Term
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Definition
| Master controlling and communicating system of the body. |
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Term
| Functions of the Nervous System |
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Definition
Sensory input - monitoring stimuli
Integration - interpretation of sensory input
Motor output - response to stimuli |
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Term
| Organization of the Nervous System |
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Definition
CNS - Central Nervous System
PNS - Perepiheral nervous system |
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Term
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Definition
| Brain and spinal cord, integration and command center |
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Term
| Peripheral nervous system |
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Definition
| Paired spinal and cranial nerves. Carries messages to and from the spinal cord and brain |
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Term
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Definition
| Sensory (afferent) and Motor (efferent) |
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Term
| Sensory (afferent) division of the PNS |
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Definition
| Sensory afferent fibers, carry impulses from skin, skeletal muscles, and joints to the brain. Visceral afferent fibers - transmit impulses from visceral organs to the brain |
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Term
| Motor (efferent) division |
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Definition
| Transmits impulses from the CNS to effector organs |
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Term
| Motor Division: Two main parts |
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Definition
| Somatic nervous system, Autonomic nervous system |
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Term
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Definition
| Conscious control of skeletal muscles |
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Term
| Autonomic nervous system (ANS) |
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Definition
| Regulates smooth muscle, cardiac muscle, and glands. |
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Term
| Divisions of the Autonomic Nervous System (ANS) |
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Definition
| Sympathetic and parasympathetic |
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Term
| Histology of nerve tissue |
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Definition
| Two principal cell types: Neurons, supporting cells |
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Term
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Definition
| Excitable cells that transmit electrical signals |
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Term
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Definition
| Cells that surround and wrap neurons |
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Term
| Supporting cells: Neuroglia |
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Definition
| Provide a supportive scaffolding for neurons. Segregate and insulate neurons. Guide young neurons to the proper connections. Promote health and growth |
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Term
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Definition
| Most abundant, versatile, and highly branched glial cells. Cling to neurons and their synaptic endings, and cover capillaries |
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Term
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Definition
| Support and brace neurons. Anchor neurons to their nutrient supplies. Guide migration of young neurons. Participate in information processing in the brain. Control the chemical environment. |
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Term
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Definition
| Small, ovoid cells with spiny processes. Migrate toward injured neurons. Phagocytize microorganisms and neuronal debris |
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Term
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Definition
| Range in shape from squamous to columnar. They line the central cavities of the brain and spinal column. Separate the CNS interstitial fluid from the cerebrospinal fluid in the cavities |
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Term
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Definition
| branched cells that wrap CNS nerve fibers |
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Term
| Schwann cells (neurolemmocytes) |
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Definition
| surround fibers of the PNS. Vital to regeneration of damaged peripheral nerve fibers |
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Term
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Definition
| Surround neuron cell bodies with ganglia |
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Term
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Definition
| Structural units of the nervous system |
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Term
| Characteristics of neurons |
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Definition
| Composed of a body, axon, and dendrites. Long-lived (up to 100 years), amitotic, and have a high metabolic rate dependent on continuous supply of oxygen and glucose |
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Term
| Neuron plasma membrane functions in |
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Definition
| Electrical signaling. Cell-to-cell signaling during development |
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Term
| Nerve Cell Body (Perikaryon or Soma) |
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Definition
| Contain the nucleus and a nucleolus. Major biosynthetic center. IS the focal point for the outgrowth of neuronal processes. Has well-developed Nissl bodies (rough ER). Contains an axon hillock - cone shaped area from which axons arise |
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Term
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Definition
| Cone shaped area from which axons arise |
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Term
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Definition
| Armlike extensions. Called tracts in the CNS nerves in the PNS. |
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Term
| Two types of soma processes |
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Definition
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Term
| Dendrites of Motor Neurons: Summary |
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Definition
| Short, tapering and diffusely branched processes. THey are the receptive, or input, regions of the neuron. Electrical signals are conveyed as graded potentials (not action potentials) |
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Term
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Definition
| Slender processes of uniform diameter arising from the hillock. Long axons are called nerve fibers. Usually there is only one unbranched axon per neuron. Rare branches, if present, are called axon collaterals. |
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Term
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Definition
| Branched terminus of an axon |
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Term
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Definition
| Branched terminus of an axon |
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Term
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Definition
| Generate and transmit action potentials. Secrete neurotransmitters from the axonal terminals. Movements along axons occurs in two ways |
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Term
| Way movement along axons occurs: |
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Definition
Anterograde: Toward axonal terminal
Retrograde: Away from axonal terminal |
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Term
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Definition
| Whitish, fatty (protein-lipoid), segmented sheath around most long axons |
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Term
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Definition
| Protect the axon, Electrically insulate fibers from on another. Increase the speed of nerve impulse transmission |
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Term
| Myelin Sheath and Neurilemma: Formation |
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Definition
| Formed by Schwann cells in the PNS. |
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Term
| Myelin Sheath Formation: Schwann Cell |
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Definition
| Envelopes an axon in a trough. Enclose the axon with its plasma membrane. Has concentric layers of membrane that make up myelin sheath. |
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Term
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Definition
| remaining nucleus and cytoplasm of a Schwann cell |
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Term
| Nodes of Ranvier (Neurofibral Nodes) |
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Definition
| Gaps in the myelin sheath between adjacent Schwann cells. They are the sites where axon collaterals can emerge |
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Term
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Definition
| Schwann cell surrounds nerve fibers but coiling does not take place. Schwann cells partially enclose 15 or more axons |
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Term
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Definition
| Both myelinated and unmyelinated fibers are present. Myelin sheaths are formed by oligodendrocytes. Nodes of Ranvier are widely spaced. There is no neurilemma |
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Term
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Definition
| White Matter, Gray Matter |
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Term
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Definition
| Dense collections of myelinated fibers |
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Term
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Definition
| mostly soma and unmyelinated fibers |
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Term
| Neuron Classification: Structural |
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Definition
Multipolar - three or more processes
Bipolar - two processes (axon and dendrite)
Unipolar - single, short process |
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Term
| Neuron Classification: Functional |
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Definition
Sensory (afferent) - transmits impulses toward the CNS
Motor (efferent) - carry impulses away from the CNS
Interneurons (association neurons) - shuttle signals through CNS pathways |
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Term
| Changes in membrane potential: Depolarazition |
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Definition
| A reduction in membrane potential (toward zero). Inside of the membrane becomes less negative than the resting potential. Increasing the probability of producing a nerve impulse |
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Term
| Changes in Membrane Potential: Hyperpolarization |
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Definition
| An increase in membrane potential (away from zero). Inside of the membrane becomes more negative than the resting potential. Reduces the probability of producing a nerve impulse |
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Term
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Definition
| Found in dendrites. Decrease over distance. Magnitude varies with stimulus. Small area of membrane becomes depolarized: Positive ions in the area move toward negative ions and signal "spreads"; there is not consistent "passing" of ions in and out of cell |
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Term
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Definition
| Brief reversal of membrane potential with a total amplitude of about 100 mV. Occurs in muscle cells and axons of neurons. Does not decrease in magnitude over distance. Principal means of long-distance neural communication |
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Term
| Action Potential Creation: States |
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Definition
| Resting, Depolarization, Threshold, Repolarization, Hyperpolarization |
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Term
| Action Potential Creation: Resting state |
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Definition
| Sodium and potassium channels closed |
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Term
| Action Potential Creation: Depolarization |
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Definition
| Sodium channels open causing a cascade effect opening more sodium channels |
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Term
| Action Potential Creation: Threshold |
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Definition
| Critical level where sodium channel cascade drives membrane potential postive (+30mV). 1ms - AP created |
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Term
| Action Potential Creation: Repolarization |
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Definition
| Sodium gates close and potassium gates open - potassium leaves the cell |
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Term
| Action Potential Creation: Hyperpolarization |
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Definition
| "Undershoot' - So much potassium leaves the cells that it is more negative than at rest |
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Term
| Conduction velocities of axons |
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Definition
| Conduction velocities vary widely among neurons |
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Term
| Rate of impulse propagation is determined by |
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Definition
| Axon diameter, presence of a myelin sheath |
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Term
| Conduction Velocities of Axons - Axon diameter function |
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Definition
| The larger the diameter, the faster the impulse |
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Term
| Conduction Velocities of Axons - Presence of a myelin sheath |
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Definition
| Myelination dramatically increases impulse speed |
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Term
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Definition
| Current passes through a myelinated axon only at the nodes of Ranvier. Voltage-gated Na+ channels are concentrated at these nodes. Myelin sheaths insulate and prevent leakage of charge. Saltatory conduction in myelinated axons is about 30 times faster. Action potentials are triggered only at the nodes and jump from one node to the next. Much faster that conduction along unyelinated axons |
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Term
| AP in a bare plasma membrane without voltage gated channels |
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Definition
| As on a dendrite, voltage decays because current leaks across the membrane. |
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Term
| AP movement through an unmyelinated axon |
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Definition
| Voltage-gated Na+ and K+ channels regenerate the action potential at each point along the axon, so voltage does not decay. Conduction is slow because movements of ions and of the gates of the channel proteins take time and must occur before voltage regeneration occurs |
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Term
| AP movement through a myelinated axon |
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Definition
| Myelin keeps current in axons, voltage doesn't decay much, APs are generated only in the nodes of Ranvier and appear to jump rapidly from node to node |
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Term
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Definition
| Axodendritic, Axosomatic, Axoaxonic, Dendrodendritic, Dendrosomatic |
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Term
| Types of Synapses - Axodendritic |
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Definition
| synapses between the axon of one neuron and the dendrite of another |
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Term
| Types of Synapses - Axosomatic |
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Definition
| synapses between the axon of one neuron and the soma of another |
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Term
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Definition
| Less common than chemical synapses. Correspond to gap junctions found in other cell types - connexins - electrically coupled. Important in the CNS. Synchrony |
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Term
| Electrical Synapses: Importance in the CNS |
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Definition
| Arousal from sleep, mental attention,k emotions and memory |
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Term
| Electrical Synapses: Synchrony |
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Definition
| all neurons in the area are interconnected and working together |
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Term
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Definition
Specialized for the release and reception of neurotransmitters. Typically composed of two parts:
Axonal terminal of the presynaptic neuron, which contains synaptic vesicles
Receptor region on the dendrite(s) or soma of the postsynaptic neuron |
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Term
| Synaptic Cleft: What is it? |
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Definition
| Fluid filled spaced separating the presynaptic and post synaptic neurons. |
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Term
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Definition
| Prevents nerve impulses from directly passing from one neuron to the next |
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Term
| Synaptic Cleft: Transmission |
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Definition
| Chemical event, not electrical. Ensure unidirectional commnunication between neurons |
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Term
| Synaptic Cleft: Information Transfer Step 1 |
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Definition
| Nerve impulses reach the axonal terminal of the presynaptic neuron and open Ca2+ channels |
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Term
| Synaptic Cleft: Information Transfer Step 2 |
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Definition
| Neurotransmitter is released into the synaptic cleft via exocytosis in response to synaptotagmin |
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Term
| Synaptic Cleft: Information Transfer Step 3 |
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Definition
| Neurotransmitter crosses the synaptic cleft and binds to receptors on the postsynaptic neuron |
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Term
| Synaptic Cleft: Information Transfer Step 4 |
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Definition
| Postsynaptic membrane permeability changes, causing an excitatory or inhibitory effect |
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Term
| G Protein-Linked Receptors: Mechanism |
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Definition
| Responses are indirect, slow, complex, and often prolonged and wide spread. Second messengers open or close ion channels, active kinase enzymes, phoporylate channel proteins, activate genes and induce protein synthesis |
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Term
| Termination of Neurotransmitter effects: |
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Definition
Neurotransmitter bound to a postsynaptic neuron:
Produces a continuous postsynaptic effect
Blocks reception of additoinal "messages"
Must be removed from its receptor |
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Term
| Termination of Neurotransmitter effects: Removal of neurotransmitters |
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Definition
| Occurs when they are degraded by enzymes, are reabsorbed by astrocytes or the presynaptic terminals, diffuse from the synaptic cleft |
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Term
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Definition
| Neurotransmitter must be released, diffuse across the synapse, and bind to receptors. Time to do this (.3-5 ms). Rate-limiting step of neural transmission |
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Term
| Neurotransmitters: What are they? |
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Definition
| Chemical used for neuronal communication with the body and the brain. 50 different have been identified. Classified chemically and functionally. |
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Term
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Definition
| First neurotransmitter identified and best understood. Released at neuromuscular junction. Synthesized and enclosed in synaptic vesicles. Degraded by the enzyme acetylcholinesterace. Released by All neurons that stimulate skeletal muscle. Some neurons in the autonomic nervous system |
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Term
| Neurotransmitters: Biogenic Amines |
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Definition
| Catecholamines, Indolamines. Broadly distributed in the brain. Play roles in emotional behaviors and our biological clock |
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Term
| Neurotransmitters: Catecholamines |
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Definition
| dopamine, norepinephrine, epinephrine |
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Term
| Neurotransmitters: Indolamines |
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Definition
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Term
| Neurotransmitters: Amino acids |
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Definition
GABA (gamma-aminobutyric acid)
Glycine
Aspartate
Glutamate
Found only in the CNS |
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Term
| Neurotransmitters: Peptides |
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Definition
Substance P - mediator of pain signals
Beta endorphin, dynorphin, and enkephalins
Act as natural opiates, reduce pain perception
Bind to the same receptors as opiates and morphine |
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Term
| Neurotransmitters: Novel Messengers |
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Definition
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Term
| Neurotransmitters: Novel Messengers - ATP |
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Definition
Found in the CNS and PNS
Produces excitatory or inhibitory responses depending on receptor type
Induces Ca2+ wave propagation in astrocytes
Provokes pain sensation |
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Term
| Neurotransmitters: Nitric Oxide (NO) |
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Definition
| Involved in learning and memory. Carbon monoxide is a main regulator of cGMP in the brain |
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Term
| Functional Classification of Neurotransmitters |
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Definition
| Excitatory and Inhibitory |
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Term
| Functional Classification of Neurotransmitters: Excitatory |
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Definition
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Term
| Functional Classification of Neurotransmitters: Inhibitory |
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Definition
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Term
| Functional Classification of Neurotransmitters: Acting as both |
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Definition
Effects determined by the receptor rype of the postsynaptic neuron. ex: acetylcholine
Excitatory at neuromuscular junctions with skeletal muscle
Inhibitory in cardiac muscle |
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Term
| Neurotransmitter Receptor Mechanisms |
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Definition
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Term
| Neurotransmitter Receptor Mechanisms: Direct |
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Definition
| Neurotransmitters that open ion channels. Promote rapid responses. eg, ACh and amino acids |
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Term
| Neurotransmitter Receptor Mechanisms: Indirect |
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Definition
| Neurotransmitters that act through second messengers. Promote long lasting effects. eg, biogenic amines, peptides, and dissolved gases |
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