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Unformatted text preview: CHAPTER THREE: The Biological Basis of Behaviour Nervous System- complex communication networks in which signals are constantly being transmitted, received and integrated- behaviour depends on rapid information processing The 2 types of Nervous System Cells are- Glia- glue; provide structural support, nourishment and insulation for neurons o involved in the removal of waste o helps maintain the chemical environment of the neurons- Neurons- the individual cells in the Nervous System that receive, integrate (put together) and transmit information o basic links that permit communication Soma- or cell body; contains the cell nucleus and much of the chemical machinery common to most cells- used for handling information Dendrites- the parts of a neuron that are specialized to receive information (branch-like) Axon- a long, thin fibre that transmits signals away from the soma, to other neurons or to muscles or glands- branch off to communicate with a number of other cells Myelin Sheath- an insulating material, derived from glial cells, that encases some axons- serves to speed up the transmission of signals that move along axons Terminal Buttons- located at the axon end; small knobs that secrete chemicals called neurotransmitters- neurotransmitters- serve as messengers that may activate neighbouring neurons; chemicals that transmit information from one neuron to another Synapses- a junction where information is transmitted from one neuron to another The General Pathway of Information (visual on pg 79 Fig.3.1)- dendrites receive information- information is passed to the soma- along the axon- transmitted to synapses of adjacent neurons - neurotransmitters are released to activate neuron (triggered by terminal button)- information is now in new neuron , and being passed to the dendrites (which are then connected to other axon new neuron) Neural Impulse- complex electrochemical reaction energy used to send information (pg 81 Fig.3.2)- positively charged on the outside (K + )- negatively charged on the inside (Na- )- they do not cross the membrane at the same time creates overall charge- neuron therefore, carries potential energy and acts as a tiny battery- resting potential- of a neuron is its stable, negative charge when the cell is inactive- when the neuron is stimulated, channels in its cell membrane open (sodium gates open) Action Potential- is a very brief shift in a neurons electrical charge that travels along the axon- created at the point when the neurons charge is less negative- firing action channels in the cell membrane that opened to let in sodium close up Absolute Refractory Period- the minimum length of time after an action potential during which another action potential cannot begin All-or-None Principle:- neuron fires or it doesnt- action potential is all the same size- weaker stimuli do not produce smaller action potentials- the stronger the stimulus, will cause the cell to fire more rapidly (rate) THE SYNAPSE: where neurons meet...
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- Spring '11