Alright buddy, in this post we will discuss about Nerve Impulse Travel
Impulses can be described as “electric currents” that propagate in nerve fibers. If a nerve fiber does not conduct an impulse, it is said to be at rest. Impulses can be transmitted through nerve cells and synapses.
Impulses can flow through nerve fibers because there is a difference in electrical potential between the outside and the inside of the nerve fiber [baca : Sistem Saraf Manusia]. When the nerve cell is at rest, the inside of the nerve fiber is negatively charged, about -60 mV, while the outside is positively charged. This state of electric charge is named resting potential, while the nerve fiber membrane is in a state polarization.
If an impulse travels through an axon [baca : Pengertian dan Jenis Sel Saraf (Neuron)], in a short time the inner charge of the impulse becomes positive, approximately +60 mV, and the outer charge becomes negative. The sudden change in resting potential along with an impulse is called work potential. At this time there is depolarization of the axon membrane. The process of depolarization propagates along the nerve fiber as the impulse propagates. As a result, the negative charge on the outside of the membrane propagates along the nerve fiber.
Mechanism of impulse passage through the nerve (different from the picture): (1) the neuron rests (2) the stimulus is given, giving rise to the impulse (3) the impulse travels as an electric current (4) the second stimulus is given (5) both impulses a certain distance away travel along the axon.
If the impulse has passed, then the nerve fibers cannot be passed by the impulse temporarily because the work potential becomes a resting potential. In order to function again, it will take approximately 1/1000 to 1/500 second for recovery.
The speed of the propagation of the impulse is different in each species. In certain mammals, impulse propagation can reach 100 meters per second, while in lower animals it may be only about 0.5 meters per second. Factors that affect the speed of this propagation are: (1) the myelin sheath, and (2) the diameter of the nerve fibers. In nerve fibers that have myelin, depolarization occurs only in the nodes of Ranvier, resulting in a jump in the work potential, so that the nerve impulse will propagate faster. The larger the diameter of the nerve fibers, the faster the propagation of nerve impulses [baca : Perbedaan Gerak Biasa dan Gerak Refleks].
A synapse is a meeting point between the neurite end (axon) of one neuron and the dendritic end of another neuron. Each end of the neurite swells to form a bulb called the synaptic bulb.synaptic knob). The synaptic tube contains mitochondria and synaptic vesicles. These synaptic bubbles contain chemicals neurotransmitterwhich plays an important role in transmitting nerve impulses to other nerves. There are various kinds neurotransmitter, among others acetylcholine found at synapses throughout the body noradrenaline found in the sympathetic nervous system, and dopamineas well as serotonin which is in the brain. [Baca juga : Pengertian, Bagian Telinga dan Fungsinya]
Between the end of the synaptic tubule and the membrane of the next nerve cell there is a synaptic cleft which is bounded by the presynaptic membrane (membrane of the synaptic tubule) and the postsynaptic membrane (dendritic membrane of the next nerve cell or effector membrane). When a nerve impulse reaches the synaptic clump, the synaptic vesicles approach the presynaptic membrane and release their contents, namely neurotransmitter, to the synaptic cleft. Nerve impulses carry Liem neurotransmitter this. Neurotransmitters across the synaptic cleft to the postsynaptic membrane. Chemicals neurotransmitter This will result in depolarization of the postsynaptic membrane and an action potential will occur. This means that the impulse has been given to the next nerve fiber. Thus the nerve impulses cross the synaptic cleft by means of the transfer of chemicals, and then proceed to the next nerve cell by means of propagation of work potentials. [baca : Sistem Saraf Pusat (Otak dan Sumsum Tulang Belakang)]
When the neurotransmitter has done its job, it will be broken down by enzymes produced by the postsynaptic membrane. For example, if the neurotransmitter is acetylcholine, the enzyme that will break it down is an enzyme acetylcholinesterase [baca : Sistem Saraf Tepi (Saraf Kranial dan SarafOtonom)].
- Syamsuri, Istamar. Biology 2A for high school. Jakarta : Erlangga.
This is the post this time about Nerve Impulse Travel, hopefully useful for all friends. Thank you very much J