BIO 311D 2nd Edition Lecture 32 Outline of Last Lecture I Ion channels and Membrane Potential II Action Potential is all or none III Chemical Synapse Outline of Current Lecture I Chemical Synapses II Neuromuscular junction III Neuron networks Current Lecture I II Chemical Synapses A Membrane communication at the end of an axon triggers the releases of neurotransmitters into the synapse NT binds receptor causing response a Signaling specific signal and receptor b Clearing the synapse to prevent from over simulating Neuromuscular junctions A Some neurotransmitter receptors are ligand gated channels a The AChR protein is a ligand gated Na ion channel b Some GABA receptors are ligand gated Cl ion channels B Some neurotransmitter receptors activate signal transduction pathways a Could open ion channels etc C IClicker Question 1 Into cell 2 Into cell 3 4 5 Hyperpolarize III Neuron Networks A Most neurons receive multiple excitatory postsynaptic potentials EPSPs to reach threshold for an action potential a This decision making process is called summation b Depolarization sufficient to get to threshold to lead to action potential B Some neurotransmitters cause postsynaptic cell to hyperpolarize These inhibitory postsynaptic potentials IPSPs reduce the chance of an action potential The cell body integrates these signals C Sensory neurons take non neural signals and turn them into neural responses a Responds to change in pressure b Responds to heat c Responds to taste receptor i e small molecule of sugar d Responds to light e Their output can talk to neurons such as interneurons other interneurons motor neurons D How does the action potential go along the entire length of the axon That is how is it propagated without any loss of magnitude a Action potentials depolarization wave followed by receptor travel along axons with no loss of signal amplitude b Axon membrane E The sodium ion concentration the neuron membrane is usually much higher outside than inside Which of the following contribute to this steep gradient a Voltage gated sodium channels b Ligand gated sodium channels c Sodium potassium pumps Channels are passive and do NOT create a gradient F Stimulation at the neuromuscular junction generates an action potential on the muscle membrane that triggers the release of Ca stored in the sarcoplasmic reticulum flooding the cytosol of the sarcoplasm where the muscle fibers lie G Skeleton muscles made of bundles of overlapping fibers each with numerous thick myosin fibers and thin actin fibers a Actin microfilaments Myosin motor protein b Sliding filament mechanism 1 Overlapping contraction 2 Separation lengthen retraction 3 ATP hydrolysis provides the energy 4 Myosin is a motor protein When phosphorylated in ATP hydrolysis it changes shape 5 Activated myosin thick filament binds to action thin filament forming a cross bridge and pulling shoving the thin filament 6 Depolarization opens voltage gated Ca channels calcium ions trigger contraction H Knee Jerk Reflex 1 Neuron that releases acetylcholine acetylcholine receptors open sodium ion channels 2 Muscle cell that contracts when acetylcholine binds to its receptors 3 Neuron that when stimulated inhibits the release of acetylcholine into its synapse 4 Neuron that an receive sensory information touch stimulus 5 Neuron that releases neurotransmitters that depolarize the post synaptic membrane Pathway 4 5 1 3 2
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