Neurons - axon hillock. The cytoplasm of the axon, the...

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Neurons A neuron is a cell that transmits nerve impulses. It consists of the following parts, shown in Figure 1:  The cell body (soma or perikaryon) contains the nucleus and other cell organelles. There are clusters of rough endoplasmic reticulum (not shown in Figure 1) that are  called Nissl bodies or are sometimes referred to as chromatophilic substances.  The dendrite is typically a short, abundantly branched, slender process (extension) of  the cell body that receives stimuli. The  axon  is typically a long, slender process of the cell body that sends nerve  impulses. It emerges from the cell body at the cone-shaped axon hillock. Nerve impulses  arise in the trigger zone, generally located in the initial segment, an area just outside the 
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Unformatted text preview: axon hillock. The cytoplasm of the axon, the axoplasm, is surrounded by its plasma membrane, the axolemma. A few axons branch along their lengths to form axon collaterals, and these branches may return to merge with the main axon. At its end, each axon or axon collateral usually forms numerous branches ( telodendria ), with most branches terminating in bulb-shaped structures called synaptic knobs (synaptic end bulbs, also called terminal boutons). The synaptic knobs contain neurotransmitters, chemicals that transmit nerve impulses to a muscle or another neuron....
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