Dendrite

Structure of a classic neuron.

The dendrites (from the gr. δένδρον déndron «tree») are quite short, branched protoplasmic extensions of the neuron, dedicated mainly to the reception of stimuli and, secondarily, to cell nutrition. They are terminals of neurons; and serve as receptors for nerve impulses coming from an axon belonging to another neuron. Its main function is to receive impulses from other neurons and send them to the soma of the neuron.

Dendrites arise as numerous, branching processes from the cell body. In spinal sensory neurons, however, a long axon is interposed between the dendrites and the perikaryon. Along the dendrites are dendritic spines, small cytoplasmic processes, which are sites of synapses. The cytoplasm of the dendrites contains mitochondria, membranous vesicles, microtubules, and neurofilaments.

They have chemoreceptors capable of reacting with the neurotransmitters sent from the synaptic vesicles of the presynaptic neuron, being essential for the correct transmission of chemoelectric impulses through the nervous pathway.

Nerve conduction

The dendritic tree, together with the perikaryon, constitute receptive parts of the cell; and are essential in the transmission of the nerve impulse. This is because, in response to stimulation by other cells, the membrane potential of an excitable cell depolarizes. It is precisely when this potential depolarizes beyond a certain threshold that an action potential is triggered, which propagates through the membrane, attenuating as it moves away from the excited point. Dendrites have dendritic spines, small extensions that increase the surface area and are responsible for receiving information. The atrophy or deficient development of these spines is related to cognitive deficits, in particular, their inadequate formation is associated with syndromes such as trisomy 21.