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PSY 212
Chapter 2: Communication within the Nervous System
| Term | Definition |
|---|---|
| neurons | convey sensory information into the brain; carry out the operations involved in thought, feeling, and action; and transmit commands out to the body to control muscles and organs |
| types of neurons | bipolar neuron, unipolar neuron, multipolar neuron, pyramidal neuron |
| bipolar neuron (interneuron) | relays a signal from one neuron to another |
| unipolar neuron | common in sensory systems, detects stimuli, relays message to CNS (central nervous system) |
| multipolar neuron | commonly motor neurons responsible for executing movement |
| pyramidal neuron | CNS only contain “dendritic” spines, found in areas involved in learning, memory and synaptic plasticity |
| soma | cell body, contains nucleus and other cellular machinery |
| motor neuron | carries commands to the muscles and organs |
| sensory neuron | carry information from the body and the outside world into the brain and spinal cord |
| interneurons | connect one neuron to another in the same part of the brain or spinal cord |
| dendrites | branches that serve as the primary input to the neuron (primary receiver) |
| axon | cable-like structure through which action potentials (impulses) are conducted |
| axon terminals | branches at the end of the axon culminate in swellings |
| terminal buttons | portion of the neuron containing neurotransmitter release machinery necessary for communication |
| synapse | space in which two neurons communicate via chemical/electrical signals |
| neurotransmitters | neuron releases to communicate with a muscle, an organ, or the next neuron in a chain |
| polarization | there is a difference in electrical charge between the inside and outside of the neuron |
| voltage | a difference in electrical charge between two points, such as the poles of a battery or between the inside and outside of a neuron |
| resting potential | difference in charge between the inside and outside of the membrane of a neuron at rest |
| ions | atoms that have lost or gained one or more electrons |
| force of diffusion | ions tend to move through the membrane to the side where they are less concentrated |
| electrostatic pressure | ions are repelled from the side that is similarly charged and attracted to the side that is oppositely charged |
| sodium-potassium pump | consists of large protein molecules that move sodium ions through the cell membrane to the outside and potassium ions back inside the cell |
| action potential | abrupt depolarization of the membrane that allows the neuron to communicate over long distances |
| graded potential | it varies in magnitude with the strength of the stimulus that produced it |
| all-or-none law | it occurs at full strength or it does not occur at all |
| nondecremental | it travels down the axon without any decrease in size, propagated anew and at full strength at each successive point along the way |
| absolute refractory period | during the action potential and initial recovery, the sodium ion channels are open and unresponsive to further stimulation, no matter how intense |
| relative refractory period | another action potential can be generated but only by a stronger-than-threshold stimulus |
| rate law | the axon encodes stimulus intensity not in the size of its action potential but in its firing rate |
| glial cells | nonneural cells that provide a number of supporting functions to neurons. Means “glue” |
| types of glia | microglia, astrocytes, oligodendrocytes, schwann cells |
| microglia | provides immune response, cell maintenance, spatial buffering and may even release neurotransmitters |
| astrocytes | star-shaped cells that wraps around neurons and supply them with nutrients (usually lactates for ATP synthesis). Also immune function and phagocytosis |
| oligodendrocytes | provides myelin in CNS (central nervous system) cells |
| schwann cells | provides myelin in PNS (peripheral nervous system), and also helps neurons repair themselves |
| blood-brain barrier (BBB) | selectively permeable barrier occurring between CNS blood vessels and neurons; large proteins actively transported through the membrane or do not; other molecules (glucose, waste, etc.) are moved in and out via active transport (ATP-dependent transport) |
| excitation | activation of a neuron leading to its stimulation |
| inhibition | deactivation of a neuron leading to its “silence” |
| saltatory conduction | action potential thus appear to jump from node to node in a form of transmission |
| synaptic cleft | the neurons are not in direct physical contact at the synapse, but are separated by a small gap |
| presynaptic neuron | output neuron; neuron that is transmitting to another neuron |
| postsynaptic neuron | input neuron; the receiving neuron |
| ionotropic receptors | form the ion channel and open quickly to produce the immediate reactions required for muscle activity and sensory processing |
| metabotropic receptors | open channels indirectly through a second messenger; they act slowly and produce longer-lasting effects |
| partial depolarization | its excitatory and facilities the occurrence of an action potential; increased polarization |
| hyperpolarization | inhibitory, and makes an action potential less likely to occur |
| excitatory postsynaptic potential (EPSP) | partial depolarization of the dendrites and the cell body |
| inhibitory postsynaptic potential (IPSP) | hyperpolarization of the dendrites and the cell body |
| reuptake | transmitters are taken back into the terminals by membrane proteins |
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