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Definition
| nervous system cells that receive information and transmit it to other cells. |
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| Membrane(or plasma membrane) |
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| Surface of a cell which separates the inside of the cell from the outside environment. |
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| Structure in an animal cell that contains the chromosomes. |
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| Mitochondrion(pl.:mitochondria) |
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| The structure that performs metabolic activities, providing the energy that the cell requires for all other activities. Mitochondria require fuel and oxygen to function. |
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| The sites at which the cell synthesizes new protein molecules. |
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| A network of thin tubes that transport newly synthesized proteins to other locations. |
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| cell body in spinal cord. Receives excitation from other neurons through its dendrites and conducts impulses along its axon to a muscle |
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| specialized at one end to be sensitive to a particular type of sensation(light sound or touch). Cell body located on a little stalk off the main trunk |
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| branching fibers that get narrower near their ends.(comes from greek word meaning "tree") Dendrites surface lined with specialized synaptic receptors at which he dendrites receives information from other neurons |
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Definition
| The short outgrowths that increase the surface area available for synapses. |
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| Cell Body / Soma (pl.:Somata) |
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Definition
| Contains nucleus, ribosomes, mitochondria, and other structures found in most cells. |
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Definition
| An insulating material covering vertebrate axons |
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| Interruptions in the myelin sheath |
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| Swollen tips at end of axon, also known as "end bulb" or "bouton". The point from which the axon releases chemicals that cross through the junction between one neuron and the next |
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Definition
| Brings information into a structure (A=admission) |
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Definition
| carries information away from structure (E=Exit) |
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| Interneuron / intrinsic neuron |
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Definition
| If a cell's dendrites and axon are entirely contained within a single structure |
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Definition
| the other major components of the nervous system, do not transmit information over long distances like neurons do, although they do exchange chemicals with adjacent neurons. (derived from greek word meaning "glue") |
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| star shaped glia that wrap around the presynaptic terminals of a group of functionally related axons. By taking up chemicals released by axons and then releasing them back to the axons, an astrocyte helps synchronize the activity of the axons, enabling them to send messages in waves. |
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Definition
| very small cell, also remove waste material as well as viruses, fungi, and other microorganisms |
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| in brain and spinal cord specialized types of glia that build the myelin sheaths that surrond and insulate certain vertebrate axons |
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Definition
| in periphery specialized types of glia that build the myelin sheaths that surrond and insulate certain vertebrate axons |
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| guide the migration of neurons and their axons and dendrites during embryonic development. When embryological development finishes, most radial glia differentiate into neurons |
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| most chemicals cannot cross form blood to brain. To minimize the risk of irreparable brain damage, the body builds a wall along the sides of the brain's blood vessels. This wall keeps out most viruses, bacteria, and harmful chemicals. Oxygen and Carbon can cross the barrier. glucose and certain amino acids cross the barrier with help from active transports |
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Definition
| a protein-mediated process that expends energy to pump chemicals from the blood into the brain. Chemicals include glucose, amino acid, purines, choline, a few vitamins, iron, and certain hormones. |
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Definition
| a simple sugar that vertebrate neurons depend on |
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| a chemical that is necessary for the use of glucose. Prolonged thiamine deficiency can lead to death of neurons and a condition called "Korsakoff's syndrome", marked by severe memory impairments. |
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Definition
| Information sender of the neuron, conveying an impulse toward other neurons or an organ or muscle. Thin fiber of constant diameter, in most cases longer than dendrites. ( comes from greek word meaning "axis") |
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Definition
| A difference in electrical charge between the inside and outside of the cell |
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Definition
| During absence of outside disturbance the membrane maintains a difference in electrical charge between two locations. |
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Definition
| The neuron inside the membrane has a slightly negative electrical potential with respect to the outside, primarily because of negatively charged proteins inside the cell. |
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Definition
| Some chemicals can pass through it more freely than others can. |
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| A protein complex, repeatedly transports three sodium ions out of the cell while drawing two potassium ions into it. |
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Definition
| Sodium is positively charged and the inside of the cell is negatively charge. Opposite electrical charges attract, so the electrical gradient tends to pull sodium into the cell. |
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| The difference in distribution of ions across the membrane. |
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Definition
| Increased polarization. (i.e. from negatively charged to very negatively charged) |
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| Reduce polarization toward zero |
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Definition
| Stimulation beyond this point produces a massive depolarization of the membrane. When the potential reaches the threshold, the membrane opens its sodium channels. |
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Definition
| A rapid depolarization and slight reversal of the usual polarization. |
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Definition
| The membrane proteins that control sodium entry |
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Definition
| attach to the sodium channels of the membrane preventing sodium ions from entering |
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Definition
| For a given neuron all action potentials are approximately equal in amplitude and velocity under normal circumstances. The amplitude and velocity of an action potential are independent of the intensity of the stimulus that initiated it. |
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Definition
| Happens immediately after an action potential during which it resists the production of further action potentials. |
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Term
| Absolute refractory period |
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Definition
| First part of refractory period when the membrane cannot produce an action potential regardless of the stimulation |
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| Relative refractory period |
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Definition
| A stronger than usual stimulation is necessary to initiate an action potential. |
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Definition
| A swelling where the axon exits the soma. In a motor neuron this is where action potential begins. |
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Term
| Propagation of the action potential |
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Definition
| Describes the transmission of an action potential down an axon. |
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Definition
| An insulating material composed of fats and proteins. |
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Definition
| Axons covered with a myelin sheath |
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Definition
| The jumping of action potentials from node to node. Provides rapid conduction of impulses and conserves energy.(from Latin word saltare, meaning to "jump") |
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Definition
| Membrane potentials that vary in magnitude without following the all-or-none law. |
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| Neurons without axons exchange information only with their closest neighbors. |
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