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• 1. EXCITATORY: cause DEpolaristion
• -Acetylcholine (ACh)- at nerve-muscle synapse-stimulus gated Na+ channels
• -Glutamate- at all excitatory synapses in brain
• *Thus -EPSP's ( Excitatory Post Synaptic Potentials)

• 2. INHIBITORY:cause HYPERpolarisation-
• -GABA (gamma amino butyric acid)
• *thus, IPSP (Inhibitory post synaptic potential)
• 

• 1. Spatial summation:effect produced by simultaneous stimulation by a few
• synaptic knobs on the SAME postsynaptic neuron

2. Temporal summation:produced by rapid sucession of stimuli on a SINGLE postsynaptic neuron.

3: Inhibitory & Excitatory summation: produces potential at axon hillock. (many synaptic knobs)

• 1. Divergent-info. from eg. a single sensory neuron may DIVERGE to arrive at DIFFERENT brain regions
• *THUS-amplify signals
• -control points

• 2. Convergent- info. from DIFF. brain regions may CONVERGE on a SINGLE motorneurone that excites a SINGLE muscle group
• -Redundancy- inelectronics (provides alternatives in case one fails)
• -Control points