BIOL 3800 1nd Edition Lecture 5 Outline of Last Lecture I. IntroductionII. Structure/Organization of MembraneA. Plasma MembraneB. Membrane CompositionIII. Crossing MembraneA. DiffusionB. OsmosisIV. Mechanism Transmembrane MovementsA. PressureB. DiffusionC. Active TransportV. Vesicle Membrane TransportA. EndocytosisB. ExocytosisC. PinocytosisD. PhagocytosisVI. Cell to Cell JunctionsVII. CAMSOutline of Current Lecture I. NeuronsA. Major players in Nervous SystemB. Communicate via electrical and Chemical SignalsC. Most Electrically ExcitableD. All Neurons and Glial Cells (supporting cells) make up nervous systemE. 3 Important Reasons Thoroughly StudiedII. Neuronal Structure and FunctionThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.A. 2 Ways to Differentiate Neuronal RegionsB. Neuron StructureC. Little Correlation Between Neuronal Complexity and PhylogenyIII. Transmission of Signals in Single NeuronA. Spike-Initiating ZoneB. Physiological BehaviorIV. Transmission of Signals Between NeuronsA. Afferent fibersB. InterneuronsC. SynapsesD. Effector NeuronsE. Neuronal Circuit: Afferent, Interneurons, EfferentF. Presynaptic/Postsynaptic NeuronsG. Neuronal CircuitV. Organization of Nervous SystemA. Sensory NeuronsB. Motor NeuronsC. SomataD. Glial CellsCurrent LectureNeuronal Structure and FunctionI. Neurons: nerve cellsA. Major player in nervous systemB. Communicate via electrical and chemical signalsC. Most electrically excitable1. Electrical signals can be carried along length of cell and can do this without loss of signal strengthD. All neurons and glial cells(supporting cells) make up nervous systemE. 3 Important Reasons Thoroughly Studied1. Electrical signals linked to physical science2. Similar to all animals3. “sophisticated information processing” remarkably depends on only small number physical and chemical propertiesII. Neuronal Structure and FunctionA. 2 Ways to Differentiate Neuronal Regions1. Specific roles within the cell or specializations2. Subcellular architectureB. Neuron Structure1. Each has soma: cell bodya. Soma responsibility = cell metabolic maintenance2. 2 main processesa. Dendritesi. Extend from soma and are branched refer to (fig 5-1) for visualii. They gather signals sent from other neurons and transmit them to somab. Axons (a nerve fiber) BE CAREFUL NEVER CALL AXON A NERVE!!i. Extensions of soma that carry signals away from itii. Longer than dendritesiii. Also note axon is incredibly long compared to size of nerve celliv. Can carry information without loss of strength and accuracyv. Many vertebrate axons surrounded by myelin sheath (these are supporting cells which provide and insulating layer surrounding length of cell)vi. Regeneration of axon IN MAMMALS takes place only in peripheral nerves of nervous systemRegeneration of axon IN COLD BLOODED VERTEBRATES can take place in central nervous system- Conversely many invertebrates readily regenerate damaged neurons(reason can regenerate limbs and we can’t3. Other terms to Knowa. Axon hillock: area between axon and the soma (also where spike initiating zone)b. Nerve: a bundle of axons or dendrites emanating from CNSc. Collaterals: one of branches that bifurcates (divide into 2 branches) off primary axond. Teledendrons or terminal arborization: any terminal or smaller branches of an axon that terminate with ending that release neurotransmitterse. Axon terminals: distal termination of branches of axon boutons: swelling of axons at synapse (they also contain vesicles)C. Little Correlation Between Neuronal Complexity and Phylogeny: evolutionary history of organism (simplicity or complexity of organism)1. Although simple organisms have simple structure some complex organisms have simple structure as well2. Some complex organisms have complex structure as do some simpler organism like insects which also have complex structureIII. Transmission of Signals in Single NeuronA. Spike-initiating Zone: brings all the many signals from multiple neurons to determine whether neuron will start its own signal1. This signal the neuron decides to make is called Action Potential, AKA spikes or nerveimpulses2. This zone usually located at axon hillockB. Physiological Behavior1. Physiological behavior of neuron determined by passive electrical properties (i.e resistance, capacitance)2. Also determined by active electrical propertiesa. Properties allow neurons to transmit these signals without loss of signal strengthb. The properties depend on voltage-gated ion channels located in plasma membrane as well as specific proteinsC. Ion Channels Localized 1. Not evenly distributed but at places with specialized signaling functionsIV. Transmission of Signals Between NeuronsA. Afferent Fibers: axon of a sensory neuron1. Conducts signal inward toward CNS (central nervous system)B. Interneurons: link other neurons within CNS1. Carry info. between neuronsC. Synapses: info. transmitted between neurons and/or other target cells via this structureD. Effector neurons: transfer info from processing areas of CNS outward to effectors1. If animal going to respond to sensory neurons need effector neuronsE. Afferent neuron, Interneurons, Effector Neurons all make up neuronal circuitF. A cell transfers info to neuron called presynapticA cell that receives info called postsynapticG. Neuronal Circuit1. Information carried by alternation between chemical synaptic signals (neurotransmitter molecules) & electrical action potentials2. All- or-none signals that are unchanging (electrical AP’s)Graded signals amplitude varies (chemical signals)V. Organization of Nervous SystemA. Sensory Neurons1. Transform energy of stimulus into electrical signal or APB. Motor neurons1. Not named because necessarily control bodily movement but considered any neurons that supply gland cells with nerves and other effector targetsC. Somata1. Cell bodies MOSTLY contained within CNSa. CNS consist of brain and spinal cord2. Invertebrates a. Brain in head and somata called Ganglia located along nerve cordb. Vertebrates have Ganglia located outside CNS and nerve cord is spinal cordD. Glial Cells AKA neuroglia (fill space between neurons) except for fluid-filled thin space that separates glial and neuronal membranes1. Glial Cells don’t produce action potentials2. wrap axons in myelin sheath this helps protect axon3. 4 main types Glial cellsa. Astrocytes: star