2 Fun facts about neurons Most specialized cell in animalsLongest cell:blue whale neuron10-30 metersgiraffe axon5 metershuman neuron1-2 metersNervous system allows for 1 millisecond response time
3 3 parts of a NeuronDendrite – branched end that extends out from the cell, provides a large surface area to receive nervous informationCell Body – control center, regular cell organelles (nucleus etc)Axon – long thin fiber, extends out from cell body, carries action potential from cell body-ending are called synaptic terminals
4 Nervous system cells Neuron Structure and function a nerve cell signaldirectiondendritescell bodyStructure and functionmany entry points for signalone path outtransmits signalaxonsignal directionsynapsedendrite cell body axon
5 3 Types of Neurons Motor – connects to a muscle or gland Sensory – receives a stimulusInterneuron – connects the above 2
12 Reflex Arc A motor, sensory and inter neuron form a reflex arc Begins with a stimulus causing an impulse in the sensory receptors of a sensory neuron.The impulse then continues on through the dendrite, cell body and axon of a sensory neuron (DCA).
13 The impulse passes to the interneuron, passing through dendrite, cell body and axon (DCA). The impulse passes onto the motor neuron, passing through the dendrite, cell body, and axon (DCA).This causes a response in an effector (a muscle or a gland)
16 Nerves Combination of nerve cell fibers Sensory dendrites and motor axons
17 Summary Neuron Types Sensory Neuron Interneuron Motor Structure Long dendriteShort axonShort dendriteLong axonFunctionConduct impulse to cordInterconnect sensory neurons with motor neuronsConduct impulse to effector (muscle/ gland)LocationCell body/ dendrite outside spinal cordCell body- dorsal rootEntirely within CNSCell body/ dendrites in spinal cordAxon outside spinal cord
18 Synapses/ synaptic gap Synapse- region of close proximitySynaptic gap- Space between a neuron (axon terminal) and the next cellThe next cell could be another neuron or an effector (muscle/ gland)Space between must be bridged by neurotransmittersMore on neurotransmission and nerve impulses tomorrow!