BIOL 112 1st Edition Lecture25Outline of Last Lecture I. Intro to Nervous SystemsII. NeuronsIII. Action PotentialIV. Initial ResponseOutline of Current LectureV. Communication between NeuronsVI. Types of NeuronsVII. Nervous SystemsVIII. AnatomyIX. Somatic vs. AutonomicCurrent LectureI. Communication between Neurons•Action potential doesn’t jump from one neuron to another•Information gets from cell to cell at specialized regions called synapses•info is communicated through a chemical signal (not touch or fu-sion)•information only moves in one direction across a synapse•Synaptic Structures•Pre-synaptic cell/membraneThese 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.•Post-synaptic cell/membrane•Synaptic Cleft•Neurotransmitter - packaged in secretory vesicles•synthesized in the cell body•moved down length of axon to site of use in synapse•each neuron type makes only one type of neurotransmitter•Synaptic Function•Action potential propagates along axon of pre-synaptic neuron to end at synapse•action potential stimulates some of the neurotransmitter vesicles to fuse with plasma membrane, releasing their contents into cleft•Neurotransmitter chemicals diffuse across cleft and contact recep-tor molecules in post-synaptic cell surface•enzymes in cleft destroy neurotransmitter•Post-synaptic Summation•Post-synaptic cell receives input from many other cells, both exci-tatory and inhibitory input •Decision about whether or not post-synaptic cell will initiate an action potential is made at the axon hillock •Distance of synapses from the hillock influence how much depo-larization or hyperpolarization affects decision: spatial summa-tion •Timing of synapse activ-ities influence decisionin hillock: temporalsummationII. Types of Neurons•Three basic types:•sensory neurons - input of chemical or physical information•interneurons - integrate information•motor neurons - output of response, stimulate activity in muscles or glands•combination of all three make nervous systemsIII. Nervous Systems•combinations of sensory, inter-, and motor neurons•detect stimuli, integrate information about stimuli and produce ap-propriate response•simplest arrangement: Reflex Arc•One of each neuron participates •Sensory neuron detects stimulus (e.g., pain) •Interneuron receives signal and communicates information for-ward (to many other neurons) •Motor neuron receives signal from interneuron and stimulates muscle to contract•Most of behavior from nervous systems consists of elaborations of these kinds of reflex arcs•Brain stimulates or inhibits groups of reflexes to produce various kinds of motor behaviorIV. Anatomy•Central Nervous System (CNS)•Brain and spinal cord - CNScells are entirely within thesestructures, high level integra-tion of information input andoutput•grey matter - cell bodies, ax-ons, dendrites•white matter - myelinated ax-ons only•Peripheral Nervous System (PNS)•portions of neurons outside spinal cord or brain, input and output•Somatic and Autonomic (sympathetic and parasympathetic)V. Somatic vs. Autonomic•Somatic Nervous System•Sensory Neurons (afferent nerves) - touch, pain, heat, cold, etc.•dorsal root ganglia - on either side of spinal cord, cell bodies lo-cated here•motor neurons (efferent nerves) - stimulate contraction of skeletal muscles, “conscious” activities, cell bodies are located in grey mat-ter•Autonomic Nervous System•Visceral sensory neurons and motor neurons for “involuntary” ac-tivities in body: heart beat rate, muscles in digestion, hormone se-cretion, microcirculation, etc.•Cell bodies may or may not be in spine, many are located in sets of ganglia outside spinal cord, not all synapses in spine•Two parts:•Sympathetic and Parasympathetic•Both connected to same structures•Have antagonistic effects: one stimulates, the other inhibits•Example: heart beat rate - sympathetic speeds heart up, parasympathetic slows heart down•Sympathetic Nervous System•Epinephrine and Norepinephrine are usual neurotransmitters•promotes activities that increase body energy and tension•synapses in ganglia along ventral side of vertebra•dilates pupils, inhibits salivation, accelerates heart rate, relaxesbladder•Parasympathetic Nervous System•Acetyl choline is usual neurotransmitter•Promotes activities that conserve body energy and relax body•Synapses are in or near organs effected; ganglia are in organs•contracts pupils, stimulates salivation, decelerates heart rate, contracts