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Nervous System
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Without it, you couldn't exist! Made up of your brain, your spinal cord, and a network of nerves. Your brain uses information it receives from your nerves to coordinate all of your actions and reactions. |
Neuron
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A specialized, impulse-conducting cell. CENTER OF THE NERVOUS SYSTEM Consists of the cell body, axon, and dendrites. |
Cell Body
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Generates energy needed to carry out the work. |
Dendrites
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Root like structures, attached to the cell body of neuron, that receive impulses form other neurons. |
Axon
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A long, thin part of a neuron that transmits impulses to other neurons from terminal buttons. |
What is a neuron's job?
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Carry messages in ONE DIRECTION from dendrites/cell body, through axon, to axon terminals. Then transmits messages from terminal buttons to other neurons, muscles, or glands |
Glial Cells
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Remove dead neurons & waste from the nervous system, nourish neurons, and direct their growth. |
Myelin
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A fatty substance that decreases leakage of electrical current being carried along the axon, allowing messages to conduct regularly. |
Afferent Neurons
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(Sensory Neurons) Receive & transmit messages from sensory receptors to the spinal cord and brain. Ex: The feeling you get in your foot after someone steps on it. |
Efferent Neurons
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(Motor Neurons)
Transmit messages from the brain or spinal cord to muscles and glands. Ex: Hopping around after someone steps on your foot. |
Luigi Galvani
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Discovered that neural impulses are electrochemical. *Connected lightning rods to dissected frogs. When lightning struct their muscles contracted. |
Neural Impulses
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Electrochemical messages that travel within neurons at somewhere between 2 and 225 mph. (neurons & body fluid contain ions in resting state) Chemical changes happen within neurons which cause them to be transmitted. |
Polarize/Resting Potential
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An unequal distribution of ions (atoms with a positive or negative charge) on the two sides of the nerve cell membrane. Expressed as -70 mV, and the minus means that the inside is negative relative to (or compared to) the outside. It occurs when a membrane is not being stimulated or conducting impulses. |
Peripheral part of the nervous system
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Everything except the brain & spinal cord |
Depolarize
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To reduce the resting potential of a cell membrane from about 70 millivolts to -----> 0. positive charge
Permeability of the cell membrane changes again, allowing no more sodium ions to enter. |