Nervous System GROUP 1 By Ally, Maddie, Emma and Mimi (7)

Structures of a Motor Neuron (5)

●Dendrites (Input Zone): thin extensions that receive information ●Axon (Conducting Zone): conducting area that passes the message to their ends, their branched endings send messages to other cells ●Myelin Sheath: surrounds the axon and help increase rate of action potential as well as efficiency. ●Trigger zone: area between axon and cell body that compiles information ●Motor End Plates (Output Zone): branched endings of the axon that send the messages to other cells ●Overall Function: to send electrical signals to muscles, telling them to contract or relax (2) Functions of Motor Neuron

● Output zones of neurons send messages to other cells ● Neurons regulate electric charge of their plasma membrane ● Ions can only go through proteins (both pumps and channel) (3) Neuron Controls on Membrane Transport

Two main ions: Potassium and Sodium (both have a +1 charge) Others: Calcium (+2 charge) and chlorine (-1 charge) (1) ●Keeping concentrations of these ions is vital to the neuron ○ Regulated by sodium potassium pumps (2) Important Ions

●The lipid bilayer of the cell prevents the ions K + and Na + from passing through the cell membrane freely ●Because of this, for the ions to enter the neuron they need to use transport proteins! ○ Channel Proteins - passive transport (no energy used) Openings in the membrane where ions can pass through without being barred by the membrane (2) ○ Sodium Potassium Pumps ■ Uses ATP energy to transport sodium and potassium in and out of the membrane ■ Compensates for ions leaking out of the neuron (via channel proteins) and restore gradient after action potential ■ Voltage sensitive gates that open and shut in controlled ways between action potential Channel Proteins and Transport Proteins

● Inside of the cell is more negative than the outside (2) - Higher concentration of K + inside the cell and higher concentration of Na + outside the cell ● Potassium ions can pass freely through the membrane but other ions have more difficulty (1) ● Resting potential: energy inherent based on the constant voltage difference inside and outside the neuron (1) ○ Average resting potential = -70 millivolts (1) ○ High concentration of sodium ions inside the neuron and high concentration of potassium ions outside the neuron (1) Neuron at Rest (NOT Signaling)

●Trigger: stimulus causes neuron to rapidly send information (through electrical activity) to surrounding cells ●Stimulus has to pass a threshold level in order to reach action potential ●Process: Sodium ions (+1) rush into the neuron because it is negatively charged (Sodium channels open quickly, but potassium channels take longer) (1) ●The Myelin Sheath isolates part of the neuron so these electrical charges jump on top of exposed nodes on the neuron. This increases the travel time of action potential (enhances action potential propagation) Action Potential (Spike)

ACTION POTENTIAL (continued) ●Potassium channels open first, allowing positive potassium ions move into the cell rapidly (1) ●Because of this quick process, the inside of the neuron is now positive while the outside of the membrane is negative (reversed) ●The sodium potassium pumps then react and bring sodium back into the cell and the potassium back out into the surrounding area ●At this point, resting potential has temporarily been restored (2)

Would anyone like to volunteer? passing-through/ (4) Interactive Part

1.Chudler, Eric H., PhD. "Action Potential." Neuroscience for Kids- Action Potential. Eric H. Chudler, n.d. Web. 14 Nov Starr, Cecie, Ralph Taggart, and Lisa Starr. "34 Information Flow and the Neuron." Biology: The Unity and Diversity of Life. South Melbourne: Thomson Brooks/Cole, Print. 3.Gregory, Michael J., PhD. "Neurons." Neurons. Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License., n.d. Web. 14 Nov < files/bio%20102/bio%20102%20lectures/Nervous%20System/neurons.htm>. 4."Cell Membrane: Just Passing Through." PBS Learning Media. ©2002 WGBH Educational Foundation, 1 Jan Web. 14 Nov : Images 5.pic007.gif. N.p., n.d. Web. 14 Nov < content/file/969144ed-0d3b-fa04-2e88-8b23de2a630c/1/human_bio_science_3b.zip/ content/002_nervous_control/images/pic007.gif>. 6.Class Connection. N.p., n.d. Web. 15 Nov < neuron gif>. 7. Central Chromatolysis - Intermed Mag - Cropped.jpg Wikimedia. Web. 16 Nov Bibliography

(Through 7:22) passing-through/ (4) Extra Resources