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Chapter 3

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PSYC 1010
Myriam Mongrain

Chapter 3 September 22, 11 • Nervous system- signals are always being transmitted, received and integrates. It handles the information of my body. It is tissue that is made ip of cells. • 2 cells: 1. Neurons individual cells in the nervous system that receive, integrate and transmit information  make communication within the nervous system and also may send messages from the nervous system to muscles • soma/ cell body has nucleus and the chemical machinery o dendrites- are branches of the neuron. They receive all the information which then go into the soma. o Axon- after the information has gone in through the dentrites to the soma it then leaves the soma to go to other neurons, glans or muscles.  Can branch off to communicate with other cells.  Myelin speeds up the transmission of signlas that move along axons. o Terminal buttons- this is where the axon ends and it secretes chemicals called neurotransmitters. These chemicals are messangers that activate near neurons. o Synapses- when neurons exchange information with each other. • Summary: info is received at dendrites. Then passted through soma and alon the axon, which is then transmitted to dendrites of other cells at the synapses. 2. Glia are around the nervous system and give support for neurons. • Give nourishment, remove waste for neurons and give insulation for neurons to axons. o Myelin sheaths are from glia cells. o Play a role in development of nervous system in the embryo. o Can signal to other glia cells • Neural impulse- electrochemical reaction. On this inside and outside it has charged atoms called ions. o Difference in flow rates results to higher concentraton of negative ions inside the cell. o This voltage means that the neuron is a store of potential energy. o Resting potentioal neuron is stable, negative 1 charge when the cell isn’t active. • Constant voltage of neuron- cell is quiet. • When its stimulated- channels in cell membrane open allowing positively charged sodium ions to come in. • Action potential shift in neurons electrical charge that travels along an axon. • Voltage change goes down the axon • Absolute refractory its after action potential and hits is when the cell membrane is closed up and its “resting” only for a very short amount of time. • After this is the relative refractory period the neuron can fire and this one is very intense. • Neuron either fires or it doesn’t, and action potentials are all the same size. • Stronger stimulus will get a more rapid volley of neural impulses. • Thicker axons transmit impulses more rapidly. • Neural impulse is a signal, which is transmitted from neurons to other cells. • Synaptic cleft- a gap between neurons. In order for signals to communicate it has to pass this gap. When the action potential is at the acons it triggers the release of neurotransmitters, which are chemical that transmit information from different neurons. • Chemicals stores in synaptic vesicles. • Vesicle and membrane fuse together- neurotransmitters are released. They then diffuse across the synaptic cleft of receiving membrane. And here they can bind with other molecules in receptor sites. • Postsynaptic potentials range in size which increases or decreases the probability of neural impulses. • Messaging from cell to cell: 1. Excitatory positive voltage shift that increases the chances that postsynaptic neuron will fire action potentials. 2. Inhibitory does the opposite. • Reuptake- gets synapses to recycle materials. • Neuron has to integrate all the messages it sends and receives before it desides to send a neural impulse. If the right amount of PSPs happen the electrical currents add up which causes the cells voltage to reach the threshold and finally the action potential can be fired. o If too many inhibitory PSPs happn it will not allow excitatory PSPs. 2  State of neuron is the blacance between excitatory and inhibitory influences. • The stuff that goes in inside our minds depends on patterns of neural activity in neural networks. • Neurons are linked in complex networks or cell assemblies which influence our behavior. • When one neuron stimulates another neuron again and again this changes the synapses- learning has occurred. • Certain neurotransmitters work at certain synapses. o Transmitter has to go into a specific receptor sight for binding. Therefore, specific transmitters deliver signals to certain locations on the cell membrane. • Acetylcholine- only transmitter between motor neurons and voluntary muscles. o Determines attention, arousal and memory (if don’t have a lot of this can result to Alzheimer’s) • Is influenced by other chems in brain. o Smoke because of nicotine stimulates the ACH. (it pretends to be ACH which means it goes into the receptor sites causing PSPs.  agonist- mimics action of neurotransmitter. o Antagonist- chem that opposed action of neurotransmitter. • Monoaminrd: o Dopamine- neuorns control voluntary movements. o Norepinephrine- if don’t have enough of this you become depressed. o Serotonin- releasing neurons help with regular sleep and eating. • GABA (gamma aminobutyric) and glycine- only produce inhibitory PSPs • Have inhibitory effects at virtually all synapses. o GABA responsible for inhibition in the central nervous system.  Also adds to anxiety. • Glutamate- excitatory effects, helps memory and learning. • Nervous system internally produces morphine- like substances because of how the morphine binds to the specialized receptors in the brain. o Endorphins internally made chems that are like opiates (drug like morphine) in structure and effects.  These are all over the body and they help with pain. • Serotine and Dopamine (transmitters) are being found that they are related to behavior. • Peripheral nervous system it is made up of all the nerves and 3 nerve fibers. Its right outside the central nervous system. • Somatic nervous systemnerves that are connected to the voluntary skeletal muscles and sensory muscles. o Carry information from receptors to the CNS which then send messages to the muscles.  Afferent nerve fibers- info TO the CNS from the periphery of body.  Efferent nerve fibers- info from CNS to the periphery of body. • Automatic nerves system (ANS) nerves that connect to heart, blood vessels, muscles and glands. Controls automatic, involuntary and visceral functions, which people don’t usually think about. o Psychological part of emotions. o 2 sub divisions:  Sympathetic division- mobilized the body’s resources for emergencies, makes a fight- or- fight response.  Parasympathetic d
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