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

Conduction system of the heart, Structure of the Conduction System of the H...

Structure of the Conduction System of the Heart Sinoatrial (SA) Node is the pacemaker node located in the right atrium near the opening of superior venacava. It is called

Therapeutic dose of pyridoxine, Q. Therapeutic dose of pyridoxine? Ther...

Q. Therapeutic dose of pyridoxine? Therapeutic dose of pyridoxine (lg/day) is usually tried in all patients with hypermethioninernia and homocystinemia. For patients who do not

Pathophysiology and assessment of patent ductus arteriosus, Pathophysiology...

Pathophysiology   If  the ductus arteriosus does not close after birth, the higher pressure in the aorta than in the pulmonary artery causes the blood to flow from the aorta, t

Where do the photochemical stages of photosynthesis occur, Where do the pho...

Where do the photochemical and the chemical stages of photosynthesis occur? The photochemical stage of the photosynthesis process happens mainly on the thylakoids (the green pa

Define class cephalopoda in animal kingdom, Define Class Cephalopoda in ani...

Define Class Cephalopoda in animal kingdom? This group-including squids, octopuses, and the nautilus-is considered by most scientists to have the highest intelligence among all

Show the energy pyramids, Q. Can the amount of available energy in a given ...

Q. Can the amount of available energy in a given trophic level be larger than the available energy in inferior trophic levels? What does that condition means to the conformation of

Explain epitope, Epitope: As related to the protein antigens, B-cell epito...

Epitope: As related to the protein antigens, B-cell epitopes comprises the amino acid residues of the protein molecule in which interact directly through the noncovalent bonds wit

Learning objectives of coronary artery disease, Q. Learning objectives of c...

Q. Learning objectives of coronary artery disease? • describe the various forms of coronary heart diseases, • enumerate the risk Factors (genetic and environmental) in causati

Describe the term - ambulacral groove, Describe the term - Ambulacral groov...

Describe the term - Ambulacral groove The groove that runs down the oral surface of each echinoderm arm and contain the tube feet. If the region contains a visible furrow, or gr

Explain phylum zygomycetes, Phylum Zygomycetes 1) Asexual reproduction ...

Phylum Zygomycetes 1) Asexual reproduction by non-motile spores produced from a stalked spore case which is known as sporangium. 2) They reproduced by- conjugation between n

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