Exam 1 Review What are the parts of a neuron Could you label those parts of a neurons Could you draw label a neuron There is a good chance you ll have to on your first exam soma dendrites axon axon terminal dendritic spines axon hillock myelin What is a synapse Terms presynaptic postsynaptic synaptic gap ie synaptic cleft where neurotransmitters are relayed from one neuron to another the terminal of a neuron comes really close to the dendritic spines of another neuron to release neurotransmitters there are lots of synapses on a neuron whether a cell fires an action potential depends on the balance of excitatory and inhibitory inputs the simplest form of a postsynaptic response is the opening of a single type of transmitter gated ion channel ligand gated What are the 3 main types of neurons multipolar in brain the pics we draw bipolar soma in middle unipolar soma is a process off of it in muscle What are the different types of glia oligodendrocytes produce myelin in CNS Schwann cells produce myelin in PNS Also Microglia Radial glia and astrocytes BBB In general what is different between glia and neurons How can you connect neurons What would be the functional significance of such connections 1 1 relay not common many 1 gain complexity ramps up the neuron good for detail 1 many arousal What is the difference between an inhibitory neuron and an excitatory neuron excitatory neurotransmitter excites the postsynaptic cell glutamate inhibitory neurotransmitter inhibits the postsynaptic cell GABA modulatory neurotransmitter excites or inhibits postsynaptic cell depends on receptor like dopamine What is a neurotransmitter Where does the action potential occur begins at axon hillock travels down axon to terminal for neurotransmitter to be released due to movement of ions lots of sodium and chloride outside of the cell lots of potassium inside the cell other negatively charged organic compounds inside the cell A resting potential of 70mV What ions are involved Understand the terms Polarization Depolarization Hyperpolarization depolarization when the neuron becomes less negative o sodium entering cell adds a positive charge to negative environment hyperpolarization when the neuron becomes more negative o chloride entering cell potassium leaving cell o cannot fire action potential when cell is hyperpolarized polarized just means different What forces act on the ions What is a voltage gated channel in the membrane of the axon opened by changes in the membrane potential for both Na and K Na ones are more sensitive K channels require a greater change in membrane potential before they open at 70mV sodium channels are closed potassium channels are mostly closed Starting w threshold being reached at the axon hillock what happens during an action potential ions flow in and out along a concentration gradient where they flow from high concentration to low concentration diffusion and an electrical gradient where ions flow to areas of opposite charge opposites attract when threshold is reached 50mV voltage gated sodium channels open up sodium rushes into cell cell becomes depolarized voltage gated potassium channels open up and voltage gated sodium channels close potassium rushes out of cell cell becomes hyperpolarized voltage gated potassium channels close and that part of the membrane is back at 70mV the sodium inside the cell diffuses to the next Node of Ranvier unmyelinated segment of axon between myelinated segments the membrane at that node is now 50mV VG sodium channels open sodium rushes in VG sodium channels close VG potassium channels open potassium rushes out sodium diffuses to next node What is the role of calcium when the action potential reaches the axon terminal it opens up voltage gated calcium channels calcium enters the terminal and allows synaptic vesicles full of neurotransmitters to bind to the terminal membrane and release the neurotransmitter into the synaptic cleft What is the function of myelin What are nodes of Ranvier and what do they have that myelinated segments of the axon do not have What is an IPSP EPSP What is the big difference b t an action potential and an EPSP post synaptic potentials inhibitory and excitatory synapses neurotransmitter is released from the terminal of the presynaptic cell neurotransmitter binds to receptor in membrane of postsynaptic cell ion channel opens receptor itself might be a channel or not called ligand gated ions go thru slightly depolarizing or hyperpolarizing the postsynaptic cell o Cl if inhibitory neurotransmitter o Na K or Ca2 if excitatory neurotransmitter Synaptic potential is a change in voltage graded EPSP or IPSP where action potentials are all or none action potential electrical impulses that provide basis for conduction of info EPSP depolarization in the postsynaptic cell can be various sizes What determines if threshold is reached at the axon hillock synaptic activity on the dendrites and soma if all of the input on that neuron from other neurons can reach 50mV there ll be an action potential whether cell fires depends on balance of E and I inputs sum of E and I must reach threshold at axon hillock What is the difference between voltage gated channels and ligand gated channels both in terms of their location and how they open voltage gated action potentials ligand gated synaptic potentials What are the 2 types of ligand gated channels How do they differ from one another receptors protein in the membrane that a neurotransmitter binds to ionotropic also channels neurotransmitter binds channel is opened ions pass through metabotropic receptors do not have channels neurotransmitter binds things are activated on the receptor inside the cell second messenger is used to open ion channels and or do other things inside the cell Why is inhibition an important part of nervous system physiology What is the rate law the strength of a stimulus is represented by the rate of firing of an axon the size of each acion potential is always constant the rate of firing is limited by the refractory period an intense stimulus leads to more action potentials per second What is the doctrine of specific nerve energies we are only aware of the activity in our nerves and we cannot be directly aware of the world itself From slide 24 what did each scientist contribute to our understanding of neurotransmission Von Hemholtz speed of signals in human sensory nerves by studying frog legs Ramon and Cajal neurons were their own units and synapses Sherrington
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