The electrical impulse in a nerve cell begins when ions move through the cells surface through ion channels.
The nerve impulse.
A nerve impulse is a wave of excitation that quickly travels within the surface of a neurone (nerve cell). This nerve impulse usually travels on certain parts of the nerve cell: on a dendrite or an axon. Within a neurone the first event depends on the type of 'nerve impulse'; there are two important types:
1- nerve impulses generated at dendrites
2- self propagating nerve impulses (action potentials) that travel along the axon
Nerve impulses generated at dendrites.
Dendrites feed into the 'cell body' (soma) of a neurone. Nerve impulses that are generated in these dendrites travel toward the cell body.
A sequence of events occur at the surface of a dendrite when the nerve impulse is sparked. The first event is transduction; this involves the transformation of one form of energy outside the dendrite into electrical energy within the dendrite.
Nerve impulses that travel along axons.
Nerve cells often have many dendrites but often only have a single axon. The essential difference between the two parts of the nerve cell is:
- in dendrites electrical impulses travel TOWARDS the cell body of the neurone
- in the axon the electrical impulses travel AWAY from the cell body of the neurone
The nerve impulse that travels along an axon begins at the 'base of the axon', where the cell body and axon merge. This site is called the 'axon hillock' and is found to be the site where the first event in the formation of a nerve impulse actually occurs. Again, the first event is transduction at the axon hillock.
Conclusion; the first event.
For both of the cases above, and for virtually any other case, the nerve impulse begins with a process of transduction. The electrical nerve impulse begins once the first 'ions' leave or enter the nerve cell. Usually sodium ions enter, sometimes calcium ions are the firs to enter, sometimes potassium ions are the first to leave.
sodium ions move to the inside of a neuron
The main events of a nerve impulse: resting potenial, depolarization, actiion potential, and polarization.
Action potential
A nerve impulse starts at the dendrite
A nerve impulse is approximately 1 millisecond.
What they relay is whether of not they were 'on' or 'off' and how often; and this occurs as an action potential firing frequency. There is no message in the sense that neurons might pass on complex messages, like an email for instance; or store memories of events and facts. No one neuron can do anything like that. It takes many neurons working together to achieve this.
There is no relay station in nerve impulse conduction.
axon
2,1,3,4
nerve impulse
A nerve impulse starts at the dendrite
a nerve impulse
they transport the nerve impulse through the synapses (:
no ventricular diastole is responsible for nerve impulse
A nerve impulse is approximately 1 millisecond.
How does a nerve impulse follow the all-or-nothing principle???
nerve my a$$ nerve
Yes, an action potential is needed for a nerve impulse to occur.
Yes, an action potential is needed for a nerve impulse to occur.
It is called a nerve impulse.