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PSYC 1010
Jennifer Steeves

Chapter 3 What is your nervous system What are the two categories the cells in your nervous system fall into DescribeLiving tissue composed of cells The categories are glia and Neurons Nuerons are individual cells in the nervous system that receive and transmit information glia cells are part of the nervous system that help insulate and enhance conduction of messages across the axon they are present in the myelin sheathsCan a single drawing adequately represent a neuron How come What is this likeNo because they vary so much in terms of shapes and sizes it is like trying to draw a treeDescribe the different components of a nerve cellSoma the cell body of the neuron and it contains the nucleusDendrites are the parts of the neuron that are specialize to receive information Dendrites are usually great in numbers because a single neuron can receive signals from many other cellsAxon its a long thin fibre in which the neurons signal is transmitted from one neuron to another they can be very longMyelin sheath its the insulating material derived from glial cells and encases axons Myelin sheath speed up the signals that move along the axon if the myelin sheath deteriorates signals may not be transmitted effectively Detriment of myelin sheath is a major cause of multiple sclerosis which Is loss of muscle controleTerminal buttons they are small knobs that secrete chemicals called neurotransmitters which act as messengers which activate neighbouring neurons Terminal buttons usually branch off of one axon into several branches and attatch to a region of the dendrite close to each otherSynapse its the space where signals are transferred from one neuron to another Glia they are cells found throughout the nervous system and provide various types of support for neurons They are smaller than neurons but outnumber them 101 They also account for over 50 of the brains volume They supply nourishment to neurons and remove neurons waste products and provide insulation around many axonsIs the cell membrane semi permeable What does this lead to a buildup of What is this known as What does it make the neuron like Describe neuron resting potentialYes It leads to a buildup of a negative charge inside the neuron which is known as a charge This makes a neuron like a small battery Resting potential of a neuron is a neurons stable negative charge when the cell is inactiveWhat happens when the neuron is stimulated What happens if the voltage of a neuron remains constant What is an action potential What does the firing of an action potential causeWhen a neuron is stimulated neuron becomes less negatively charged and an action potential happens If voltage is constant neuron remains in resting potential Action potential is a very brief shift in a neurons charge that travels along an axon The firing of an action potential cause a change in voltage to rush down the axonAbsolute refractory period its the length of time in which the neuron cannot encounter an action potential after its action potential has already occurred This usually lasts about 12 millisecondsWhat is the all or nothing law for neurons Are action potentials all the same size Do weaker stimuli produce smaller action potentialsEither the neuron fires or it doesnt yes NoCan neurons convey information on the strength of the stimulus How do they do so What will a stronger stimulus causeYes by varying the rate at which they fire the action potentials in general a strong stimulus will cause a cell to fire more rapid volley of neural impulses than a weaker stimulus willWhats the difference between thinner and thicker axons How long does transmission of a charge take in a neuronThicker axons transmit neural impulses more rapidly than thinner ones do and transmission takes a few thousandths of a secondDo neurons every touch each other Describe a synaptic cleftNo and a synaptic cleft is the microscopic gap between the terminal button of one neuron and the cell membrane of another neuron Signals have to cross this gap to communicateWhat does the arrival of an action potential at the presynaptic neurons terminal buttons trigger the release of What are they Where are they stored When are they released What do they do after leaving the terminal button Whats special about terminal buttonsIt triggers the release of neurotransmitters which are chemicals thattransmit information from one neuron to anotherthey are stored in synaptic vesicles and they are released when a vesicle fuses with the membrane of the presynaptic cell and its contents are spilled into the synaptic cleft after theyre released neurotransmitters go across the synaptic cleft to the membrane of recipient cells postsynaptic neuron and
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