Biology of Behavior

Biology of Behavior - Chapter 3 The Biological Basis of...

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Unformatted text preview: Chapter 3 The Biological Basis of Behavior Communication in the Nervous System • Hardware: – Glia – structural support and insulation – Neurons – communication Structure of the Brain (cont.) • 3 functions of glial cells – Guide growth – Insulation – Chemically modulate neuron’s growth and function Structure of the Brain (cont.) • Neuron – A brain cell with 2 specialized extensions – Soma – cell body – Dendrites – receive – Axon – transmit away Figur e 3.1 Structure of the neuron. Neurons are the communication links of the nervous system. This diagram highlights the key parts of a neuron, including specialized receptor areas (dendrites), the cell body (soma), the fiber along which impulses are transmitted (axon), and the junctions across which chemical messengers carry signals to other neurons (synapses). Neurons vary considerably in size and shape and are usually densely interconnected. Neural Communication • Myelin sheath – speeds up transmission • Synapse – point at which neurons interconnect • Terminal Buttons – end of axon; secrete neurotransmitters • Neurotransmitters – chemical messengers The Neural Impulse • Hodgkin & Huxley (1952)- giant squid – Fluids inside and outside neuron • Electrically charged particles (ions) – Neuron at rest – negative charge on inside compared to outside »-70 millivolts – resting potential The Action Potential • Stimulation causes cell membrane to open briefly – Positively charged ions rush in • Shift in electrical charge travels along neuron • The Action Potential • Absolute Refractory Period • All-or-none law Action Potential • Reversal in electrical charge of an axon Figur e 3.2 The neural impulse. The electrochemical properties of the neuron allow it to transmit signals. The electric charge of a neuron can be measured with a pair of electrodes connected to a device called an oscilloscope, as Hodgkin and Huxley showed with a squid axon. Because of its exceptionally thick axons, the squid has frequently been used by scientists studying the neural impulse. (a) At rest, the neuron is like a tiny wet battery with a resting potential of about –70 millivolts. (b) When a neuron is stimulated, a brief jump in its electric potential occurs, resulting in a spike on the oscilloscope recording of the neuron’s electrical activity. This change in voltage, called an action potential, travels along the axon like a spark traveling along a trail Ion Channels and Transporters Ion channels and ion transporters regulate the number of ions inside and outside the axon Sending Signals: Chemicals as...
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This note was uploaded on 05/15/2011 for the course PSY 101 taught by Professor Wormer during the Fall '08 term at Grand Valley State.

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Biology of Behavior - Chapter 3 The Biological Basis of...

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