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| There’s a small gap between the axon of one neuron and the dendrites or cell body of another. This gap is part of the synapse, the junction or region between the axon of one neuron and the dendrites or cell body of another |
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| the axon is covered by a myelin sheath, an insulating layer of fatty material |
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| The myelin sheath is composed of glial cells (named for the Greek word for “glue”), which are support cells found in the nervous system. glial cells serving a variety of functions. Some glial cells digest parts of dead neurons, others provide physical and nutritional support for neurons, and others form myelin to help the axon carry information more efficiently |
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| receive information from the external world and convey this information to the brain via the spinal cord. They have specialized endings on their dendrites that receive signals for light, sound, touch, taste, and smell. |
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| carry signals from the spinal cord to the muscles to produce movement. These neurons often have long axons that can stretch to muscles at our extremities |
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| connect sensory neurons, motor neurons, or other interneurons. Some interneurons carry information from sensory neurons into the nervous system, others carry information from the nervous system to motor neurons, and still others perform a variety of information-processing functions within the nervous system |
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| When an electric current passes down the length of a myelinated axon, the charge seems to “jump” from node to node rather than traverse the entire axon, and it helps speed the flow of information down the axon. |
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| Neurons have a natural electric charge called the resting potential, the difference in electric charge between the inside and outside of a neuron’s cell membrane (Kandel, 2000). The resting potential arises from the difference in concentrations of ions inside and outside the neuron’s cell membrane |
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| The neuron maintains its resting potential most of the time. However, in the 1930s, biologists Alan Hodgkin and Andrew Huxley noticed that they could produce a signal by stimulating the axon with a brief electric shock, which resulted in the conduction of an electric impulse down the length of the axon ...an electric signal that is conducted along the length of a neuron’s axon to a synapse. |
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| Axons usually end in terminal buttons, knob-like structures that branch out from an axon. |
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| A terminal button is filled with tiny vesicles, or “bags,” that contain neurotransmitters, chemicals that transmit information across the synapse to a receiving neuron’s dendrites. |
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| parts of the cell membrane that receive neurotransmitters and either initiate or prevent a new electric signal |
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| a neurotransmitter involved in a number of functions, including voluntary motor control. Acetylcholine is found in neurons of the brain and in the synapses where axons connect to muscles and body organs, such as the heart. Acetylcholine contributes to the regulation of attention, learning, sleeping, dreaming, and memory |
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| a neurotransmitter that regulates motor behavior, motivation, pleasure, and emotional arousal. Because of its role in associating actions with rewards, dopamine plays a role in drug addiction (Baler & Volkow, 2006). High levels of dopamine have been linked to schizophrenia (Winterer & Weinberger, 2004), whereas low levels have been linked to Parkinson’s disease. |
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| the major excitatory neurotransmitter in the brain, meaning that it enhances the transmission of information between neurons. GABA (gamma-aminobutyric acid), in contrast, is the primary inhibitory neurotransmitter in the brain, meaning that it tends to stop the firing of neurons. Too much glutamate, or too little GABA, can cause neurons to become overactive, causing seizures. |
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| is involved in vigilance, or a heightened awareness of dangers in the environment |
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| involved in the regulation of sleep and wakefulness, eating, and aggressive behavior |
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| chemicals that act within the pain pathways and emotion centers of the brain (Keefe et al., 2001). Endorphins help dull the experience of pain and elevate moods. The “runner’s high” experienced by many athletes as they push their bodies to painful limits of endurance can be explained by the release of endorphins in the brain |
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