Types of neurons, Biology

TYPES OF NEURONS -

The neurons are classified on the basis of their structure and function.

(A) On the basis of the structure, the neurons are of four types.

(i)      Nonpolar or Unpolarized Neurons - Each neuron bears several branched processes. There is no functional difference between dendrites and axon. Each process can bring an impulse to the cyton, or can take it away from the cyton. e.g. cnidarians (= coelenterates) such as Hydra.

(ii)     Unipolar Neurons. Each neuron has a single process. The process divides into two further processes. One is axon and the other is a dendrite. This neuron is described as unipolar, but from a functional point of view it is to be regarded as bipolar. e.g. Most sensory neurons are unipolar. They occur in the dorsal root ganglia of spinal nerves and granule cells of olfactory bulbs (part of olfactory lobes of the brain).

(iii)     Bipolar Neurons. These neurons have only two processes, an axon at one end and a dendrite at another end.

Bipolar neurons are found in the retina of eyes, olfactory epithelium and cochlear and vestibular ganglia (cochlea and vestibule are the parts of membranous labyrinth of internal ear).

(iv)      Multipolar Neurons. These neurons have several dendrites and an axon. Motor neurons and interneurons are multipolar. They are the most common type of neurons. Multipolar neurons occur in the grey matter of the brain and spinal cord.

 

(B) On the basis of function, neurons are of three types.

(i)     Sensory (= Receptor or Afferent) Neurons. They connect sense organs with the central nervous system (brain and spinal cord). They bring sensory impulse from sense organs to the central nervous system.

(ii)     Motor (= Effector or Efferent) Neurons. They connect the central nervous system to the effectors (muscles and glands). They carry motor impulses from the central nervous system to the effectors.

(iii)    Interneurons (= Connector, Relaying Or Adjustor Neurons). They are present in the central nervous system and occur between the sensory and motor neurons for distant transmission of impulses. They are neither sensory nor motor.

Posted Date: 10/1/2012 4:17:12 AM | Location : United States







Related Discussions:- Types of neurons, Assignment Help, Ask Question on Types of neurons, Get Answer, Expert's Help, Types of neurons Discussions

Write discussion on Types of neurons
Your posts are moderated
Related Questions
Length of the Implant Used The length of the implant to be used is dictated by the available bone height. The success rate is proportional to the implant length and the quality

Ethidium Bromide  intercalates within structure of the nucleic acids in such a manner that they fluoresce under the UV light. Ethidium bromide staining is generally used to visuali

Determine the Procedure of Armamentarium 1. Make an impression of the mandibular ridge and pour the cast in type 3 gypsum 2. Apply separating medium and allow it to dry 3

Which of the following statements least accurately explains our knowledge of how gene number relates to "organismal complexity"? A. Based on known gene numbers there appears to

The overall goal of BCC programs for diabetes mellitus is to promote behaviors that control diabetes mellitus and prevent complications. These include: Following treatment

If the generation time (t) is the incubation time (t) per generation (G), or t = t/G, rewrite the formula you derived in question 2 for bacterial population growth in terms of incu

1. Write general characters of phylum mollusca and classify it upto classes, giving at least two examples of each class.

Thus, the objectives of the nutritional care process should include the following points: 1. Restoration of good nutritional status with dietary modifications and counseling.

Give the results of DistaE Dissection ? Results :  For acute dissection of different parts of aorta, the mortality is reported as 9 to 33 per cent. In the International Regis

Define Hormonal and Receptor Proteins? Hormonal proteins : Hormonal proteins coordinate the bodily activities. Several peptide and protein hormones (like insulin and growth ho