PSY290H5 Chapter Notes - Chapter 4: Axon Hillock, Golgi Apparatus, Resting Potential
Document Summary
4. 3 integration of postsynaptic potentials and generation of action potentials: It was once believed that action potentials were generated at the axon hillock (conical structure at the junction between the cell body and the axon) Most neurons receive thousands of such contacts. Some neurons have a mechanism for amplifying dendritic signals that originated far from their axon initial segments. The random movement of ions rapidly reestablishes resting membrane potential: the na+/k+ pump only plays a minor role of this reestablishment. The refractory period is responsible for two important characteristics of neural activity: responsible for unidirectional action potential propagation, responsible for intensity-dependent neural stimulation. Multiple sclerosis damages the nervous system by attacking myelin. The speed depends on two properties: diameter and myelination. The larger the diameter the faster it will conduct. Myelinated motor neurons can conduct speeds of 100m/s and small, unmeylinated axons conduct action potentials of about 1m/s. Maximum velocity of conduction in human motor neurons is about 60 m/s.
