Neurons or nerve cells are the structural and functional units of nervous system. A typical neuron has three components: cell body or cyton, dendrons or dendrites and axon.
Cell body is the broader, round polygonal or stellate part which contains nucleus and various cell organelles. Cell body bears shot branched process called dendrites. Dendrites possess Nissl granules, neurofibrils, smooth endoplasmic reticulum, mitochondria, and Golgi vesicles.
Dendrites transmit impulses from synapses to the cell body.
Axon is long process which develops from a conical prolongation of cyton called axon hillock. Cytoplasm of axon called axoplasm. It is devoid of Nissl granules and Golgi components. Axon branched distantly. Axon carries the impulse away from the cell body.
Axon vs Dendrites
Axon
|
Dendrites
|
| Single per neuron | Usually many per neuron. |
| Arises from a conical projection, the axon hillock, from the discharging end of neuron. | Arises directly from the receiving surface of the neuron. |
| Very long (may be several metres) and of uniform diameter (0.25 - over 10mm) | Very short (generally under 1.5mm) and tapering. |
| Branched at the distal end only. | Much branched, practically all along. |
| Terminal branches enlarged to form synaptic knobs at the tips | No knobs at the tips of the branches. |
| Have neurotransmitter containing vesicles in the knobs. | Do not have such vesicles anywhere. |
| Axon carries the impulse away from the cell body. | Dendrites transmit impulses from synapses to the cell body (Cyton). |