BIOPSYCH 0505 1 Edition nd Lecture 4 Outline of Last Lecture Cells in the Nervous System I Supportive cells for every neuron there are 10 support cells A Glial cells 1 Astrocytes B Oligiodendrocyte C Schwann cell satellite cells II Types of Neurons A Bipolar B Interneuron C Multipolar neuron D Unipolar III Structure of the neuron A Soma B Dendrites C Axon D Terminal buttons E Myelin sheath F The movement IV Resting potential 70 millivolts A Ions 1 Positively charged 2 Negatively charged B What happens during resting potential C Sodium potassium pump V Action Potential A Electrical impulse B The axon C Threshold D Refractory period These 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 E F G H Repolarization Hyperpolarization All or nothing principle Self propagation of polarization Outline of Current Lecture I Synapse three sections A Pre synaptic membrane 1 Reuptake 2 Enzymatic Degradation II Synaptic gap cleft III Post synaptic membrane extension from dendrite A Ionotropic receptor B Metabotropic receptors C Post synaptic potentials 1 Communication between neuron IV Generation of action potential or hyperpolarization A Temporal Summation B Spatial Summation C EPSP and IPSP cancellation Current Lecture I Synapse three sections A Pre synaptic membrane membrane at the end of the axon where the terminals are 1 Presynaptic event occurs with the synthesis of the neurotransmitters either in the terminal button itself smaller molecules or in the cell body larger molecules 2 They are then transported through the axon to the terminals so they are available for release 3 All the neurotransmitters are inside a vesicle the neurotransmitters are wrapped in vesicles so that they can bind with the membrane easily and to prevent them from breaking down 4 When the action potential positive charge reaches the terminal some migrate towards the pre synaptic membrane 5 Once it reaches the calcium which opens up the channels the membrane pinches off and is used to create new vesicles so that the membrane does not grow too big 6 Reuptake II III a Near the pre synaptic membrane neurotransmitters are removed when they are not bound to receptors 1 Enzymatic Degradation b Enzymes are released by the pre synaptic membrane whose purpose is to break down the neurotransmitter molecules into inactive parts so that they cannot stimulate the neurotransmitter s receptors c By breaking it down reuptake with reabsorb some of the components d KEY to stop the activity within the synapse very quickly Synaptic gap cleft space between neurons the neurotransmitter goes across the gap very fast Post synaptic membrane extension from dendrite A Ionotropic receptor fast responding receptor 1 Responds directly to the ion and causes the ion channel to move 2 When the neurotransmitter binds it opens the ion channel 3 If the ion is sodium then the neurotransmitter that opens sodium channels it would be excitatory 4 If the ion is potassium and opens the channel potassium is going to leave the cell because there is more potassium on the inside than the outside making the charge inside more negative 5 Has less receptors than metabotropic receptors B Metabotropic receptors slow responding but lasts longer 1 Metabolic processes occurs within the cell membrane to open the ion channels 2 Linked to a G protein that travels to the channels from the inside causing it to open or it binds to an additional subunit that opens the channel C Post synaptic potentials polarity change within the cell body 1 Communication between neurons as neurotransmitters are released as they are connected to a receptor a Excitatory depolarizing EPSP if the neurotransmitter is excitatory then the action potential will likely occur needs more neurotransmitters in order to get the action potential to occur b Inhibitory IPSP potassium channels are opened as some neurotransmitters job is to mediate the activity by decreasing the responsiveness which hyperpolarizes and decreases the chances for an action potential IV Generation of action potential or hyperpolarization A Temporal Summation 1 If the sodium channels have reset the cell would fire without ever hyperpolarizing 2 The rapid depolarization could potentially reach the axon and reach the threshold B Spatial Summation 1 Spread out across space 2 They all occur at the same time the axon could get to the threshold 55 millivolt 3 Dendrite repolarizes and resets C EPSP and IPSP cancellation 1 If they fire at the same time they cancel out and it causes no change or shift in the membrane 2 All the processes happen constantly
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