A and P ch 11

This part of neural tissue consists of the spinal cord and brain
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Terms in this set (86)
Site of neuronal communication with other cellsSynapseHow many cells meet at every synapse?2This part of the synapse sends a messagePresynaptic cellThis part of the synapse receives a messagePost synaptic cellCommunication between synapses is usually accomplished by:NeurotransmittersThese neurons from the Afferent division of the PNS and deliver sensory information to the CNSSensory neuronsThese are efferent neurons which carry instructions from CNS to peripheral effectorsMotor neuronsThese neurons outnumber all other types of neurons combined. Are responsible for the distribution of sensory info and the coordination of motor activityInterneuronsCells which assist neuronal function but which are not neuronsNeurogliaHow many types of neuralgia does the CNS have?4What are the four types of neuroglia?Ependymal cells, astrocytes, oligodensrocytes, microgliaThis type of neuroglia lines the central canal of the spinal chord and the ventricles of the brainEpendymal cellsThese type of neuroglia maintain the blood/brain barrier by wrapping around CNS capillaries; control the chemical exchange between the blood and interstitial fluidAstrocytesName 3 qualities of astrocytesThese type of neuroglia create a 3D framework for the CNS structural framework, repair damages neural tissue and control composition of interstitial fluidThese type of neuroglia help to form myelin sheaths around axonsOligodendrocytesThis is the myelinated part of an axonInternodeThese are small gaps in myelinNose/ nodes of ranvierBranches of axons begin hereNodesWhite matter isMyelinated axonsGrey matter isNon myelinated axonsThese small cells/neuroglia perform macrophage functionMicrogliaThese cells in the PNS surround neuron cell bodies in the gangliaSatellite cellsA cluster of neuronal cells (PNS)GangliaThese cells in the PNS regulate the environment similar to astrocytes in the CNSSatellite cellsThese cells in the PNS form a sheath around peripheral axons (a series of these cells are required to myelinated axons along the entire length)Schwann cellsCytosol and extra cellular fluid differ greatly inIonic composition (transmembrane potential)This has high concentrations of K and negatively charges proteinsCytosolThis has high concentrations of Na and Cl- ionsExtra cellular fluidThe transmembrane potential of an undisturbed cellResting potentialThe inner surface of the cell has an excess of this type of charge compared to the outer surfaceNegativeIntercellular concentrations of potassium ions is ______; therefore they tend to________.High; move out of the cell through open channelsWhat is the concentration if sodium ions inside and outside of the cell membraneExternal concentration is high, internal is lowThe transmembrane potential at which there is no net movement across the cell membrane for that ionEquilibrium potentialWhat are the three classes of membrane channelsChemically regulated channels, voltage regulated, mechanically regulatedThis type of membrane channel opens or closes when they bind to specific chemicalsChemically regulated channelsWhat is an example of a chemically regulated channelReceptors which bind acetylcholine at the neuromuscular junctionWhere are chemically regulated channels most abundant?In dendrites and cell bodies of neuronsThis type of membrane channel is characteristic of areas of excitable membrane capable of generating and conducting an action potentialVoltage regulated channelsGive an example of a voltage regulated channelAxons of neurons and the sarcolemma of skeletal muscle fibersVoltage regulated channels open or close in response toChanges in transmembrane potentialThis type of membrane channel opens of closes in response to physical distortion of a membrane surfaceMechanically regulated channelsWhen are most gated channels closed?At resting potentialGraded potentials are sometimes calledLocal potentialsChanges in transmembrane potential which cannot spread far from the area surrounding the site of the stimulusGraded potentials/ local potentialsA shift in the resting transmembrane potential towards 0mv is calledDepolarizationSodium ions nice parallel to the inner membrane and spread outLocal currentThe degree of polarization ______ with the distance from initial depolarizationDecreasesWhy does the degree of polarization decrease with distance from initial depolarization?Some sodium ions leak back out and the original stimulus decreases in power with distanceWhen the original chemical stimulus is removed, what happens to the transmembrane potential?It returns to resting levels (repolarization)Develops in response to a graded potential which spreads to the initial segment of the axon from the adjacent hillock and spreads along the entire length of the axonAction potentialsAs the transmembrane potential approaches 30mv what happens to the sodium channelsInactivation of the gates of the sodium channels begin closing (sodium channel inactivation)While sodium channels are closing, what happens simultaneously?Voltage regulated potassium channels are opening and potassium flows out of the cell and repolarization occursWhen does potassium cease to flow out?Once transmembrane potential has reached -70mvWhen tm potential reaches -70mv, what happens?Sodium potassium pump returns intercellular and extracellular levels of sodium and potassium to pre stimulation levelsPeriod from the time an action potential begins until the time that normal resting potential has stabilized; membrane will not respond to additional depolarizing stimuliRefractory periodWhen action potential moves across surface of membrane in a series of tiny stepsContinuous propagationWhen the local current skips the internodes and moves to the closest node. Action potential "jumps" from node to node. Very rapid.Saltatory propagationHow are axons classified?According to diameter, speed of propagationThis type of axon is the largest, myelinated and carry action potentials at 140 meters per second. Carry info to the CNS about balance, skin sensations (touch). Motor neurons which send their commands to muscles also use this type of axon fiberType AThis type of axon is smaller, myelinated, action potentials at 18 meters per second, and carry commands to smooth muscle, cardiac muscle, glandsType BThis type of axon is unmyelinated and carries action potential at 1 meter per seconeType CThis type of synapse is very rare in the PNS and CNSElectrical synapseThis type of synapse is the most abundant type of synapseChemical synapseThis is a type of chemical synapseAcetylcholineThis type of neurotransmitter causes depolarization and promotes the generation of action potentialsExcitatory neurotransmittersThis type of neurotransmitter causes hyperpolarizationInhibitoryWhen extracellular calcium enters the synaptic cleft it triggersExocytosis of acetylcholineWhen acetylcholine binds to the receptors, what happens?It depolarizers the post synaptic membraneWhat is the chemical which removes acetylcholine?AcetylcholinesteraseThis is an excitatory neurotransmitter in parts of the ANSNorepinephrineThis is a CNS neurotransmitter which may have excitatory or inhibitory effectsDopamineThis is a CNS neurotransmitter whose imbalance can cause chronic depression and the presence of it in synapses can relieve these depression signalsSerotoninThis type of neurotransmitter is usually inhibitoryGABA- gamma amino butyric acidAlters neurotransmitter release by the presynaptic neuron or alter the response to neurotransmitter by post synaptic neuronsNeuromodulatorsThese neuromodulators have effects similar to opioids because they bind to the same group of post synaptic receptorsOpioidsWhat is an important function of neuromodulators?Function in pain relief by inhibiting the release of neurotransmitter say the synapses which transmit pain sensations