Term
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Definition
| They are nerve cells that specialize in electrical signaling for intercellular communication over long distances |
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Term
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Definition
| Not capable of electrical signaling, but are essential in the developing in adult brain, contributors to repair the damaged nervous system, and promoting regrowth of damaged neurons or preventing such regeneration. |
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Term
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Definition
| Dendrites are the primary target for synaptic input from other neurons and are distinguished by their high content of ribosomes, as well as by specific cytoskeletal proteins. |
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Term
| The number of inputs that a neuron receives depends on____________________________. |
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Definition
| the complexity of its dendritic arbor. The more dendrites, the more input that can be innervated. |
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Term
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Definition
| The number of inputs to a single neuron |
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Term
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Definition
| the number of targets innervated by any one neuron |
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Term
| What is the presynaptic terminal? |
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Definition
| a specialized area within the axon of the presynaptic cell that contains neurotransmitters enclosed in small membrane-bound spheres called synaptic vesicles |
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Term
| What is the postsynaptic specialization? |
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Definition
| found at the end of dendrites and immediately across from the presynaptic terminal, it possesses receptors on its surface that recognize and accept the molecules secreted by the presynaptic terminal |
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Term
| What is the synaptic cleft? |
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Definition
| it is the site of extracellular proteins that influence the diffusion, binding, and degredation of molecules secreted by the presynaptic terminal |
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Term
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Definition
| The axon is where information conveyed by the synapses on the neuronal dendrites is integrated and 'read out'. The axon is the portion of the nerve cell specialized for relaying electrical signals. |
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Term
| Axons have a special array of microtubules for: |
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Definition
- stability and integrity
- specialized transport of vesicles to and from synaptic endings
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Term
| What are the 3 morphological neurons types? |
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Definition
- unipolar cell
- bipolar cell - found in the retina, cell body is centered above axon.
- pseudo-unipolar cell - sensory neurons, cell body off to the side
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Term
| What are the 3 types of Multipolar Cells? |
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Definition
- spinal motor neuron
- Hippocampal pyramidal neuron
- Purkinje Neuron of cerebellum
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Term
| What are Mulipolar Cells? |
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Definition
| cells that have multiple dendrites and an axon that has multiple branches |
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Term
| What are the 4 main regions that neurons have? |
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Definition
- input - where signal is received
- integrative - where signal is read and integrated
- conductile - action potential
- output - secrete the signal
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Term
| What is the axon hillock? |
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Definition
| It is the region where synaptic inputs to the dendrites are integrated and summed. This is the site of initiation of action potentials |
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Term
| What is action potential? |
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Definition
| A self-regenerating was of electrical activity that carries signals over long distances. It propogates from its point of initiation at the cell body to the terminus of the axon. |
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Term
| A synaptic contact is usually made between a _____ and a _______, but sometimes between a ______ and a ________. |
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Definition
| axon, dendrite, axon, soma |
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Term
| A _______ ________ is a specialized secretory apparatus that contains many synaptic vesicles loaded with neurotransmitters |
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Definition
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Term
| Neurotransmitters bind to what after they're secreted? |
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Definition
| neurotransmitter receptors |
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Term
| The Presynaptic Terminal has 3 other names. What are they? |
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Definition
| terminal boutons, axon terminal, synaptic ending |
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Term
| Name the different types of synapses and describe them. |
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Definition
- axo-denritic - an axon to a dendrite
- axo-axonic - an axon to an axon
- axo-somatic- an axon to a cell body
- en-passant synapse - an axon that keeps on going after contact with the dendrite
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Term
| Where are the postsynaptic apparati located? |
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Definition
| on the spine heads of the dendritic spine |
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Term
| The presynaptic terminals contact the dendrite at what specific location? |
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Definition
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Term
| What are the four types of functional neuron types? |
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Definition
- sensory
- motor
- projection
- interneuron
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Term
| What is a sensory neuron? |
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Definition
| receive information from the external world and transmit that info to the central nervous system. Touch, taste, smell, hear... |
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Term
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Definition
| start at spinal cord and end directly on muscles and transmit the output of the central nervous system. Responsible for the regulation of muscle activity. |
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Term
| What is an afferent neuron? |
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Definition
| nerve cells that carry information from the periphery toward the brain or spinal cord. |
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Term
| What is an efferent neuron |
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Definition
| nerve cells that carry information away from the brain or spinal cord |
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Term
| What is a projection neuron? |
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Definition
| nerve cells that project their axons out of the nucleus or area. Usually have very long axons |
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Term
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Definition
| nerve cells with all their processes, including the axon, within a nucleus or localized area. Don't leave the area where their cell body sits. |
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Term
| What are neural circuits? |
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Definition
| ensembles that neurons are organized into. |
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Term
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Definition
that area in and around the cell bodies where most
synaptic connectivity occurs. Dense tangle of axon terminals, dendrites, and glial processes |
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Term
| What's located in the gray matter of the central nervous system? |
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Definition
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Term
| What's located in the white matter of the central nervous system? |
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Definition
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Term
| What's located in the gray matter of the peripheral nervous system? |
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Definition
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Term
| What's located in the white matter of the peripheral nervous system? |
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Definition
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Term
| What comprises of the central nervous system (CNS)? |
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Definition
| the brain (cerebral hemispheres, diencephelon, cerebellum, and brainstem), and spinal cord |
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Term
| What comprises of the peripheral nervous system? |
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Definition
| sensory neurons that link sensory receptors on the body surface or deeper within it with relevant processing circuits within the CNS. |
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Term
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Definition
| more numerous than neurons, they are the support cells associated with them |
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Term
| Name the types of glial cells found in the CNS? |
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Definition
Macroglia
- astrocytes
- oligodendrocytes
- ependymal cells
Microglia - scavangers, eat up all the debris |
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Term
| What types of glial cells are found in the PNS? |
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Definition
- Schwann cells
- Satellite cells
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Term
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Definition
a class of glial cell found in the CNS. Have no axons and form blood/brain barrier.
•Induce tight junction formation by
endothelial cells
•guide neuroblast migration and axon growth
•Take up neurotransmitters within synaptic region
•take up excess K+ released during high neuronal activity
•provide metabolic support to neurons
•in certain areas of the brain, astrocytes can act as stem cell/
progenitors in the adult and embryonic brain. |
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Term
| Name the two classes of astrocytes |
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Definition
- Fibrous astrocytes
- Protoplasmic astrocytes
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Term
| What are fibrous astrocytes and where are they found? |
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Definition
Found in white matter, they care complex cells with 50 to 60 long branching processes that radiate from the cell body and terminate in end feet at:
- freely among axons
- blood vessels
- pial surface
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Term
| What are protoplasmic astrocytes and where are they found? |
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Definition
Found in gray matter, they have profuse short stubby processes that contact:
- pial surfaces
- blood vessels
- surround neurons
- ensheath virtually every synapse
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Term
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Definition
| Guided by specialized astrocytes called radial glia, a neuroblast is a dividing cell - the progeny of which will develop into neurons |
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Term
| Astrocytes regulate _____ ______ in the _______ _______. |
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Definition
| ionic concentration, synaptic cleft |
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Term
| Astrocytes rapidly clear excess K+ when it is released by neurons. If this function is interfered with, abnormally high K+ can cause __________ due to excess neuron activity |
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Definition
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Term
| How do astrocytes regulate the concentration of neurotransmitters? |
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Definition
| they envelop synapses in such a manner that would enable them to intercept neurotransmitter molecules that overflow from the synaptic cleft. They are also equipped with transport systems and enzymes that are necessary to degrade most known transmitters |
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Term
| Astrocytes provide metabolic support and nourishment to neurons by: |
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Definition
- receiving glucose from capillaries
- breaking glucose down into lactate
- release the lactate into the extracellular fluid surrounding the neurons. Neurons pick up lactate and transport it to their mitochondria to use for energy.
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Term
| What do oligodendrites do? |
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Definition
| Responsible for creating the myelin sheath |
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Term
| What is the myelin sheath? |
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Definition
| Formed by oligodendrites or Schwann cells, it is the multilayer lipid sheath around some axons that help increase action potential |
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Term
| What is the Node of Ranvier |
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Definition
| periodic gaps in the myelin sheath where sodium potassium can diffuse |
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Term
| During the formation of the myelin sheath, ___________ is withdrawn and the sheath becomes __________. (Called __________). |
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Definition
| cytoplasm, compact, compaction |
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Term
| The composition of the myelin sheath includes ______ and _______. |
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Definition
- lipids (cholesterol, glycosphingolipids, phospholipids)
- proteins (myelin basic protein (MBP), and proteolipid protein (PLP))
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Term
| What is the Myelin Basic Protein |
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Definition
| A major component of mammalian CNS, it is a structural protein that helps glue the insides together. |
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Term
| Myelin Basic Protein is located on the surface of the _____________ __________ via electrostatic interactions with negatively charged lipids (compact internodal myelin). |
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Definition
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Term
| MBP is functionally involved in ________ formation and compaction |
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Definition
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Term
| What is the Proteolipid Protein? |
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Definition
| The most abundant myelin protein in mammalian CNS, it is a hydrophobic protein covalently bonded to long chain fatty acids that helps in stabilizying myelin architecture. |
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Term
| Deletion of a major portion of the MBP gene results in ________. |
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Definition
| shiverer mice (Parkinson's in humans?) |
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Term
| Mutations of the PLP in humans causes ____________________________. |
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Definition
| Pelizaeus-Merzbacher Disease |
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Term
| The PLP has a functional role in supporting ________ integrity, _________ adhesion, and ________ compaction |
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Definition
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Term
| Ependymal cells form an ________ layer called ___________. |
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Definition
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Term
| Ependymal cells line the central canal of the ______ _____ and the ventricles of the ________. |
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Definition
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Term
| Ependymal cells have ______ that help beat and circulate _______. |
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Definition
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Term
| Ependymal cells have _______ that absorb CSF, but also produce CSF |
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Definition
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Term
| What is the choroid plexus? |
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Definition
| a population of specialized ependymal cells and capillaries |
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Term
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Definition
| They practice phagocytosis of dead or diseased neurons and are only found in the CNS |
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Term
| Name the two types of Schwann Cells |
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Definition
- Myelinating Schwann cells
- Non-myelinating Schwann cells
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Term
| What are myelinating schwann cells? |
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Definition
| Similar to oligodendrocytes, they generate a myelin sheath, but only have one axon, and are located in the PNS. (sensory and motor axons) |
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Term
| What are non-myelinating schwann cells? |
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Definition
| Located in the PNS, they surround and nourish multiple axons such as: some sensory axons, sypathetic axons, and parasympathetic axons |
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Term
| What are Satellite cells? |
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Definition
| Associated with the cell body of sensory and other types of neurons in the PNS, they line the exterior surface of the cell body, supply nutrients, and have control over the microenvironment. |
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