Nerve impulse in myelinated axon. Animation illustrating the propagation of a nerve impulse along an axon with a myelin sheath (light blue). The animation starts with an illustration across top of a nerve fibre (axon) connecting a nerve cell body (purple, top left) and the axon terminal (branched, top right). The myelin sheath is divided into segments, with the gap between segments known as a node of Ranvier. The myelin sheath acts as an electric insulator preventing ion transfer between the axon and the external environment. The animation continues with a box and arrow (upper centre) showing the area at bottom magnified from the inset. The animation across bottom shows three segments of myelin sheath and ion channels (green and blue) at four nodes of Ranvier. The nerve impulse (action potential) starts at left, with an influx of sodium ions (red) through sodium ion channels (blue). The nerve impulse (arrows) travels along the axon to the next node of Ranvier, where it activates the sodium ion channels and an influx of more sodium ions propagates the action potential along the axon. This continues along each segment, with the potassium channels (green) activating in the wake of the action potential and potassium ions (light blue) flowing out at the nodes. The conduction velocity of the nerve impulse (jumping from node to node) is greater than if the myelin was not present. For this animation with labels, see K004/2038. | |
Licence : | Droits gérés |
Crédit : | Science Photo Library / Biocosmos / Francis Leroy & Michael Pierard |
Model Release : | Non requis |
Durée : | 35 Secondes |
Aspect ratio : | 16/9 |
Restrictions : | - |