Functional unit of the nervous system-neuron, Science

Functional unit of the nervous system-neuron:

The human brain is composed of more than one hundred billion (100,000,000,000  or 1011) cells called  'neurons'. This number which  is comparable  to the number of stars  in the Milky Way, gives us an idea about the size of the neurons also  -  because 10"  of  them fit in a space which slightly more than a litre of water can occupy. Since these neurons are the functional units of the whole nervous system, let us become familiar with some of their basic features. You can see some typical neurons in Fig.

Neurons can be categorised  into the following kinds according to their functions : 

a) Motor neurons  :  send signals from the nervous system to muscles and glands.

b)  Sensory neurons :  carry signals from the receptor cells in  sense organs in the body to the nervous System. For example, signals generated by  touch or smell or hearing etc. 

c)  lnter neurons  or association neurons :  process the sensory  information received from other neurons,  and convey messages. For example, when an  insect bites, the fingers are given a command  to~cratch  at ,  that point. Most of  the brain's neurons fall in this category. 

The neurons are specialised to carry iqformation from one part of the body to another. These messages are referted to as nerve  impulses. The nerve impulse occurs in response to some. stimulus  or  event which excites  them. Notice in fig that in every neuron,  fhe portion of the cell with the nucleus is called the cell body.

234_neuron.png

Posted Date: 9/28/2012 8:35:44 AM | Location : United States







Related Discussions:- Functional unit of the nervous system-neuron, Assignment Help, Ask Question on Functional unit of the nervous system-neuron, Get Answer, Expert's Help, Functional unit of the nervous system-neuron Discussions

Write discussion on Functional unit of the nervous system-neuron
Your posts are moderated
Related Questions
Forebrain: The largest part of  the brain that you  see in Fig. is the cerebrum. It consists of  two halves or hemispheres  joined  together by  a band of  nerve fibres. Intere

Define Proteins - Abnormal Constituents of Urine Proteins: Abnormal amounts of proteins are excreted in certain inflammatory diseases like glomerulonephritis (inflammation of t

Objectives : After studying this unit, you should be able to: 1.   List the obligations of the teachers and the Head of the institution towards 2.   Safe working conditions

Vitamin E  (Tocopherols) Vitamin E is an essential fat-soluble vitamin that functions, at  least in part, as a lipid- soluble antioxidant. Presence of vitamin E was first revea

why are insulators so hard to find

The physical property used in mineral identification for the way a minerals surface reflects light is known as  luster

what is ecology

Depletion of Ozone Layer: Since  the last decade or so, there is concern about the possible reduction in the ozone layer surrounding  the earth. Now the question arises, what h

WIRING A PLUG TO AN APPLIANCE In the previous activity, you worked out the operating current of different electrical equipment/appliances and suggested proper fuse and plug

Mr. X's medical history is fairly uncomplicated [...]. Family medical history is significant for [...].  Mr. X's verbal responses were very articulate, and he gave long, express