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Psyc 1001G.docx

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Carleton University
PSYC 1001
Kavita Prakash

th Psyc 1001G – Neurons/Nervous system – Jan 29 2013 - Neurons relay messages. Neurons – individual cells in the nervous system that receive and transmit information. - 1. Soma = cell body (nucleus) - 2. Dendrites = receive information from other neurons (“branches” of the cell) - 3. Axon = tube like structure, carries information from cell body to another neuron - 4. Myelin Sheath = it speeds up rate of transition, fatty substance on axon. In multiple sciroses the myelin sheath is damaged – have trouble with motor control - 5. Terminal Buttons = small knobs at end of axon that secretes neurotransmitters. - 6. Neurotransmitters = chemicals that provide messages - 7. Synapse (synaptic gap) = (Neurons do not touch) the synapses is the point at which neurons meet/”connect”. Glia Cells - Glue that holds everything together - Provide support - Smaller in size than neurons - 10:1 ratio compared to neurons - They remove waste (dead neurons) - They compose the myelin sheath (fatty layer on the axon) - Development of Nervous System in embryo (in the 2 trimester – glia plays hug role in brain and nervous system of the child) - Linked to Alzheimer’s disease The Neural Impulse - The electrochemical reaction that moves through the neuron o You can measure this - Ions o Positive (Sodium and Potassium) and negative (Chloride) charges - Neuron has a lot of negative within the membrane – there is a gradient between the system and environment - Resting state = stable, negatively charges of -70 millivolts when at rest (Resting potential) o More negative in the inside when in this state Activation Potential - Stimulation causes cell membrane to open briefly o Different neurons used for different funtions (touch, taste smell ect) - Cell membrane in this case opens up o Chandelles state to open. o Cell becomes more positive in the inside + o K o goes in, Na goes out - Depolarization - Positively charged sodium ions flow in Sift in electrical charge travels along neuron - The Action potential – Shift in neurons electrical charge - All or None Law – Neuron fires or it doesn’t - Refractory Period – no action potential can occur (very short amount of time) The Synapse - Point at which neural impulse travels from one neuron to another - Point of communication between neurons - There is the pre and post - Synaptic Cleft = microscopic gap - Presynaptic neuron = sending signal down axon - Postsynaptic neuron = receiving signal at dendrite When a Neurotransmitter binds: The Postsynaptic Potential - Voltage charge at receptor site – Postsynaptic potential (PSP) - Excitatory PSP = stimulating firing of neuron - Inhibitory PSP = stops the neuron form firing Neurotransmitters - Specific neurotransmitters work at specific synapses (they will work on certain locations) o Lock and Key mechanism – It has to be a perfect fit. In depression there might be to much or too little of a neurotransmitter. Drug that mimic neurotransmitters (such as dopamine) wi Video notes - CNS (nerve pathways) - The brain – cerebral cortex (two parts)  Sensory cortex and motor cortex (pain)  Hippocampus - connects the two sides of the brain  Reward pathway activated by drugs (pleasurable feelings) o Axons ends at a terminal o Exocytosis – secretion of neurotransmitters into the membrane of the dendrite nodes o Receptors sodium ions enter the cell when the neurotransmitters attach to the receptor and open channels o Acetylcholin…. destroys acytle coline. o Dopamine is produced by G –protein –AMP?? o Dopamine is not destroyed – taken up by uptake pumps (proteins), packed in vesicles and reused Drugs and the Brain - Drugs come from plats mainly - In tobacco – nicotine: goes from smoke –> lungs –> blood stream –> brain. o Nicotine competes with acytyl coline and wins – large current is produced across the neurons – Caudate nucleus is affected (involuntary movements occur – tremors) - Coca plant – cocaine : blood vesicles – heart – brain. o Diffuses easily into the brain from the blood stream. It works on dopamine  g protein  AMP. Cocaine binds here and prevents the function of the uptake pumps making them stop functioning. In result the dopamine is more present in synapse; reacts with its receptors causing over stimulation of the neurons. Individuals can suffer from cocaine censures where they suffer from irregular heartbeats which lead to fatal results. …. Neurotransmitters contin
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