1 00:00:00,560 --> 00:00:07,440 hello welcome to a new video of this unit nervous endocrine system today we're gonna see how the 2 00:00:07,440 --> 00:00:14,960 neurons connect one with another and they transmit the electric impulse all around our body also 3 00:00:14,960 --> 00:00:32,799 we are going to see our central nervous system get ready starting how the neurons transmit 4 00:00:32,799 --> 00:00:38,560 information from one to another we're gonna write the title 2.2 electric signals 5 00:00:40,960 --> 00:00:48,000 now we're going to make a pop-up marvelous pop-up that you love here okay in our notebook we need 6 00:00:48,000 --> 00:00:56,719 the white paper and we're going to cut a stripe which will be 30 centimeters long 10 centimeters 7 00:00:56,719 --> 00:01:07,599 why okay the first thing we cut 30 10 and then we make a flap at about 10 centimeters from the 8 00:01:07,599 --> 00:01:14,079 border okay so this is the first thing we need to do we have 30 centimeters times 10 and then we 9 00:01:14,079 --> 00:01:23,519 fold at 10. here we go think that we have the information imagine that we touch something with 10 00:01:23,519 --> 00:01:32,000 our hand and the information of that touch has to come from our fingers up to our brain and decide 11 00:01:32,000 --> 00:01:37,840 what do we do with this touch and then come back to our arm to take it back or to grab it. 12 00:01:38,799 --> 00:01:46,719 How does that happen? Because we have connections between neurons. How does this connection take 13 00:01:46,719 --> 00:01:55,200 place look at this picture this is the flap that we have made i have fold this part okay this is 14 00:01:55,200 --> 00:02:03,760 going to be the flap that will open and close okay this part will open and close you need to make all 15 00:02:03,760 --> 00:02:09,439 this drawing about the synapse how an ear on contact with another we have first of all the 16 00:02:09,439 --> 00:02:16,400 information imagine that we touch something we have some information that is going to get inside 17 00:02:16,400 --> 00:02:26,400 the neuron by electric signal very important electric signal all these process is made up 18 00:02:26,400 --> 00:02:34,000 by electric impulse so we have information coming by electricity and the information has to come 19 00:02:34,000 --> 00:02:43,759 from the presynaptic neuron to the false synaptic neuron so it travels from the dendrites coming 20 00:02:43,759 --> 00:02:50,800 from the dendrites, get to the cell body, down to the axon and then to the axon terminal. 21 00:02:50,800 --> 00:02:56,639 The axon terminal is the end of the journey for disinformation into this neuron, but then it jumps 22 00:02:56,639 --> 00:03:03,759 to the next neuron, we're going to see how in a minute, and gets to the postsynaptic neuron. 23 00:03:03,759 --> 00:03:12,719 In this postsynaptic neuron, the impulse continues by electric impulse. This part inside is what is 24 00:03:12,719 --> 00:03:22,080 called the synapses synapse and we're going to open this part to have all the information inside 25 00:03:23,039 --> 00:03:30,719 we have seen how the impulse goes from presynaptic neuron to the postsynaptic neuron from dendrites 26 00:03:30,719 --> 00:03:38,479 to the axon terminals but we're going to focus on this area the specific point where the information 27 00:03:38,479 --> 00:03:45,439 passes from one neuron to the next how does that happen let's see what i have made is that these 28 00:03:45,439 --> 00:03:51,759 circles that we made i have made it bigger imagine that we have an electronic microscope and we are 29 00:03:51,759 --> 00:03:58,639 going to see this specific area so we take our flaps here imagine that we have the presynaptic 30 00:03:58,639 --> 00:04:08,240 neuron we open it and we have this okay the circles is this one here what do we have okay 31 00:04:08,240 --> 00:04:15,039 this is the presynaptic neuron and this is the axon terminal. So we are in this part but in this 32 00:04:15,039 --> 00:04:25,199 neuron. And here we have the dendrite of the postsynaptic neuron. Therefore, the nerve impulse 33 00:04:25,199 --> 00:04:31,120 comes this way, from cell body to the axon and axon terminal. So we are in the axon terminal, 34 00:04:31,120 --> 00:04:37,759 the impulse comes and we have here some vesicles. If you remember from the unit that we talked about 35 00:04:37,759 --> 00:04:44,240 the cells and the different organelles we said that vesicles contain some substances that could 36 00:04:44,240 --> 00:04:51,120 be used inside the cell or released outside the cell how are they released they fuse with the 37 00:04:51,120 --> 00:04:58,160 membrane with the cell membrane and they release their content outside the cell so we have vesicles 38 00:04:58,160 --> 00:05:07,040 with things inside these substances these green dots are called neurotransmitters neurotransmitters 39 00:05:07,759 --> 00:05:14,399 are different substances they could be proteins they could be lipids which cell information 40 00:05:15,040 --> 00:05:23,439 transform the electric information to chemical information it could be for example caffeine 41 00:05:23,439 --> 00:05:31,120 could be for example adrenaline for example if you're very nervous your adrenaline is really high 42 00:05:31,120 --> 00:05:36,879 because you're under stress or maybe if you are doing sports for example your body thinks that 43 00:05:36,879 --> 00:05:43,439 you are under stress and you need to rush and you need to run so your adrenaline is really really 44 00:05:43,439 --> 00:05:50,079 high that means that in the in this part the neurotransmitters of adrenaline are going to 45 00:05:50,079 --> 00:05:57,120 be released so this neurotransmitter are inside the vesicle they fuse with the cell membrane 46 00:05:57,120 --> 00:06:02,480 and they are released into this space between the presynaptic and postsynaptic neuron which 47 00:06:02,480 --> 00:06:12,319 is the synaptic cleft synaptic cleft in spanish and the dura synaptica so presynaptic and 48 00:06:12,319 --> 00:06:18,800 postsynaptic neurons are not in touch okay they do not touch each other they have a space here 49 00:06:18,800 --> 00:06:24,240 where the neurotransmitters are released and in the postsynaptic neurons we have some receptors 50 00:06:24,240 --> 00:06:31,199 that are going to take the neurotransmitter and transform that chemical signal into electric signal 51 00:06:31,199 --> 00:06:37,439 which is going then to pass to the cell body, to the axon, to the axon terminal and continue 52 00:06:37,439 --> 00:06:46,189 and continue the journey all the time. So basically, making a summary, electric signal comes, 53 00:06:46,189 --> 00:06:50,910 activates vesicles, vesicles release the neurotransmitter into the synaptic cleft, 54 00:06:50,910 --> 00:06:57,310 they move to the receptor of the postsynaptic neuron and then in the receptors it transforms 55 00:06:57,310 --> 00:07:04,110 to a nerve impulse that travels really, really fast. It takes a really short time, I can tell you, 56 00:07:04,110 --> 00:07:11,230 really. If not, you won't be able to hear me right now, or to see me, or to think what the hell is 57 00:07:11,230 --> 00:07:20,350 she talking about. There's still a space here. If we open this, we should be having here a space 58 00:07:20,350 --> 00:07:27,550 which is blank, we're going to copy the definitions of neurotransmitters and nerve impulses. 59 00:07:28,750 --> 00:07:35,870 Nerve impulses, electric changes in the membrane in order to transmit information by electric 60 00:07:35,870 --> 00:07:42,829 signals. Neurotransmitters, chemicals which allow the transmission of signals from one neuron to 61 00:07:42,829 --> 00:07:51,470 the next across synapses. dopamine acetylcholine. Now that we know how neurons 62 00:07:52,189 --> 00:07:59,470 take information from one to another, let's see the different parts of the nervous system. Before 63 00:07:59,470 --> 00:08:04,670 before you write anything on your notebook, I'm going to explain you what we're gonna do here. 64 00:08:05,230 --> 00:08:11,069 The nervous system is very complex, has a lot of names, there are different parts of our body, 65 00:08:11,069 --> 00:08:19,790 a different function. What we are going to do is to do a super outline. With this super outline, 66 00:08:19,790 --> 00:08:28,589 look, I used really, really tiny writing and it took me a whole bit. So, please, take your notebook. 67 00:08:29,870 --> 00:08:37,549 Either one thing is that you can use two pages. You open and you take the left and right side of 68 00:08:37,549 --> 00:08:43,549 your notebook in case you need more space for example to have this outline but i want this 69 00:08:43,549 --> 00:08:52,269 outline in one single paper i mean that i want you to have an overview of all of it i don't want to 70 00:08:52,269 --> 00:08:59,389 have the first part of the central neural system on one page and then the peripheral neural system 71 00:08:59,389 --> 00:09:08,669 in another page okay so i want everything on one paper as i said it could be this is the left part 72 00:09:08,669 --> 00:09:16,190 the right the left part of your notebook and this is the right part but all that you can see with 73 00:09:16,190 --> 00:09:20,669 one side point number three nervous system 74 00:09:20,669 --> 00:09:30,309 let's start it we have two parts in our nervous system we have the central nervous system and the 75 00:09:30,309 --> 00:09:36,649 peripheral nervous system today we're going to focus on the central nervous system and tomorrow 76 00:09:36,649 --> 00:09:45,090 we'll start with the peripheral nervous system that's why i wrote it really really down on the 77 00:09:45,090 --> 00:09:51,190 board okay the difference between central nervous nervous system and peripheral is that the central 78 00:09:51,190 --> 00:09:56,149 receives the information and takes decision according to it according to the information 79 00:09:56,149 --> 00:10:02,590 it receives but the peripheral nervous system is the responsible for receiving that information 80 00:10:02,590 --> 00:10:13,309 and making the action so basically this is going to be compound of the brain and the spinal cord 81 00:10:13,309 --> 00:10:18,809 Whereas the peripheral nervous system is going to be compound of all the different nerves in our body 82 00:10:19,909 --> 00:10:23,649 Our central nervous system has three main functions 83 00:10:24,169 --> 00:10:31,149 first of all integrates the information that receives if I'm talking to you is because I 84 00:10:32,490 --> 00:10:37,690 Have a hearing and I hear that there is nothing disturbing me here 85 00:10:37,690 --> 00:10:44,570 that I can see the camera and I know that I'm looking to the camera and I have the information 86 00:10:44,570 --> 00:10:54,629 here with all the things that I want to tell you and all this is integrated in my brain so the 87 00:10:54,629 --> 00:11:00,190 function is to integrate the information that received from outside the world and also inside 88 00:11:00,190 --> 00:11:09,789 my body also to prepare our coordinate responses my response to all the information surrounding me 89 00:11:09,789 --> 00:11:17,070 is that i'm going to talk that will be the response so integrate information and coordinate 90 00:11:17,629 --> 00:11:26,509 and prepare responses our central nervous system is very important therefore i need to be protected 91 00:11:26,509 --> 00:11:34,669 how it could be protected by some bones like our skull and our spine all the bones that we have in 92 00:11:34,669 --> 00:11:42,269 our spine and our skull try to pretend to protect the central nervous system also by membranes 93 00:11:43,149 --> 00:11:48,110 we cannot have the central nervous system in contact with the bones so we have a membrane 94 00:11:48,110 --> 00:11:56,269 surrounding it that is called the meninges meninges that's what can cause the illness 95 00:11:56,269 --> 00:12:03,789 of meningitis if the these membranes are inflamed because of a virus for example or because 96 00:12:03,789 --> 00:12:09,389 of a certain illness then we can develop meningitis and it's really really dangerous 97 00:12:09,389 --> 00:12:20,590 we have also a fluid between membrane and also the nerves that is the cerebrospinal fluid 98 00:12:20,590 --> 00:12:28,690 which in Spanish we call it líquido cefalorraquídeo in this place in this fluid is when for example 99 00:12:28,690 --> 00:12:35,230 we are going to go to the surgery and we need some anesthesia for example the epidural 100 00:12:35,230 --> 00:12:45,769 epidural, anesthesia epidural, that is going to be injected here in the cerebrospinal fluid 101 00:12:45,769 --> 00:12:53,750 inside our spine. And it's not only for pregnant women, okay? It could be to any of us could go 102 00:12:53,750 --> 00:13:00,830 to surgery and we might need epidural. So it's very important because it's going to protect 103 00:13:00,830 --> 00:13:08,029 the central nervous system inside our central nervous system we have two different types of 104 00:13:08,029 --> 00:13:14,669 tissues depending well they are not really really tissues they are different parts of the neurons 105 00:13:14,669 --> 00:13:18,429 we have the gray matter and the white matter which in spanish are 106 00:13:18,429 --> 00:13:27,570 maybe you have here about the gray matter because if people people who are very clever have a lot 107 00:13:27,570 --> 00:13:34,850 of gray matter. What is the gray matter? The cell body of the neurons and the dephrytes. 108 00:13:34,850 --> 00:13:41,330 What is the white matter? The axon and the myelin sheaths. Myelin sheaths are white, therefore they 109 00:13:41,330 --> 00:13:49,889 have that color. Our central nervous system is compound of two different parts. The spinal cord, 110 00:13:49,889 --> 00:13:56,129 which in Spanish we call it medula spinal, and the brain, which in Spanish is encephalo. 111 00:13:56,129 --> 00:14:05,409 yeah it's a trick that brain usually we translate it as cerebro but we do not only have a cerebro 112 00:14:05,409 --> 00:14:13,730 inside our brain you'll see why but let's start with the spinal cord we're going to see how is 113 00:14:13,730 --> 00:14:20,210 our spinal cord inside we're going to make this drawing you don't need to make it there usually 114 00:14:20,210 --> 00:14:26,769 what i recommend is that you make a flap here okay you make this throw it in a separate piece of 115 00:14:26,769 --> 00:14:33,970 paper and you will glue it later so it opens and close so it does not occupy some space of your 116 00:14:33,970 --> 00:14:42,610 outline so what do we have imagine that we cut here ourselves in this part of our spinal cord 117 00:14:42,610 --> 00:14:48,769 and we see it under the microscope we'll see something like that something resemble a 118 00:14:48,769 --> 00:14:55,809 butterfly we always say that it has a butterfly shape the spinal cord we have the gray matter 119 00:14:55,809 --> 00:15:01,730 on the outer part i was sorry the white matter on the outer part and the great matter in the 120 00:15:01,730 --> 00:15:08,769 inner part also there is a hole in the middle which is called the penema there is where is 121 00:15:08,769 --> 00:15:16,370 going to be the cerebral spinal fluid in our spinal cord here in the middle also out of our 122 00:15:16,370 --> 00:15:24,809 our spinal cord get out the nerves. The nerves are going to get along our body and they are going to 123 00:15:24,809 --> 00:15:32,549 send the information to the muscles, to the different organs to perform functions. 124 00:15:33,850 --> 00:15:40,629 We have two functions of the spinal cord. Let's see the first one, the reflex action, reflex. 125 00:15:40,629 --> 00:15:47,350 When we take our hand out of a fire because it's burning on, it's a matter of survival. 126 00:15:47,830 --> 00:15:48,809 So we cannot think. 127 00:15:48,970 --> 00:15:52,649 Rapid action of no thinking, those are the reflexion actions. 128 00:15:53,009 --> 00:15:53,990 How does that happen? 129 00:15:54,169 --> 00:15:54,669 Steps. 130 00:15:54,990 --> 00:15:59,009 First of all, we're going to receive the stimulus in our receptor. 131 00:15:59,389 --> 00:16:00,990 In this case, it would be our touch. 132 00:16:01,549 --> 00:16:09,850 From the touch, we have a sensory neuron that comes from our hand up to the spinal cord. 133 00:16:09,850 --> 00:16:15,629 In the spinal cord, here, in this area, comes the nerve of the sensory nerve. 134 00:16:16,090 --> 00:16:24,470 We have an interneuron that is going to connect this sensory neuron that is coming inside with the motor neurons. 135 00:16:24,610 --> 00:16:31,610 The motor neurons send the signal getting out of other point of the spinal cord to the effector. 136 00:16:31,830 --> 00:16:36,070 The effector, in this case, will be my hand, and the effector produces some responses. 137 00:16:36,070 --> 00:16:38,549 In this case, I get out of the fire. 138 00:16:39,850 --> 00:16:46,370 Other function that the spinal cord has is to be a pathway first from sensory to the brain. 139 00:16:46,909 --> 00:16:51,129 So if, yeah, okay, if we touch something and it hurts, we get it back. 140 00:16:51,230 --> 00:16:53,929 But imagine that I want to grab something. 141 00:16:54,590 --> 00:16:56,830 I need to touch it, okay? 142 00:16:57,049 --> 00:17:02,470 So this sensation comes from my hand, it gets from the nerve to the spinal cord, 143 00:17:02,529 --> 00:17:04,390 and then it needs to be sent to the brain. 144 00:17:04,390 --> 00:17:10,829 so the spinal cord is going to be like a highway that is going to take these nerves 145 00:17:10,829 --> 00:17:20,609 up to the brain and then from the brain is going to be also a pathway the highway of the nerves 146 00:17:20,609 --> 00:17:29,190 which is going to get back to the effector so i can grab this eraser this is all for today of 147 00:17:29,190 --> 00:17:35,109 our outline. Next day we continue with brain and peripheral nervous system.