Biology Times (^19)
July
passes to the post-synaptic neuron or an
effector cell.
In most neurons, the plasma membrane
of the dendrites and cell body contains
protein receptors that receive signals from
other neurons. Therefore, the dendrites and
cell body are the neuron’s input zone. The
axon hillock is the neuron’s trigger zone,
because it is the site where action potentials
are triggered, or initiated. Functionally, the
axon is the conducting zone of the neuron,
as action potentials are then conducted along
the axon. The axon terminals constitute its
output zone because they release a
neurotransmitter that stimulates other
neurons or effectors cells close to them.
Ion Channels
Because the water-soluble ions responsible
for carrying charge cannot penetrate the
plasma membrane’s lipid bilayer, these
charges can cross the membrane only through
specific ion channels. Ion channels are
membrane proteins that form pores through
the membrane, allowing diffusion of specific
ions across the membrane. Various types of
ion channels are listed in the above table.Resting Membrane potential
Membrane potential is similar to the electrical
potential difference that exists between
the two poles of a battery. In a battery, one
pole is positive, and the other is negative.
Similarly, a potential difference exists across
every cell’s plasma membrane.The side of
the membrane exposed to the cytoplasm is
the negative pole, and the side exposed to the
extracellular fluid is the positive pole.
Why is the cell membrane polarised?
Like all cell membranes, the plasma membrane
of a neuron acts as a barrier that separates
charges. As already stated, water-soluble