The Central Nervous System

Keywords

Brain, nerves, spinal cord, electrical impulses, receptors, effectors, stimuli, response, autonomous, reflex arc.

Introduction

When you place your hand over a hot flame (say for instance, a candle) and hold it there, what happens? At some point in the near future, you're going to have to take your hand away for it being too hot to handle. This is a motion that requires your central nervous system.

How Does it Work?

Your brain is connected to almost every part of your body, through a network known as the central nervous system. Within this system, electrical impulses tells parts of your body to move, like the fingers typing up this piece of text. My brain is telling my fingers where to move on a standard keyboard layout, and my fingers are reacting to the nerve impulses to type.

Interesting fact: wrinkles in the brain are an evolutionary trait - folds allow more brain matter to fit in the skull without increasing the skull's size.

A closer look at this is needed.

Organs Included

The brain
The spinal cord
Nerves

Much like the other systems in our body, it covers all parts of it. The nerves and endings all react to what the brain tells it to do. This itself is managed by electrical impulses through nerve cells.

Here is a YouTube video from Cognito on the CNS and reflex arc:

Run me Through a Scenario (Reflex Arc)

So, back to the candle. Your brain has told your hand to move and place itself just above the candle flame. Inside you, there's an electrical impulse that travels from your brain, down a network of synaptic pathways to the parts of your body that you end up moving (for this instance, your arm and hand).

When it gets too hot, receptorsThe end of a nerve that changes to an electric impulse. in your hand (I'm assuming that's the part you've placed over the flame, and not your arm - hey, don't argue with me!) tell your brain that something is getting hot, and that you need to move your hand out of the way. A signal is sent from the area of your hand to your brain asking for permission to move. The brain accepts defeat and then moves the arm on its behalf, using effectorsThe muscle reacting to the stimuli.. These are the muscle or gland responses that move your arm away from the flame.

The heat from the candle is the stimuli in this instance.

The movement away from the heat is the response your brain will message down to the hand.

This is all done autonomously, and also at lightning speed - I mean, how fast does electricity travel down a wire; ever tried disconnecting your phone from the wire when on charge, turning off the power supply and reconnecting your phone. You get a millisecond of power charge from the wire. The same things happen with your brain and central nervous system.

Interaction with the Ear

Often you may find that you lose your balance. This could be because of clumsiness, but could also be an imbalance of the ear. But how does that affect you, and what links it to the central nervous system?

Well, your ear is made up of a series of parts:

The outer ear
The middle ear
The inner ear

The Outer Ear

This is the visible part of your ear. The ear lobe (the flabby part at the bottom where some of you may have earrings), and the auricle (also known as the pinna). Depending how your genetic makeup is, your ears can have many different shapes and sizes, but they still work the same.

The external auditory canal is the tubular device of the ear that travels inside your head. This is closed off by a tympanic membraneMore commonly known as the eardrum.. The idea of the outer ear is to collect sound waves as they move through the air. They are then guided to the tympanic membrane.

The Middle Ear

Inside the ear, further than the tympanic membrane, there are a series of three bones - the malleus (hammer), incus (anvil) and stapes (stirrup). Together they form the auditory ossicles.

The Inner Ear

Inside the inner ear are two functional units - the vestibular apparatus, which contains the sensory organs for your postural equilibrium - this means it helps you stand up straight and maintain your balance. The other part is the snail-shell-like cochlea, which is the sensory organ of hearing. Without this, you wouldn't be able to hear. From there, the ear turns into nerves that link with your brain.

Hearing Deficciencies

You can have a certain amount of deafness in one or both ears. If you have a hearing deficciency, it can be treated. There are implants you can have put in your ear, and also hearing aids that can help you hear properly.

Too Long; Didn't Read

The central nervous system controls many components of our body. It is run by the brain, which sends out electrical impulses to extremities of the body, like our fingers, where they then move.

The system is protected by the skull and the spine, where the spinal cord runs down the back of the body.

For example, when you have you hand above a naked flame, your brain will tell your hand to move when it gets too hot. This is all done by electrical impulse down a series of nerve cells that link together, and enable very fast communication to parts of the body.