hi everybody welcome back to miss angler's biology class i am miss angler in today's video we are going to be looking at a reflex arc and i'm going to be walking you through how the impulse travels through your spinal cord and how decisions are made when we speak about reflexes it's also at this point if you're not so familiar with the structures of the nervous system that you should go click the link above now to go watch an introduction to the nervous system where i walk you through the basic structures that you see today in this picture i'm also going to run through the significance of a reflex arc as you need to know why we actually have this particular structure now if you are new here don't forget to give this video a thumbs up subscribe and turn your notifications on because i post new videos every tuesday and thursday for grade 8 to 12 biology and as a little extra if you are in my trick and you need that little extra help um you should think about joining my membership where i upload my amazing summaries i do a lot more exam prep and i walk you through exam papers as well as having live lessons with me so we're going to start our journey with reflex arcs starting at the point that you experience the stimulus now you are generally going to experience your stimulus through your skin through your eyes maybe through your ears but in this example i'm just going to use your skin and these are a few of your surface skin cells and located inside of these skin cells are going to be receptives of some kind so i'm just going to draw those in red and there's one inside of each of them and they're all connected to each other and so these receptors which are in your skin are going to collect the information they're receiving and let's say for this example you've put your hand down on a hot stove now that information is going from those receptors and it's going to travel down a neuron and that neuron is going to enter into your spinal cord via the dorsal root of your spinal cord and it's going to make its way towards the gray matter now this particular neuron you're going to need to know this is a sensory neuron and it's a sensory neuron we know this because it's obviously bringing in the sensory experience what you're feeling we know it's also a sensory neuron because it's cell body which is this little thing i've drawn on the side here this circle is off to the side of it now once that information comes into the spinal cord it now needs to be transport transported excuse me into the actual spinal cord because the spinal cord is actually going to make the decision not the brain and so we need a specialized uh neuron and this specific specialized neuron sits in the gray matter the full length of it like that and now an integrative measure needs to be taken and so we call these neurons either connector or interneurons and this is where we'll make our decision so our spinal cord says we are putting our hand on a hot plate we are hurting ourselves we need to move so it makes a decision we're going to move and that's the choice now it sends that particular message to the next neuron which sits on the other side of the spinal cord and that neuron is our motor neuron and it makes a little synaptic join with our connector and it runs the other side or the dorsal side of our spinal cord and the spinal root and it goes out and towards its destination and so that's our motor neuron it's going to cause the movement now the motor neuron itself is attached or embedded in what we call an effector and in this picture here i'm just drawing a muscle a striated one one we would get in our skeleton and this particular muscle is going to help us move our hand away from the hot object and so we call this muscle a effector and muscles are examples of this glands are responsible as well for being effective and you can see the motor neuron sits inside the muscle it causes the muscle to contract and then you pull your hand away very quickly now in an exam you need to be able to explain what i have just said now and it's generally a describing question you're going to describe a reflex arc and how it works another thing they may ask you is the significance of a reflex arc like why does it happen and the reason is we need response quick and quickly to any kind of safety issues as well and that response is quick because it goes from the stimulus to the spinal cord and then you respond quickly and you move or and some of the examples i run through now you'll like blink and that's because we can bypass the brain the brain doesn't have to make any decisions the spinal cord makes all the decisions for us and this is also sometimes when you burn yourself on a hot plate you actually move before you feel the pain it's these split seconds where you didn't actually know you were burning yourself but your your spinal cord already knew that you were hurting yourself and so you quickly move away now some of these examples that i've listed here like coughing yawning and blinking they're not just the regular coughing and yawning and blinking these are all safety measures and what i mean by that is they are safety measures to prevent you from like dying so things like coughing something stuck in your track here the reflex to get that out is coughing if there's too much carbon dioxide in your blood you yawn more so you get more oxygen in and the likewise with blinking when somebody throws something at your face too quickly or you hear a large sound you generally blink as a way to protect your eyes because they're actually one of the most important receptor organs that humans have so we want to keep those safe and that's another way that they can ask this particular question the last thing they can probably do is ask you to draw a reflex arc now as always i like to finish off my lessons with a terminology recap you can use these words for flash cards and terminology is really important in life sciences so you need to know how to use these words properly the first thing we're going to look at was the reflex arc which is the actual pathway itself where the electrical impulse runs from the receptor into your spinal cord and then out to the effector that is the arc itself then we looked at receptors which are essentially the specialized cells that experience pain pressure temperature they tell you information from the outside of the body and it runs along the sensory neuron which is the neuron that carries that sensation it then goes into the spinal cord where we find the interneuron also known as a connector neuron and that neuron is where we make decisions that decision is then sent via the motor neuron which is a moving neuron it means it's going to make things move and that is sent to the effector which in this case was a muscle but it can also be a gland these are the structures that carry out the response that's what an effector is and we finally spoke about reflex actions and the actions were those examples where i said things like blinking sneezing coughing that's the action that's brought about now as always if you've liked this video don't forget to give it a thumbs up and subscribe and i will see you all again soon bye