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Nerve Impulses & The Eye Essay

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Below is an essay on "Nerve Impulses & The Eye" from Anti Essays, your source for research papers, essays, and term paper examples.

Sensory nerve- carries electrical message from receptor to spine

Sensory nerve- carries electrical message from receptor to spine

Nerve Impulses
Nerve Impulses
Motor nerve- carries electrical message from spine to effector
Relay nerve- connects sensory and motor nerves. Also relays message to the brain.
Schwann cells- wrap around the axon of the long nerves, creating a thick layer of membrane, which insulates the nerve and allows for much faster conduction speed. The thick layer of membrane has gaps in it between adjacent Schwann cells; these are called Nodes of Ranvier.

Motor nerve- carries electrical message from spine to effector
Relay nerve- connects sensory and motor nerves. Also relays message to the brain.
Schwann cells- wrap around the axon of the long nerves, creating a thick layer of membrane, which insulates the nerve and allows for much faster conduction speed. The thick layer of membrane has gaps in it between adjacent Schwann cells; these are called Nodes of Ranvier.

Voltage-Gated K+ Channels open
Voltage-Gated K+ Channels open

Voltage-Gated Na+ Channels open

Voltage-Gated Na+ Channels open

A synapse is the junction between two nerves.
  * 1. The wave of depolarisation arrives at the synaptic knob. The membrane in the presynaptic neuron is depolarised to –50mv (threshold potential) and the voltage-gated Na+ channels open, letting Na+ into the cell.
  * 2. The membrane is depolarised to +30mV and voltage-gated K+ channels open. The membrane potential falls to –90mV and the cell goes into its refractory period, where the 3Na+/2K+-ATPase restored the ion concentrations.
  * 3. Unlike axons, presynaptic nerves also contain a Voltage-gated Ca2+ channel. As the presynapstic membrane depolarises these channels open and let Ca2+ into the cell.
  * 4. The Ca2+ causes vesicles in the presynaptic nerve to migrate and fuse with the presynaptic membrane, where they spill neurotransmitter chemical into the synaptic cleft....

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