 Hi everyone. Welcome to basic science series. I'm your host, Lokinder Kumar and today I'm here to announce that I'm going to start a small crash course on the nervous system. In this crash course I'm going to cover the basic topics of the nervous system such as what is the nervous system? What are the different components and what are the signaling pathways in the nervous system and what is the function of each component of the nervous system? In that video series I will also cover various diseases that are associated with the nervous system. In this particular video, I will introduce you to the nervous system components and for that I have made a small list of the topics that I will be discussing today. So I need to look at my monitor and explain all those topics that I'm going to cover today. The first topic is I'm going to cover what is nervous system. I will also cover the brain, the central nervous system, peripheral nervous system. I will also touch base on endocrine system and motor, afferent nerves, afferent nerves. I will also cover the spinal nerve and in association with that, I will cover parasympathetic nervous system, sympathetic nervous system, enteric nervous system as well as somatic and autonomic nervous system. I will also show you the structure of nerve cell as well as the structure of glial cell. In the end, I will explain you some of the diseases that are associated with the nervous system. So overall, I will try to introduce you the human nervous system and the basic components of the nervous system in this presentation. In the upcoming videos, I will cover the special topic of the topics of the nervous system and that will include the structure as well as function of the nerve cell as well as the other cellular components of the nervous system. So please stay tuned till the end of the video so that you can understand the basic concept and stay tuned so that you can understand the other concepts of the nervous system. So please subscribe to the channel and if you like the video, press the like button and with that note, let's jump on to the presentation part. Nervous tissue first arose in warm like organisms about 550 to 600 million years ago. Nervous system are found in most multicellular animals, but very greatly in complexity. The only multicellular animals that have no nervous system at all are sponges, placozones and mesozones, which have very simple body plans. The nervous system of the radially symmetrical organisms, Tinoforce, also known as comm jellies, and Nidadians, which includes C-animal hydrochorals and jellyfish, consist of a diffuse nerve net. All other animal species, with the exception of a few types of worm, have a nervous system containing a brain, a central cord and nerves radiating from the brain and the central cord. The size of the nervous system ranges from a few hundred cells in the simplest of worms to around 300 billion cells in African elephants. Nervous system is a highly complex and fascinating part of an animal that synchronize its actions and sensory information by transmitting signals from different parts of the body. Neuroscience is the field of science that focuses on the study of the nervous system. The nervous system detects environmental changes that affect the body and then works in association with the endocrine system to respond to such signals or changes. The endocrine system is a chemical messenger system comprising feedback loops of the hormones released by internal glands of an organism directly into the circulatory system. In vertebrates, the nervous system consists of two main parts, the central nervous system, CNS and the peripheral nervous system called PNS. The CNS consists of the brain and the spinal cord. The PNS consists mainly of nerves which are enclosed bundles of the long fibres or exons that connect the CNS to every other part of the body. Nerves that transmit signals from the brain are called motor or efferent nerves. While those nerves that transmit information from the body to the nervous system are called sensory or efferent. Spinal nerves are both functions and are called mixed nerves. The PNS that is peripheral nervous system is divided into three separate subsystems. The somatic, autonomic and the enteric nervous system. Somatic nerves mediate voluntary movement. The autonomic nervous system is further divided into the sympathetic and the parasympathetic nervous systems. The parasympathetic nervous system is activated in cases of emergencies to mobilize energy. While the parasympathetic nervous system is activated when organisms are in a relaxed state. The enteric nervous system functions to control the gastrointestinal system. Here I want to mention an important point that both autonomic and enteric nervous system function involuntarily. Nerves that exit from the cranium are called cranial nerves. While those exiting from the spinal cord are called spinal nerves. At the cellular level the nervous system is defined by the presence of a special type of cell called the neuron. Also known as the nerve cell. Along with neurons the nervous system contains other specialized cells called glial cells or simply glia. Which provide structural and metabolic support. Neurons have special structures that allow them to send signals rapidly and precisely to other cells. They send these signals in the form of electrochemical waves traveling along thin fibers called axons. Which cause chemicals called neurotransmitters to be released at junctions called synapses. We will cover these topics in our upcoming video lectures in detail. A cell that receives a synaptic signal from a neuron may be excited, inhibited or otherwise modulated. The connections between neurons can form neural pathways, neural circuits and larger neural networks. That generate an organism's perception of the world and determine its behavior. The central nervous system functions to send signals from one cell to others or from one part of the body to others and to receive feedback. Malfunction of the nervous system can occur as a result of genetic defects, physical damage due to trauma or toxicity, infections or simply senescence. The medical specialty of neurology studies disorders of the nervous system and looks for interventions that can prevent or treat them. In the peripheral nervous system the most common problem is the failure of the nerve conduction. Which can be due to the different causes including diabetic neuropathy and demyelinating disorders such as multiple cyclerosis and amyotropic lateral cyclerosis. We will discuss each disorder in detail with main emphasis on the molecular mechanisms of the disease in our future video. So please stay tuned to the channel. Alright, with this note I conclude this presentation and I hope the video was helpful for you to understand the basics of nervous system. If you liked the video please hit the like button. I will see you in the next video where I will bring similar kinds of topic related to the nervous system. If you haven't subscribed to the channel then please do subscribe to the channel and show your support. Your subscription makes a huge difference and motivates me to provide cost free education to everyone around the world. Thank you and take care.