Myelinated fibre, Biology

Myelinated fibre

Axon is a relatively long process (also quite often referred to as nerve fibre) and can be considered as functionally specialised for conduction of excitation over considerable distances. In vertebrates the axons of high velocity neurons are covered by insulating sheaths of lipid containing myelin. This myelin is made up of special glial cells -the Schwann cells. The myelin covering is not continuous. There are tiny uninsulated gaps between adjacent Schwann cells. These are the-nodes of Ranvier. The myelin covering and nodes of Ranvier help accelerate the speed of conduction of impulses by a mechanism which we will discuss later. The terminal part of the axon branches, terminating into small ramifications whose tips form end knobs which synaptically contact with other nerve cells. In the end knobs are present characteristic structures called synaptic vesicles which contain and store chemical substances called neurotransmitters.

349_Myelinated fibre.png

Figure: Myelinated fibre

The diversity in neuron form, however so much that is there can be many variations from the generalized description given above. For example, the nerve cells called amacrine cells found in retina contain processes without a demonstrable axon.

Posted Date: 1/17/2013 12:16:44 AM | Location : United States







Related Discussions:- Myelinated fibre, Assignment Help, Ask Question on Myelinated fibre, Get Answer, Expert's Help, Myelinated fibre Discussions

Write discussion on Myelinated fibre
Your posts are moderated
Related Questions
Chronic Aortic Regurgitation :  The aetiological factors leading to aortic regurgitation are: (1) rheumatic, (2) annulo aortic ectasia, (3) native valve endocarditis, (4) c

Fructose-1,6-bisphosphate  and Fructose-6-phosphate : The  conversion of  fructose-1,6- bisphosphate  to fructose-6-phosphate is  catalysed by fluctose-1,6-bisphosphatase  which  i

Aetiology:   A List Of The Causes Of A Disease  (Description Of The Characteristic Causes) Factors Which Influence The Onset Of Disease:  Include "Risk Factors", Life-Style, Sex, A


Define Counseling and compliance for celiac disease? If symptoms do not improve, the child's diet should be reviewed and evaluated. A decrease in diarrhoea, increase in height

What is Physical activity ratio? Physical activity ratio (PAR): The energy cost of an activity per unit of time (usually a minute or an hour) expressed as a multiple of BMR. It

Classification of Living Organisms – Species You have by now already come across the word 'species'. The word has a definite meaning in biology. Although the living world is v

Define about the Micro Minerals? Micro minerals are those minerals, which comprise less than 0.01% of the total body weight and are required in concentrations of one part per m

Describe in detail about the Cytoplasm Cytoplasm also possesses a number of dense granular elements (about 25,000 per cell) called the ribosomes, which are the sites of protein

How Pathologic Conditions causing the underweight? Illness can affect weight status in a number of ways. For example, fevers and infections increase the demand for energy, whic