HSCI 100 Lecture Notes - Lecture 13: Central Nervous System, Myelin, Leukodystrophy

• School: Simon Fraser University
• Department: Health Sciences
• Course: HSCI 100
• Professor: Mark Lechner

Document Summary

Nervous system: allows for rapid communication between cells through sensory input, integration of that input and commanding output in essence, homeostasis stimulated, it tends to atrophy and die. The more you use it, the stronger it becomes. Ions (charged molecules) moving inside and outside the cell. The ion flux is a signal, that triggers more ion flux. Initial signal flows from a source to all directions. All or none" phenomenon based on positive feedback mechanism. Action potential rapid change in the axon membrane ion balance that allows a nerve impulse to occur. The initial trigger may be a chemical signal or a voltage change (ion flux) Happens in a all or none" fashion; need to exceed threshold. First, sodium gates open letting na+ in > depolarization occurs. Interior of axon loses its net negative charge (goes up to about +40mv) Then, potassium gates open letting k+ out > repolarization occurs.