Dendrites

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A Dendrite is an extension of the cell body from a neuronal cell, this the place in a neuronal cell where it receives communication from other neuronal cells and where it is determined whether or not an action potential is transmitted down the axon [1]. In a dendrite when neurotransmitters cross the synaptic cleft and bind to receptors on the membrane a signal is transferred, unlike in the axon of a neuronal cell the signal is not an action and in fact a graded potential. The graded potential can be of varying strengths and depending on the strength of the graded potential when it reaches the axon hillock if the graded potentials exceed the threshold level then an action potential is sent down the axon. There are two types of graded potentials, one is excitatory and the other is inhibitory. The excitorary potential is known as an EPSP, this is initiated by Na+ ion channel opening and the entering of Na+ ions into the cell depolarising the membrane potential, the inhibitory potential, the IPSP is initiated by the Cl- ion channel opening and this hyperpolarises the membrane potential and will as a result cancel out an EPSP and inhibit a action potential being produced.

References

  1. Alberts et al., 5th edition, G:10
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