know what the colleagues that I meant you have to make a hundred on your medical dosage calculations in our nursing program or you can't finish so you better know how to do medical dosage calculations because what if you gave someone too much calcium I mean too much acetylcholine you can completely shut off the heart and kill somebody so there's a lot of pharmacology going on here so anyway the next type of synapse I want to talk about is called an adrenergic synapse okay so I'm gonna erase all of this you should have those notes they're actually all written out in my notes it already for you but and what we call an ADD on urgent synapse this means air goes adrenaline adrenaline can come in two forms one form is called and the most common form in the human body is norepinephrine and it has a cousin called epinephrine all of y'all have heard of an EpiPen and B comes from epinephrine so we abbreviate norepinephrine its abbreviation very often is n E and epinephrine is very often abbreviated as e so if I told you this was an adrenergic synapse then you know that this synapse is releasing adrenaline or norepinephrine and/or its cousin epinephrine so almost always adrenaline epinephrine and norepinephrine is excitatory open some kind of sodium channel causing the next cell to depolarize usually it's excitatory in our nervous system and on skeletal and cardiac muscle it's excitatory in the nervous system it's excitatory on skeletal muscle it's excitatory on the cardiac muscle so when you have an adrenaline rush your nervous system starts firing like crazy you get all amped up and excited and just can't shut up I can't stop moving can't sit still your muscles contract harder and faster when people have an adrenaline rush they'll lift a car to save a baby and normally they couldn't lift that much weight or you know if you're in basketball or something you might jump higher and dunk a ball when you have a breakaway you can get a little bit more muscle contraction on cardiac muscle they can epinephrine is excitatory if your heart rate is too slow and you take epinephrine it can speed up your heart adrenaline causes the heart to increase its contractions if you overdose someone it goes cause the heart to cramp and kill you now the way epinephrine works in an EpiPen is it's excitatory on the smooth muscle of many of our blood vessels and can cause them to constrict let's say someone goes into what's called anaphylactic shock you're allergic to peanuts or you get a bee sting and you're allergic to the bee venom an anaphylactic shock you get what's called systemic vasodilation all your blood vessels dilate and get very big if all the blood vessels dilate then the total systemic blood pressure drops and blood slows its flow if you don't get enough blood flow to your brain and your heart they're not getting enough oxygen and glucose to keep firing and functioning and then you can start to get lightheaded and pass out and if your heart stops you can die the EpiPen the epinephrine if you inject it in somebody who is susceptible to anaphylactic shock they carry an EpiPen that epinephrine will cost vasoconstriction and as those vessels constrict it raises systemic blood pressure and saves you or prevent you from dying of an affair shop so it's excitatory on smooth cardiac and skeletal muscle it's excitatory in the nervous system adrenaline was almost always excitatory there are actually a couple of areas where it can be inhibitory we're going to talk about one day we might talk about beta and alpha receptors and how they respond because there's different receptors to adrenaline but we're not gonna talk about that now okay so now another type of neurotransmitter if I tell you that this synapse is dopaminergic that means it uses dopamine and sometimes there are cousins to dopamine that can also stimulate dopamine receptors but that uses the neurotransmitter dopamine dopamine has several cousins by the way one is called 5ht which stands for 5-hydroxytryptamine if you notice it has an amine group on it an amine group is an NH two attached to something else it's a nitrogen based compound five atraxi tryptamine many of y'all have heard of serotonin probably if you've taken a psychology class and done some of this there's another dopaminergic synapse called gaba gaba stands for gamma amino butyric acid so tryptamine is an amino acid and 5-hydroxytryptamine just means we put a hydroxyl group on the number five carbon there's some organic chemistry lingo there so that you can figure out you know but all of these are considered to be mono amines they all have a single amine so they belong to a class of compounds called mono amines meaning they have a single amino group on them gaba has an amino group attached to the gamma carbon so we call it gamma amino the carbons are can be labeled alpha beta gamma Alpha Beta Delta Gamma so the gamma carbon has an amino group and the molecule that it sought is called butyric acid or butyrate which is a four carbon compound these are small molecules that all have a single to mean they all work very similarly in the sense that many of them are inhibitory in our motor system so before I get too far into this let's say I have a motor neuron that wants to fire on a muscle cell and make it contract and there's another neuron somewhere up in the brain that wants to tell it to fire well I have other neurons that release dopamine here dopamine sometimes is abbreviated as da dopamine can inhibit this motor neuron so that this neuron does not fire so that my muscles stay relaxed and I stay still if I stop this neuron from releasing a constant amount of dopamine then this neuron fires an action potential distant Iran fires and my muscles will contract so dopamine can be inhibitory on our motor system when we damage the dopamine neurons you see people start to get involuntary muscle contractions like in Parkinson's disease you see the head shaking or the shaking of the limbs and then so those are indications that there may be problems with the dopaminergic system that the dopamine synapses in the brain so dopamine is inhibitory on the motor system okay but it's not exactly at the motor neuron and then synapse here it's higher up in the system inhibiting those lower motor neurons from firing when you damage the dopaminergic system you get involuntary muscle contractions okay dopamine can be excitatory on some of the pleasure and mood centers of our brain so let me erase them a lot of this in the mood centers so let's say in the human brain I have some areas in here that are associated with our mood as long as I have a constant release of neurotransmitter so essentially these neurons are going to release constant amount of neurotransmitter and are constantly firing at a baseline then your mood states rather steady if I want if I get something exciting happening in my brain something stimulates these neurons to begin flooding the neuro the synapse with extra dopamine that I'm going to get extra stimulation my mood becomes elevated and get happy and excited at them all you know like if you make it a on a test you get a dopamine rush or if you know you score a basket or you win something on a video game this is you know getting involved in the dopaminergic system the reward systems in our brain we get rewarded with activities workout we get excited okay then I go back to baseline when the event goes away I go back to my normal mood constant release a neurotransmitter let's say a negative event happens in our life and our dopaminergic system shuts down or stops releasing as much neurotransmitter then your mood declines you get sad or depressed or just down a little bit kind of having a bad day or you can have you know very very low levels of your mood you can say chemical type of depression involves our mono amines either not enough dopamine release not enough serotonin release and gaba can play a role in some of our mood and pleasure centers and reward centers of the nervous system so our mono amines tend to be especially dopamine inhibitory on motor neurons and excitatory in our mood centers okay and before I finish the last ones I'm just going to tie this up with this one the enzyme that's in the synaptic cleft for the mono amines by the way is an enzyme I'm going to write this up here called mono amine oxidase which is abbreviated as Mao you may hear commercials talk about Mao is monoamine oxidase inhibitors you know there's always these commercials hey take this drug and they show people running through the field falling in love happy and all of this stuff take this drug it enhance your life except for don't take it if you have my blood reduces and you could cause any flatulence an anal discharge don't take it if you're on any of eyes if you're on antidepressants they make all this stuff in when they talk about Mao eyes that's a certain class of drugs that inhibit monoamine oxidase so let me just give you a basic understanding of it the chemistry is a little different but not too much so let's go back to our mood Center and our bringing I have a constant release of a certain amount of neurotransmitter so that my mood is rather steady and stable in some individuals for some reason it can be due to life events it could be due the way that you're genetically programmed and you're wired you don't release enough monoamine oxidase and so your mood stays low and you're somewhat depressed it's a type of clinical depression and chemical depression there are a number of things that can trigger depression this is just one example well one of the class of compounds that they can administer is called monoamine oxidase inhibitors because the enzyme monoamine oxidase is breaking down what little bit of neurotransmitter you have left so that you don't feel good monoamine oxidase inhibitors will bind up the monoamine oxidase and leave just a little bit of it if they get the dosage right functional so now the little bit of neurotransmitter gets crossed across the synaptic cleft stimulate your mood center and your mood gets rather normal no if you take another drug that inhibits the maoi it could trigger your depression again so there's a lot of drug interaction that you're gonna have to study when you study pharmacology but one way that pharmaceuticals can work in the nervous system at synapses is by inhibiting the enzyme that's breaking down the neurotransmitter okay so when people abuse a lot of central nervous stimulants cocaine ecstasy some of you guys have heard of the drug next to see that's on the streets they take it at Reims and the kids can't stop moving they're over stimulated everything's super heightened while it's stimulating the mood centres and inhibiting your or you're messing up sort of the dopaminergic system and you just keep moving and move it and move it ecstasy is related to a stuff called GHB which is gamma hydroxybutyrate which combined to these gaba receptors sometimes when you take some of these other drugs rather than inhibiting these neurotransmitters what if you take a drug that binds to these receptors and you flood your synapses with this drug that can bind to the same receptor as the mono amines well when it binds here it's gonna elevate your mood so it feels wonderful I've never abused any drug and I've taken any illegal drugs I was too afraid to mess up my brain chemistry but nonetheless some of those drugs can bind to dopamine receptors serotonin receptors or gaba receptors and stimulate the mood centers of your brain and the enzyme can break them down or breaks them down much more slowly so that you get this high this euphoric feeling for a long period of time that can lead to something dangerous and here's what happens if I continually overstimulate this neuron remember these proteins have to be synthesized and stuck in the cell membrane through protein sorting and they're going to break down so we'll remove patches of membrane and replace them so that we always have a constant number of receptors and let's say every one of these red marks represents the receptors for dopamine or serotonin or gaba depending on where we're at in the brain if I continually flood these synapses with the drug cocaine ecstasy GHB ice methamphetamine meth amphetamine so all of these drugs can bind to some of these receptors and elevate your mood and stimulate you and you can't stop moving tweakers are always tweaking and moving around and you're so stimulated well if you do it too often these neurons just get worn out cymatics can handle this so they just quit replacing some of these receptors and if I lose the receptors it's called down-regulating I'm gonna regulate the receptors but I'm going to take it down some now when I'm not on the drug I don't get the same level of mood and my mood can become depressed so people who've used a lot of these CNS stimulants that bind to our dopaminergic our serotonin urges or GABAergic neurons and synapses can damage their mood they create mood disorders where they can have wild swings and mood and very euphoric one day and just fly off the handle you see this some people who abuse too much methamphetamine they can't sit still and people who do too much X and and GHB they've you know they can't sit still if you watch a TV show when they're busting someone the cops can tell my friends were police officers and EMTs and emergency room physicians I saw when I worked in the medical field in the ER you would see these people that just they're amped out and you know it and eventually you can down regulate these neurons and do permanent damage to your nervous system some of these effects by the way can be reversed it depends on how much of the drug and how long you've abused it and it also depends on your genetic ability to replace the neurotransmitter under the receptors over time if you quit taking the drug sometimes your body will put the receptors back I should use the rhythm will start to restore these receptors back to normal levels sometimes the damage is permanent and it depends on how much of the drug how long you've used it and how badly you've damaged your nervous system by the way another way that we can affect this you know there are a number of nerve agents now from my class I'm just going to test you on cholinergic adrenergic and dopaminergic synapses you need to know where the excitatory where their inhibitory in the nervous system essentially everything that's written here endorphins by the way are compounds that are inhibitory for pain you get the term for morphine and is very powerful similar to heroin a very powerful pain inhibitor so endorphins are neurotransmitters that can be released in our body that can inhibit pain like if you get your arm ripped off and you don't feel it and Callens are what we sometimes call the feel bad molecules I'm not going to go on any detail but when we release a lot of them careful and so we tend not to feel real good like when you have the flu and you just feel like crud all over by the way endorphins not only inhibit pain they give a sense of euphoria as well when people run in long distances and your body wants to quit you can release endorphins it inhibits the pain and you get the runner's high it can be addictive just like morphine some people are addicted to running anyway I've talked a lot about how synapses work a lot of this I'm not going to test on in my class but I do want you guys to understand cholinergic means they use acetylcholine they are excitatory in skeletal muscle inhibitory and cardiac abner synapses are almost always excitatory at least for now until I tell you otherwise they're excitatory it's skeletal muscle and cardiac muscle and a smooth muscle that can cause constriction of blood vessels and they're excitatory in the nervous system get you all whoo thinking like 90 miles an hour dopaminergic synapses use dopamine and there's also GABAergic and certain Uruk synapses and they all use these compounds so if I tell you something urgent and you recognize the name that means that that neurotransmitter is used there you also know a little bit about the enzyme that's breaking them down at least in acetylcholine it's acetylcholine esterase for our dopaminergic citizens synapses it's monoamine oxidase and you have a little bit of understanding about synapses work this lasts a little bit I'm going to talk about again just like me talking about drugs is just information for you to have some understanding of how these things impact you if I have a drug that binds to calcium channels at the presynaptic neuron and blocks them from opening I've essentially shut that synapse off so there are calcium channel blockers that can have effects and other parts of the body like in the heart force cardiac muscle contraction if you're having too much heart contraction you can use calcium channel blockers to ease up on the heart make it not work so hard but then they're going to have effects in your nervous system if you take too much they can effect synapses and other places I have drugs or chemicals compounds toxins and poisons that can bind to calcium channels and open them causing the complete release of neurotransmitter which would cause an overstimulation of the next synapse so if I had something that did that at a neuromuscular Junction your muscles would be in paralysis cramped up there are drugs that can bind to they can enter the synapse and bind to these these vesicles and stop the release of the neurotransmitter I would shut that synapse off there are also drugs that can inhibit the action potential in the presynaptic neuron so that I never even reached the synaptic cleft shutting the synapse off there are drugs that can bind up the enzyme here so that when I do release the drug or the neurotransmitter I should say the neurotransmitter will bind here and not be broken down so I get a constant stimulus of the postsynaptic membrane colon esterase or esterase inhibitors will bind up a coat of acetylcholine esterase so that at a neuromuscular Junction if you release acetylcholine your muscles will cramp those are bug toxins they're all esterase inhibitors they inhibit acetylcholine esterase so when you spray the roach you'll see that they'll start to flap their wings and they go into such a rapid contractions they actually reach tetanus and cramp and they die eventually they stop breathing because it will paralyze our ability to breathe and thus the animals can die or the insects can die so I can also have drugs that bind to the postsynaptic membrane and mimic the drug if I took a sympathy mimetic drug it would mime or act like adrenaline sympathetic nerve narrow transmitter and cause me to get really excited so anytime you have a memetic drug something mimetic it minds or acts like that it'll bind to the receptors the problem is a lot of times that synthetic drug will not be recognized by the neuron max minner and it can't be broken down so you have to be careful and then we have some drugs that combine to the postsynaptic membrane and block these channels so that the neurotransmitter can't function there's a lot of pharmacology here I wish I had some time to go into all of it but you know we can block the the release of the neurotransmitter we can block the receptors at the postsynaptic membrane so the neurotransmitter cannot mind I can bind to the postsynaptic membrane receptors and stimulate this cell mimicking the neurotransmitter and the enzyme has a hard time breaking it down I can also inhibit the enzyme so that when I do release a little bit of the neurotransmitter it actually gets across four people on Meo eyes by the way sometimes they give you a dosage they're kind of guessing what your body chemistry is based on some factors and they tell you to take it for a few weeks and then come back and they want to see how it's affecting you they may have to adjust the dosages until they get it just right for your biochemistry so there's a lot more going on to medicine it's just as much an art as it is a science so I've talked a lot about a very small part of my note said on page 70 but I hope this gives you some understanding of synapses and how they work and some neurotransmitters how they work and how pharmaceuticals and neurologic agents can affect the synapse anyway hope you learned something hope you had as much fun as I did I'm going to stop this video here and we'll get on to video number seven in just a little bit thanks for watching hope you learn something hope you have as much fun as I did