![]() ![]() If depolarization exceeds a certain threshold, an impulse (i.e., action potential) will travel along the neuron. A decrease in the voltage difference is called depolarization. ![]() The resulting redistribution of electric charge may alter the voltage difference across the membrane. The channels “open” or “close” in response to neurotransmitters or to changes in the cell’s membrane potential. Ions enter and exit the cell through specific protein channels in the cell’s membrane. This membrane potential is created by the uneven distribution of electrically charged particles, or ions, the most important of which are sodium (Na +), potassium (K +), chloride (Cl −), and calcium (Ca 2+). The mechanism underlying signal transmission within neurons is based on voltage differences (i.e., potentials) that exist between the inside and the outside of the cell. Second, for communication between cells, the electrical signals generally are converted into chemical signals conveyed by small messenger molecules called neurotransmitters. First, within cells, electrical signals are conveyed along the cell membrane. Two mechanisms have evolved to transmit nerve signals. Also, because individual neurons can be up to 3 feet long, a rapid-relay mechanism within the neurons themselves is required to transmit each signal from the site where it is received to the site where it is passed on to a neighboring cell. Dozens of neurons can be involved in such a circuit, necessitating a sophisticated communication system to rapidly convey signals between cells. For example, if you step barefooted on a sharp object, the sensory information is relayed from your foot all the way to the brain from there, nerve signals travel back to the leg muscles and cause them to contract, drawing back the foot. Nerve signals often travel over long distances in the body. The neuron has three main components: (1) the dendrites, thin fibers that extend from the cell in branched tendrils to receive information from other neurons (2) the cell body, which carries out most of the neuron’s basic cellular functioning and (3) the axon, a long, thin fiber that carries nerve impulses to other neurons. Within the neuron itself, information is passed along through the movement of an electrical charge (i.e., impulse). It conveys information both electrically and chemically. Neurotransmitter-containing vesicles do not exist in dendrites.Ĭonducts nerve impulses away from the cell body.Ĭonducts nerve impulses towards the cell body.The nerve cell, or neuron, is the key player in the activity of the nervous system. Nissl’s Granules are present in dendrite.Īxon synaptic knobs contain vesicles containing neurotransmitters. There are no synaptic knobs at the ends of the branches of the dendrites. The terminals of the terminal branches of the axon are enlarged to form synaptic knobs. The diameter of dendrites decreases over time because of their tapering ends. Īxons are quite lengthy (several meters) 0.25- over10mmĭendrites are very short strands of tissue (generally below 1.5 mm). The term “axon” refers to the long, thread-like component of a nerve cell that transports nerve impulses away from the cell body.ĭendrites are the small branched extensions of nerve cells that transport nerve impulses from synapses to the cell body. NERVE IMPULSE CONDUCTION Difference between Axon and Dendrite Parameter The axon is located at the distal end of a neuron and relay output message.Ī myelin sheath, a fatty tissue commonly seen on axons which acts as an insulator and significantly increases the conductance of the electrical impulse or message along the axon. An axon can be thinner than the width of the human hair. The length of an axon can range from 1 millimeter in the brain to over 1 meter in the spinal cord. It is possible for certain big axons to transfer impulses up to 90 meters (300 feet) per second. For example, from the spinal cord down to toe.Vertebrate axons are protected by a myelin coating, which speeds up impulse transmission. ![]() Axons are extremely small neural fibers that transfer nerve impulses from one neuron to another neuron. A neuron is in charge of processing and relaying the electrical signals involved in receiving sensory information, providing motor instructions to your muscles, and controlling movement. Each neuron contains one axon that connects it to other neurons, muscle cells, or glandular cells. Some axons may be quite long, reaching. ![]()
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