okay nervous tissue you have a little bit of writing to catch up with me here sure you can do it so we're going to talk about nervous tissue I'm going to focus on neurons neurons send electrical signals in anatomy and physiology we call these Action potentials then there are neurog gal cells they essentially take care of the neurons but the big picture of what I want you to see here is that you have electrical signals going out from your brain to your organs and you have electrical signals going from your organs to your brain if you get a red pen we'll use that to talk about the motor output a motor neuron is going to make something move or work the targets are going to be muscle or glands three kinds of muscle smooth muscle cardiac muscle and skeletal muscle and really affecting a gland and is the smooth muscle that surrounds it so essentially that's like affecting the smooth muscle around a gland now it is true that there can be nervous input on other cells that cause all kinds of fascinating functions but for the purposes of this class if you just think of a motor neuron as making a muscle do something and understanding that that's smooth muscle cardiac muscle or skeletal muscle you'll be well prepared for a health career so the direction of the electrical signal or the action potential comes like this to the end of the neuron it only goes the One Direction so it's really important to know where this is coming from well this is the Soma or the cell body of a neuron all these are what are called dendrites and where would this be well it would be in the brain or spinal cord so it' be in the central nervous system and then the axon can project all the way out to a Target and that Target can be muscle smooth muscle cardiac muscle or skeletal muscle it could make the GI tract constrict it could make a blood vessel constrict it could make the uterus constrict it could make the heartbeat faster or slower it can make a skeletal muscle constrict harder or more gently okay then let's look at a sensory and we'll use blue for sensory now this would be where the action potential begins and this would be located in the organ so it might be a muscle sending stretch information so that you don't tear or a tendon those would also have Str stretch receptors what about pain receptors or just generalized touch receptors temperature receptors let's think about um senses that you have in your face these are what we call a special Senses cranial nerve number one gives you sense of vision it fires a so its Action potentials would be fired in response to light and then there's sound receptors they fire their Action potentials due to hearing waves sound waves in the air what about taste they fire their action uh Potentials in response to chemicals in the foods that you eat smell is just like that so both of these respond to chemicals and vision and sound they're responding to waves it's just light waves versus sound waves then there's something called oh wait that's not a special sense though so we've got we've got stretch receptors pain receptors touch receptors temperature receptors special Senses we went through there and then something called proprioception this has to do with gravity and what it does is the movement of the limbs is reported back to the brain so with your eyes closed you know where your arms are where your legs are where they are positioned okay so let's look back up at that sensory neuron again in this case instead of the action potential going from the brain or spinal cord out to the organ it's the other way around so it goes from the organ to the brain or spinal cord so compare that to the motor neuron it sends its signaling from the brain or spinal cord out to an organ maybe a muscle sensory does the other around the action potentials are fired from the organ to talk back to the brain or spinal cord so your brain or spinal cord can control what happens but your organs are always telling the brain or spinal cord how things are going and that communication allows the body to be able to maintain homeostasis sending a response when it's needed