The Brain and Behavior (Part 3)
The Brain and Behavior (Part 3) PSYC-11762-001
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This 5 page Class Notes was uploaded by Lauren Thompson on Tuesday February 9, 2016. The Class Notes belongs to PSYC-11762-001 at Kent State University taught by Robin L. Joynes in Summer 2015. Since its upload, it has received 33 views. For similar materials see General Psychology in Psychlogy at Kent State University.
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Date Created: 02/09/16
The Brain and Behavior (Part 3) Nerve cells and their messages The neuron o Specialized cell of the nervous system that is used to detect information, transmit information and affect muscles and glands These are found in the brain, spinal cord and nervous system They are a different shape than other cells because they are specialized to do three things Detect information Transmit that information Then, cause action or an output to muscles or glands o There are many different structure of a neuron The Dendrites These receive messages from neighboring neurons Also, sometimes receive messages from outside These look like tree branches Neurons can be dendrite "rich" These neurons have a lot of dendrites because they are located in an area where it is very important that every message that comes through is processed Neurons can also have very little dendrites These neurons are located in areas that do not receive a lot of messages so it is not as important that they contain a lot of dendrites Axon Conducts nerve impulses from the cell body to distant location What transmits messages This is where the electrical signal comes to play Myelin Sheath These increase the speed and efficiency of the nerve impulse Made up of lipids (fats) This serves as insulation and protection to protect the electrical signal that is traveling along the axon so it doesn’t lose its energy If an axon doesn’t have myelin sheaths speed of the electrical signal is much slower Terminal Buttons Release chemical messages (neurotransmitters) onto neighboring dendrites Each knob contains a chemical message The terminal buttons wait for an electrical signal to tell them to release the neurotransmitters onto other dendrites or muscles The Neural Impulse o The electrical message within a neuron Electrochemical Transmission o The communication from nerve cell to nerve cell Neurons conduct an electrical signal followed by a chemical signal followed by a electrical signal…and it keeps going Dendrites -> Soma -> Axon -> Terminal Button o How does a neuron generate electricity? Charged particles called Ions Sodium, potassium and Chloride When these are put in a solution they dissociate and conduct electricity They can generate electricity by using the membrane as a battery Differences in charges are measured by voltz The inside is more negative than the outside -70 mv is the normal range of the inside of the membrane The positive and the negatives line up right alone the membrane because they are attracted to each other o Membrane potential This is the difference in charge across the cell membrane There are holes or "gates" along the cell membrane where sodium can get in. When the cell is at rest the gates are closed When the axon is stimulated the gates open Stimulation occurs, sodium channels open and sodium comes rushing into neuron. Charge becomes more positive. Potassium starts leaving the cell and this starts making it more negative again This is called an action potential There is a spike of positivity then it falls back down This goes down the line until it reaches the terminal buttons Threshold This is the minimum amount of stimulation necessary to open channels and trigger the neural impulse Reminder Na+ goes in K+ moves out o Action Potential The brief wave of positive electric charge that sweeps down the axon Sodium is found inside and potassium is found outside like mentioned earlier Now the neuron needs to reset to get it to "work" again This is down through the sodium potassium pump This pump grabs sodium and "throws" it out of the cell and "sucks" potassium back in to reset the neuron for the next stimulation This pump kicks in immediately after the action potential takes place Refractory period This is the time being were after a neuron fires it cannot fire again because it is busy being reset through the sodium potassium pump All or none law If threshold is reached, a full action potential occurs. If threshold is not reached, then no action potential will occur Basically saying unless threshold is reached the neuron will not fire Neurons always fire in the exact same way Electrochemical Transmission o Otherwise known as chemical messages Communication from nerve cell to nerve cell o The chemical messages carry neurotransmitters that get released into the synaptic gap o What happens when the action potential reaches the terminal buttons at the end of the neuron? The terminal buttons eject neurotransmitters into the gap Synaptic Transmission o There are Synaptic Vesicles Store neurotransmitters The vesicles merge with the cell membrane and release the neurotransmitters into the synaptic gap o Neurotransmitters What carry the chemical messages These float across the space to bind with receptors o Receptors Receive the chemical messages otherwise known as neurotransmitters The receptors receive the transmitters and allow them to make an action occur and then they pop off and go to the next receptor or get removed from the synaptic gap These are very specific Example: Dopamine only fits in a dopamine receptor So, putting it all together o Dendrites receive a message and tell the cell body (soma) which tells the axon which makes an action potential occur until it reaches the terminal buttons which then release neurotransmitters…. Types of Synapses o Excitatory Synapse Neuron is more likely to produce an action potential A neuron fires, releases a neurotransmitter to another neuron which now produces a action potential o Inhibitory Synapse Neuron is less likely to produce an action potential A neuron fires a neurotransmitter to another neuron but this neurotransmitter makes neurons stop firing so it inhibitory o You need a balance of both of these types of synapses all the time How do you eliminate Neurotransmitters o You only want them to send their message one time Enzymatic degradation There are enzymes in the synapse that are specifically there to destroy the neurotransmitters after they have done their job Reuptake This is recycling of the neurotransmitters They get "sucked" back up into the terminal buttons to be reused at a later time Pictures: Myelin Sheath Stimulated: Open Nodes: This is where the gates open
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