生理学教学课件：Chapter 10 Neurophysiology.ppt

??Chapter 10 Neurophysiology ??? 1. Principles of neurophysiologyThe function of neurons Synaptic transmission 2. The functions of nervous systemSensory functionRegulation of posture and movementRegulation of visceral functionAdvanced function Part 1. The function of neuron and glial cellNeuron(1) The types of neurons: Afferent, efferent and interneuron (2) The function of neurondendriteCell bodyaxonterminalInitial segmentReceiving partAPConduction of APTransmitter release (3) The conduction function of nerve fiber In unmyelinated fibers local current in the excited site is inward and in unexcited site is outward, The outward current produces depolarization, leading to excitation In myelinated fiber, because of high resistance of myelin sheath, local current conducts across the nodes of Ranvier, named saltatory conduction Mechanisms of conduction --local excitation Properties of conduction in nerve fiberstructural and functional intactinsulating bi-directional not easy to be fatiguedConduction velocity is affected byV (m/s)≈6*Φ(μm) Φ(axon): Φ(total)=0.6Temperature (4) Classification of nerve fibers?Erlanger /Gasser classification of nerve fibers, according to electrophysiological properties Lloyd/Hunt classification of nerve fibers, according to diameter and origin Fiber typesFunctionAvg. fiber diameters (μm)Avg. cond. Velocity (m/s)AαPrimary muscle spindle afferents, motor to skeletal muscle15100 (70-120)AβCutaneous touch and pressure afferents850 (30-70)Aγmotor to muscle spindle520 (15-30)AδCutaneous temperature and pain afferents315 (12-30)BSympathetic preganglionic37 (3-15)CCutaneous pain afferents, sympathetic postganglionic fiber 11 (02-2)Erlanger /Gasser classification of nerve fibers GroupFunctionAvg. fiber diameters (μm)Avg. cond. Velocity (m/s)IIa: Primary muscle spindle afferents Ib: Afferents from tendon organs1375 (70-120)II?Cutaneous mechanoreceptors?955 (25-70)III?Deep pressure sensors in muscle?311(10-25)IVUnmyelinated pain fibers11Lloyd/H