Lec.3 - Biology and Behavior Everything psychological is...

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Unformatted text preview: Biology and Behavior Everything psychological is ultimately and simultaneously biological The Nervous System Central Nervous System Basics Electrochemical system neuron is the basic building block All animals have neurons Neurons structure and to some degree function are the same Neurons basic building block of ns nerve cells found in the central nervous system brain and spinal cord brain has about 100 million nerve cells and weighs about 3 lbs. (on average 2% of your body weight) A Motor Neuron Neuron Response Excitatory when stimulated the neuron releases its stored neurotransmitters Inhibitory when stimulated the neuron becomes less likely to release its stored neurotransmitters (changes threshold) Cell body integrates graded potentials (inputs) decides what to do with the messages. Contains cell DNA determines which neurotransmitter this neuron produces determines which neurotransmitters excite and inhibit it Feeds this cell Axon Branch of neuron that Carry electrical current (when the threshold of excitation is reached) can be very long Some axons are covered with a MYELIN SHEATH End in axon bulbs (aka presynaptic terminals, terminal bulbs) Myelinated Axons If the human brain did not contain myelinated axons it would have to be 10 times bigger than it is to maintain the same velocity of nerve impulses. It makes you wonder about ET! A resting neuron difference between outside and inside of neuron produces a slight electrical charge -70 millivolts charge referred to as a polarized neuron has stored neurotransmitters to release Outside of neuron Mostly Sodium ions + large protein ions (slight -) Inside of neuron Mostly Chloride ions (-) Potassium Resting (polarized)Neurons have more positive ions on the outside and more negative ions on the inside Difference between outside and inside gives neuron its electrical charge Firing of a neuron action potential neural impulse is all-or-none causes the depolarization of the cell THIS IS THE ELECTRICAL PART! Neurotransmitters produced in this cell are released into the synapse Synapse Space between neurons neurons do not form connective tissue between each other Refractory Periods Absolute refractory period neuron cannot fire no difference in electrical ions inside and outside of cell Relative refractory period can fire, but neurotransmitters released will be less than if full resting potential is reached Firing of a Neuron Absolute Refractory Period Relative Refractory Period Time-70mV-40mV Resting 0mV Resting How Neurons Communicate Step by Step -- Neural Firing 1st Dendrites of resting neuron receive stimulation from neurotransmitters in synapse 2nd Soma determines excitatory vs inhibitory response 3rd - if excitatory, when neuron threshold is reached cell depolarizes 4th - action potential released down axon 5th - stored neurotransmitters are released from...
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Lec.3 - Biology and Behavior Everything psychological is...

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