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What is a neuron?. The Neuron. A neuron is a nerve cell like any other cell in the body Neurons are similar to other cells in the body in some ways However, neurons differ from other cells in the body in some ways. 3 major classes of neurons. Sensory (afferent) Motor (Efferent)
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The Neuron A neuron is a nerve cell like any other cell in the body Neurons are similar to other cells in the body in some ways However, neurons differ from other cells in the body in some ways
3 major classes of neurons Sensory (afferent) Motor (Efferent) Interneurons Glia cells development housekeeping insulation protection
The process of neural communication Within cells - action potential Between cells - synaptic transmission Components: dendrites, soma (cell body), axon, and terminal buttons of axon
The Neuron at Rest Resting potential - Cell is Polarized neuron membrane separates charged ions, producing a voltage potential sodium (NA+), potassium (K+), chloride (Cl-), and protein molecules (A-) selectively permeable (semi-permeable) sodium-potassium pump maintains ionic imbalance inside of neuron is negative relative to outside (about -70mV)
Reception of Input Graded potentials: Excitatory potentials -depolarizing current Inhibitory potentials - hyperpolarizing current determines which ion channels open Excitatory input causes the ion channels to allow sodium ions into neuron allows neuron to fire Inhibitory input causes ion channels to keep neuron negatively charged prevents neuron from firing
Synaptic Transmission Presynaptic and postsynaptic neurons Transmission involves movement of neurotransmitters across synaptic cleft about 200 angstroms (one ten-millionth of a millimeter) in width b/t neurons Once AP reaches terminal button, vesicles spill contents into gap Traverse cleft, attach to receptor molecules Either increase (E) or decrease (I) neural firing
Neurotransmitters Acetylcholine, ACH learning and memory motor neurons and muscles major excitatory neurotransmitter Gamma-Amino Butyric Acid (GABA) major inhibitory neurotransmitter anxiety
Neurotransmitters Catecholamines: Norepinephrine undersupply - depression Dopamine oversupply - schizophrenia undersupply - Parkinson’s Serotonin mood, sleep, and eating Endorphins natural pain killers