Conduction in myelinated axons, Biology

Assignment Help:

Conduction in Myelinated Axons

The myelin sheath provides insulation for the axon preventing movements of Na+ and K+ through the membrane. Therefore, if this myelin sheath was continuous no action potential would be generated. Fortunately, gaps or nodes of Ranvier occur in the myelin. Since the cable properties of axon can conduct depolarisations over very short distance (1-2 mm), the nodes of Ranvier must be close together (actually they are 1 mm apart). Studies have shown that the Na+ channels are concentrated at the nodes and absent from the regions between two nodes. Action potential therefore occurs only at the nodes of Ranvier and seems to leap from node to node. This is called saltatory conduction. The spread of depolarisation between the nodes is very fast and fewer action potentials are needed. Therefore, the rate of conduction is much faster than in unmyelinated fibres.

This peculiar structure and mode of conduction in myelinated fibres is responsible for the fast conduction of impulses in motor nerves of vertebrates even though the nerves are very thin. The greatest advantage of myelinated fibres comes from their smaller size and so a highly complex nervous system with high conduction velocities can occur without occupying too much of space.


Related Discussions:- Conduction in myelinated axons

Oogenesis, in human and mammals how many cells result from oogenesis

in human and mammals how many cells result from oogenesis

Illustrate sulfur photosynthetic bacteria, Q. What is the molecule that don...

Q. What is the molecule that donates hydrogen for photosynthesis, in sulfur photosynthetic bacteria? In sulfur photosynthetic bacteria the substance that donates hydrogen is hy

Define techniques for detection hidden root canals, Define Techniques for D...

Define Techniques for Detection Hidden Root Canals Three well-angulated periapical films for 3D morphology: o With the cone directed straight on. o Mesiobilque. o And disto

Define essentiality of carbon for growth of micro-organism, Define the Esse...

Define the Essentiality of Carbon for the Growth of Microorganisms Carbon is needed for the skeleton of all organic molecules. Microorganisms acquire it either as inorganic car

Explain about the infantile beriberi, Explain about the Infantile beriberi?...

Explain about the Infantile beriberi? Infantile beriberi is commonly seen in many South-East Asian countries where the diets consist mostly of "polished rice" and are deficient

Why is photosynthesis referred to as a biochemical pathway, a) Why is it si...

a) Why is it significant that ions being transported across a cell membrane be shielded from the interior of the lipid bilayer? b) Why is photosynthesis referred to as

Define the buffer capacity - nutritional biochemistry, Define the Buffer ca...

Define the Buffer capacity - Nutritional Biochemistry? Buffer capacity can be defined as, 'the capacity of a solution to resist changes in pH on the addition of strong acid or

What are holandric genes, What are holandric genes? The Holandric genes...

What are holandric genes? The Holandric genes are genes situated in the nonhomologous region of the Y chromosome. Holandric genes condition phenotypes that emerge only in men s

Procedures adopted by numerical taxonomists, Q. Procedures Adopted by Numer...

Q. Procedures Adopted by Numerical Taxonomists? Since numerical taxonomy is an operational science, the procedure is divided into a number of repeatable steps, allowing the res

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd