Neurons and NeurotransmittersRVS Chatianya KoppalaAssistant Professor Lovely Professional University
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Nervous System
Central nervous system (CNS):BrainSpinal cord
Peripheral nervous system (PNS):Sensory neuronsMotor neurons (somatic and autonomic)
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Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Central Nervous System (CNS)BrainSpinal CordPeripheral Nervous System (PNS)Sensory NeuronsMotor NeuronsSomatic Nervous Systemvoluntary movements via skeletal muscles
Autonomic Nervous Systemorgans, smooth muscles
Sympathetic- Fight-or-Flight responsesParasympathetic - maintenanceThe Nervous SystemThe Nervous System
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Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Divisions of the autonomic nervous system
*Figure 3.20 on page 89The sympathetic division of the nervous system prepares the body for action, whereas the parasympathetic returns it to a resting state.
The Nervous SystemA physical organ system like any other
2 main kinds of cells NeuronsGlia
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Basic units of the nervous system Receive, integrate, and transmit information Operate through electrical impulses Communicate with other neurons through chemical signals More about neurons and neuronal anatomy laterNeurons
Glial cells100 billion neurons10x more glial cellsGlial cellsSupport neurons (literally, provide physical support, as well as nutrients)Cover neurons with myelinClean up debrisHousewives
Regulate external environment (ions, etc.) Most abundant glial cell May contribute to blood-brain barrier
and to synapsesAstrocytes
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Three main types of neuronsSensory Neurons
Interneurons
Motor Neurons
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Sensory (Afferent) vs. Motor (Efferent)
e.g., skine.g., muscleGrays Anatomy 38 1999sensory (afferent) nervemotor (efferent) nerveNeurons that send signals from the senses, skin, muscles, and internal organs to the CNS Neurons that transmit commands from the CNS to the muscles, glands, and organs
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The Withdrawal Reflex
*Figure 2.5B from:Kassin, S. (2001). Psychology, third edition. Upper Saddle River, NJ: Prentice Hall.
Neuron Anatomy and Neural Communication
Neurons
Axon of anotherneuronDendrites of another neuron
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Neural AnatomyDendritethe bushy, branching extensions of a neuron that receive messages and conduct impulses toward the cell bodyAxonthe extension of a neuron, ending in branching terminal fibers, through which messages are sent to other neurons or to muscles or glands
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Neural Anatomy and communicationSynapsejunction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neurontiny gap at this junction is called the synaptic gap or cleftSynapse movie
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Specific Parts: The NeuronStructure
*Figure 2.6 from:Kassin, S. (2001). Psychology, third edition. Upper Saddle River, NJ: Prentice Hall.Source:
Specific Parts: The Neuron FunctionNeurons = 3 functions: Reception, Conduction, Transmission1.3.2.
*Figure 2.6 from:Kassin, S. (2001). Psychology, third edition. Upper Saddle River, NJ: Prentice Hall.Source:
Action PotentialWhen dendrites stimulated, the delicate balance is alteredMembrane breaks downPositively charged ions rush in (depolarization)Charge = less negativeCauses release of chemicals from terminal buttons
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W. W. Norton
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Relay RaceAction Potential starts at dendriteThrough cell bodyDown AxonAxon TerminalsHow does it get to the next cells dendrites?
Neurons dont touchSynapse = millionth inch gapIn synapse = vesicles w/ neurotransmittersChemical messengers that transmit info
CommunicationImpulse releases neurotransmitter from vesicles
Neurotransmitter enters synaptic gap
Neurotransmitter binds to receptors on the receiving neuron
*Figure 2.7 from:Kassin, S. (2001). Psychology, third edition. Upper Saddle River, NJ: Prentice Hall.Source:
Myelin Sheath
Fatty material made by glial cellsInsulates the axonAllows for rapid movement of electrical impulses along axonNodes of Ranvier: gaps in myelin sheath where action potentials are transmittedMultiple sclerosis is a breakdown of myelin sheathSpeed of neural impulse Ranges from 2 200+ mph
Myelinization clipMyelin conduction clip
Neurotransmitters
chemical messengers that traverse the synaptic gaps between neuronswhen released by the sending neuron, neurotransmitters travel across the synapse and bind to receptor sites on the receiving neuron, thereby influencing whether it will generate a neural impulse
Neurotransmitters (>60)Acetylcholine (ACh)1st substance identified as NTLinks motor neurons and muscles (contract or relax)e.g. curare vs black widow spiderAlso involved in memory, learning, sleep, dreaming
(acetylcholine movie)Endorphins (the brains own morphine)1973 injected rats with morphineBound like NTsBrain had receptors for exogenous substance?Brain must produce its own morphineReleased during pain and discomfort
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More neurotransmitters Receptor binding movie
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THANK YOU
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*Figure 3.20 on page 89The sympathetic division of the nervous system prepares the body for action, whereas the parasympathetic returns it to a resting state.*
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*Figure 2.5B from:Kassin, S. (2001). Psychology, third edition. Upper Saddle River, NJ: Prentice Hall.*
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*Figure 2.6 from:Kassin, S. (2001). Psychology, third edition. Upper Saddle River, NJ: Prentice Hall.Source:*Figure 2.6 from:Kassin, S. (2001). Psychology, third edition. Upper Saddle River, NJ: Prentice Hall.Source:*
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*Figure 2.7 from:Kassin, S. (2001). Psychology, third edition. Upper Saddle River, NJ: Prentice Hall.Source:*
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