I've run dr. Mike here in this video we're looking at neurotransmitters neurotransmitters are chemicals that are produced and released by neurons and they can either have an excitatory or inhibitory effect now if we look at a neuron that's releasing a neurotransmitter it releases it into this gap this gap is called a synapse and it's the gap between one neuron and the next neuron now neurotransmitters that will bind to the next neuron will either excite it to send a signal or inhibit it from sending a signal now neurotransmitters don't just bind to neurons they may also buy into tissues they could bind to muscles they could bind to cells or glands they can bind to multiple different what we call effectors something that will elicit some sort of change now there's over a hundred different types of neurotransmitters in the body in this video we're just going to go through some of the most common including acetylcholine noradrenaline and adrenaline which is also termed norepinephrine and epinephrine dopamine serotonin gaba glutamate and substance P now in order for these neurotransmitters to have their effect they must bind to specific receptors and depending on that receptor you could excite or inhibit that target organ gland neuron whatever it may be all right so let's first start with the siedel choline acetylcholine has two major types of receptors nicotinic and muscarinic now depending on what it wants to do depends on the receptor so for example in our peripheral nervous system remember our nervous system is divided into the central brain spinal cord and peripheral all the nerves that shoot out the way and come back in to the brain and spinal cord and the peripheral nervous system acetylcholine plays a really important role in skeletal muscle contraction meaning muscles attached to our bones will not contract allowing us to consciously move without acetylcholine now the specific receptor involved here is muscarinic receptors alright which means you can have certain drugs that we can use that can act on muscular receptors that can affect the way we move our muscles acetylcholine also plays an important role in the autonomic nervous system specifically the parasympathetic division this is the rest and digest in actual fact the autonomic nervous system which is sympathy dick fight-or-flight parasympathetic rest and digest they both use acetylcholine but the parasympathetic uses acetylcholine at every single neuron all right the sympathetic only uses it from the first neuron now if we just look at the simp the parasympathetic we've got the first neuron and the second neuron that second neuron then sends a signal and talks to the target effector it could be a muscle it could be a gland it could be a cell type whatever it may be all right now usually it's going to be the digestive system or the heart or the pupils or saliva glands this is the parasympathetic acetylcholine is released at every single point all right so it's very important in rest and digest but in a central nervous system brain spinal cord plays an important role in memory and cognition has and has been implicated in Parkinson's disease which is the most common movement disorder and Alzheimer's disease which is the most common neurodegenerative disorder as well all right let's now look at the catecholamines catecholamines is an umbrella for noradrenaline adrenaline dopamine all of these three neurotransmitters are produced by the amino acid tyrosine which we must get from our diet we can't produce ourselves well we can produce it from phenylalanine but we need to get phenylalanine from our diet as well now there's when we look at noradrenaline and adrenaline all right there's a couple of different receptors that are used you can have alpha 1 alpha 2 beta 1 beta 2 beta 3 let's ignore beta 3 because they're only found on fat cells and we don't actually have any drugs that really utilize this receptor and its function let's look at alpha 1 and beta 1 if noradrenaline or adrenaline balance of these receptors it's excitatory okay for example what you'll find is alpha 1 is found on our blood vessels for example so we're noradrenaline binds to alpha 1 blood vessels will constrict increase in blood pressure beta 1 is found at our heart when noradrenaline bonds through it increases the heart rate increases the contractile force of the heart you'll find that alpha 2 and beta 2 are inhibitory alpha 2 is found on the postsynaptic neurons so that's the second neuron and what it does is that auto regulates the sympathetic nervous system it stops the sympathetic nervous system from firing off any more signals so it's like a negative feedback system beta 2 if noradrenaline binds to this is found at our lungs and it opens the Airways up some more air come in and out now in the central nervous system adrenaline and noradrenaline are important for opioid release this is our endogenous opioid system so you know opioids are there to relax reduce pain anxiety this is involved in opioid release adrenaline noradrenaline in the para in the peripheral nervous system sorry noradrenaline adrenaline are the primary neurotransmitters for the sympathetic nervous system so Siddal choline important for the parasympathetic noradrenaline important for the sympathetic if we look at another catecholamine dopamine probably heard of this as a reward molecule our feel-good molecule well it does play role in all of these two major types of dopamine receptors dopamine one dopamine - if you buy into dopamine one it excites it's an excitatory signal and if it's dopamine - then it's going to be an inhibitory signal and then dopamine's involved in heaps of different stuff in a central nervous system motivation okay reward very important and motor control that's found in a deep part of the brain called the basal ganglia and it's involved in initiating motor movement and smoothing out motor movement now in people with Parkinson's disease that the neurons that make dopamine are dying off which means it's hard for them to initiate movement and also hard for them to smooth movement out so they give that resting tremor postural instability and shuffling gait in the peripheral nervous system dopamine plays a role in blood vessel diameter JIT motility and also the kidneys role in being able to excrete sodium as well serotonin alright serotonin is also known as 5-htt a couple of different types of serotonin receptors now serotonin receptor one and five is inhibitory serotonin receptors two three four six and seven is excitatory and it plays an important role in the central nervous system with sleep and mood but also in the peripheral nervous system plays a role in our GRT if serotonin is released by neurons in our gut that's right we've got neurons in our gut that released serotonin it stimulates the gastrointestinal tract to contract and push things through too much pushes it through far too quickly and it also plays a role role in bone remodeling it may help make bone stronger it may Bonz weaker depending on the situation so that's serotonins now gaba also known as gamma-aminobutyric acid Gabbar has two major types of receptors gaba a Gabbar be predominantly gaba is the main inhibitory neuron of the nervous system so it inhibits neurons from firing off that's its major role and in certain disorders like epilepsy or individuals that have seizures the drugs that may be given may stimulate gaba because if you stimulate it increase the amount in the system what it does is it stops neurons from firing off usually by throwing negative chloride into the cells if the cells become super negative called hyper-polarization they won't fire off now glutamate is actually the most common or most abundant excitatory neuron in the nervous system two major types of receptors NMDA in a MPA and again excitatory if stimulated and they will tell neurons to fire off you can have glutamate toxicity too much glutamate being released can actually kill brain cells and has been implicated in dementia that glutamate toxicity theory has been associated with dementia and Alzheimer's disease all right the last one I want to talk about this substance P substance P P for pain this is involved in the pain system the major type of receptor here is NK one and again excitatory anytime you experience pain painful stimulus it may be emotive and may be physical all right what is going to happen is substance P is released and in the peripheral nervous system and the central nervous system stimulates pain and inflammation so therefore some times we want to try and identify certain drugs that maybe we can use against substance P to help mitigate pain so this is a relatively quick run-through of some of the most common types of neurotransmitters