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Nervous System: Group 1. By Brian, Charlie, Nick, and Taylor. Motor Neuron: a neuron that is located in the central nervous system that projects its axons to directly or indirectly control muscles. Background Info.
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Nervous System: Group 1 By Brian, Charlie, Nick, and Taylor
Motor Neuron: a neuron that is located in the central nervous system that projects its axons to directly or indirectly control muscles.
Background Info. Neurons send messages electrochemically, meaning that chemicals cause an electric signal. Membrane potential - a difference in electrical charge between the inside and outside of the plasma membrane (3) • This changing in charge is the transmitting of a neural signal
Video on resting and action potential https://www.youtube.com/watch?v=oRYpt8_OJms
Ionic Diffusion Potassium (K+) and Sodium (Na+) are the two major ions that pass through the membrane, both affecting the electrochemical gradient of the cell. Protein pumps actively transport 3 sodium ions out of the cell for every 2 potassium ions that are actively transported into the cell, maintaining the relatively negative charge of the cell
Functions of the Structures Nucleus - contains DNA, provides instructions for the cell (1) Cell Body (Soma) - produces proteins, contains organelles, provides energy in the form of ATP Dendrites - Passes information that is gathered from other neurons Axon - Primary transmission lines, sends electrical impulses away from the neuron’s cell body Myelin Sheath - insulates the Axon, helps the electrical current run down the axon (like putting tape around a hose with holes in it helps the water flow through the hose)(1) Muscle Fibre - controlled by the neuron (2) Motor End Plate - transmits neural impulses to a muscle Node - The gap between the myelin sheaths
Resting Potential Resting Potential describes the state of a neuron at rest When a neuron is not sending signals, it is usually between -60 and -80 millivolts (mV) (negative sign means the inside of the cell is negative compared to the outside) -Concentration of K+ is higher inside the cell (3) -Concentration of Na+ is higher outside the cell (3) These concentration gradients are maintained by protein pumps (specifically sodium-potassium pumps)
Action Potential • As a stimulant changes the distribution of charge across the membrane sufficiently, the gated sodium channels open (1) • This allows for movement of sodium across the membrane to occur • As movement occurs the charge on the inside of the cell becomes more positive and the charge on the outside of the cell becomes more negative • This change in charge causes for the gated potassium channels to open • as the Potassium ions move out of the cell the original charge system is reestablished, closing the gated potassium channels • This process continues, moving the electric signal across the cells and eventually to another cell (neuron, muscle fiber, etc.) • Remember that the changing of electric charges is the transmission of a neural signal • This whole process of moving the active potential from neuron to neuron is enhanced by the myelin sheath, which acts as insulation, increases the speed of transmission across the axon (3)
Bibliography 1. Chudler, Eric. "Saltatory Conduction." Neuroscience for kids. N.p.. Web. 3 Nov 2013. <http://faculty.washington.edu/chudler/salt.html>. 2. Helena Cardoso, Silvia. "Parts of the Nerve Cell and Their Functions." Brain And Mind. N.p.. Web. 3 Nov 2013. <http://www.cerebromente.org.br/n07/fundamentos/neuron/parts_i.htm>. 3. Starr, Cecie . Biology The University and Diversity of Life . Brooks/Cole, print.
