ArtsAutosBooksBusinessEducationEntertainmentFamilyFashionFoodGamesGenderHealthHolidaysHomeHubPagesPersonal FinancePetsPoliticsReligionSportsTechnologyTravel

Human Nervous System

Updated on July 4, 2015

"Do you have a brain?" We often ask this question to our friends who say something or act in a way of ignorance. "I am nervous". We say this in the fear of exams. "ouch" we scream and take off our hand when something sharp pricks it. Do you know that all this happens due to the nervous system, which has a wonderful networking system? Lets see some important things regarding this system.
The nervous system enables us to feel, think, move, hear, see etc. It controls body activities. It establishes co-ordination between different organs of the body. Nervous system is divided into 3 divisions, which inturn have their components.

Source
Source

You learn about central and peripheral nervous systems in this lesson.
Nervous system can sense the changes inside and outside the body. The nervous impulses are in the form of small electrical currents. Nervous system is made up of neurons and glial cells.
Neurons: These are the functional units which receive and process information and generate responses. Cyton, axon and dendrites are the different parts of a neuron.

Cyton or perikarya has a large neucleus and the cell body has nissile granules, axon otherwise called as nerve fibre is a projection from the cell body. The corners of the cell are drawn into a number of branched threads called dendrites. They form synapses with the dendrites or axons of other cells.
Synapse: It is the junctional place between two neurons. Dendrites of one axon lie in close association with dendrites of another axon.
Action Potential: The electric potential generated between axon and cell body is called action potential or nerve impulse.

Source

Types of Nerves in Human Body:

Efferent (outgoing) Nerves: These carry impulses from brain to spinal cord or effector organs. They are also called motor nerves (movement of hand and legs).
Afferent (incoming) Nerves: These carry information from the sense organs to specific areas in brain and spinal cord. They are also called sensory nerves (ears, nose, tongue, eyes, skin etc).
Mixed Nerves: These have both motor and sensory nerve fibres.
Central Nervous System
Brain:It consists of two parts. The brain located in the skull and the spinal cord located in the vertebral column. It is a very soft tissue and is surrounded by a bony case called cranium, which protects the brain from injuries. The brain is covered by three membranes. A fluid called cerebro-spinal fluid flows in between the outer and middle membranes, which also protects it from injuries.
The weight of the average human brain triples between birth and adulthood. The final weight in an adult male is 1.4 kg and in female is 1.3 kg. It is about 3% of the body weight. It uses about 20% of the oxygen a man breathes, 20% of calories a man takes in and about 15% of body blood.

Source

The brain consists of:

(i) Cerebrum: It is the largest part of the brain consisting of two hemispheres which control voluntary actions and are the seat of intelligence, memory association, imagination and will. The cerebral cortex consists of several ridges called 'gyri' and the grooves called 'sulci', which increase its surface to accommodate more number of neurons.
(ii) Cerebellum: The large mass with grey matter on the surface and white matter in the deeper layers. It controls all the voluntary movements of the body. It is responsible for the maintainance of equilibrium and posture of the body.
(iii) Medulla Oblongata: The lower most part of the brain which controls involuntary actions. It continues as the spinal cord in the vertebral column.
Spinal cord: It is the extention of medulla oblongata. It is concerned with reflex actions. From the spinal cord arise 31 pairs of spinal nerves. it acts as a relay station by receiving and sending information from body parts to brain and viceversa.

Peripheral Nervous System:

It consists of cranial nerves and spinal nerves.
Cranial nerves: 12 Pairs of these nerves take their origin from different areas of brain. Some of these nerves ae sensory. Some are motor and a few are mixed nerves. Branches of these nerves go to the retina, ear, nose, tongue, eye, muscles, face, neck and pharynx. Of these nerves, vagus is more important as it controls the rate of heart beat and secretions of pancreas.
Spinal nerves: 31 pairs of these nerves originate from spinal cord, which are mixed nerves.

The sensory fibres originate from the dorsal horn of the spinal cord, which carry information from sensory organs to spinal cord. The motor fibres take their origin from the ventral horn of the spinal cord, which supply information required for the movement of muscles.

Reflex Action and Reflex Arc:
Reflex Action: Simply called as reflexes are very important as they save us from painful and dangerous stimuli. They are fast, immediate; automatic and involuntary. These are 2 types.
Unconditional reflexes: These are inborn, not learnt and same in all individuals and animals.
Eg: Withdrawing our hand when we touch a hot object.
Conditional Reflexes: These are learnt by doing same actions many times.
Eg: standing in attention when hearing National Anthem.
Reflex Arc: It is the structural and functional unit that carries out the reflex actions. It consists of a receptor, a sensory nerve, an association neuron, motor nerve and an effector organ which carry the whole process of receiving information and generating electrical responses.

Human Nervous System

Comments

    0 of 8192 characters used
    Post Comment

    No comments yet.

    working

    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, hubpages.com uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

    For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at: https://hubpages.com/privacy-policy#gdpr

    Show Details
    Necessary
    HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
    LoginThis is necessary to sign in to the HubPages Service.
    Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
    AkismetThis is used to detect comment spam. (Privacy Policy)
    HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
    HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
    Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
    CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
    Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the googleapis.com or gstatic.com domains, for performance and efficiency reasons. (Privacy Policy)
    Features
    Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
    Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
    Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
    Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
    Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
    VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
    PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
    Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
    MavenThis supports the Maven widget and search functionality. (Privacy Policy)
    Marketing
    Google AdSenseThis is an ad network. (Privacy Policy)
    Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
    Index ExchangeThis is an ad network. (Privacy Policy)
    SovrnThis is an ad network. (Privacy Policy)
    Facebook AdsThis is an ad network. (Privacy Policy)
    Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
    AppNexusThis is an ad network. (Privacy Policy)
    OpenxThis is an ad network. (Privacy Policy)
    Rubicon ProjectThis is an ad network. (Privacy Policy)
    TripleLiftThis is an ad network. (Privacy Policy)
    Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
    Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
    Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
    Statistics
    Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
    ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
    Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)