Lecture Notes--How Neurons function

Lecture Notes--How Neurons function - How Neurons function...

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How Neurons function Overview Neurons are nerve cells that transfer information within the body. Communication by neurons is based on two distinct types of signals: long-distance electrical signals and short-distance chemical signals. o The specialized structure of neurons allows them to use pulses of electrical current to receive, transmit, and regulate the long-distance flow of information within the body. o To transfer information between cells, neurons use a chemical signal that acts over very short distances. Neurons transmit sensory information, control heart rate, coordinate hand and eye movements, record memories, and generate dreams. Information is transmitted within neurons as an electrical current, consisting of the movement of charged ions. The connections made by a neuron specify what information is transmitted. Interpreting signals in the nervous system involves sorting a complex set of neuronal paths and connections. In more complex animals, this higher-order processing is carried out in groups of neurons organized into a brain or into simpler clusters called ganglia . Neuron organization and structure reflect function in information transfer. Networks of neurons with intricate connections form nervous systems. The neuron is the structural and functional unit of the nervous system. Most of a neuron’s organelles, including its nucleus, are located in the cell body . Two types of extensions arise from the cell body: numerous dendrites and a single axon. o Dendrites are highly branched extensions that receive signals from other neurons. o The axon is a longer extension that transmits signals to neurons or effector cells. o The axon joins the cell body at the axon hillock , where signals that travel down the axon are generated. Each branched end of an axon transmits information to another cell at a junction called a synapse. o Each axon branch ends in a synaptic terminal . At most synapses, information is passed from the transmitting neuron (the presynaptic cell ) to the receiving cell (the postsynaptic cell ) by means of chemical messengers called neurotransmitters . o The postsynaptic cell may be a neuron, muscle, or gland cell.
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o Depending on the number of synapses a neuron has with other cells, its shape can vary from simple to quite complex. Ion pumps and ion channels maintain the resting potential of a neuron. All cells have a voltage (difference in electrical charge) across their plasma membrane; this voltage is called the membrane potential . In neurons, inputs from other neurons or specific stimuli cause changes in this membrane potential, which act as signals to transmit and process information. The membrane potential of a neuron that is not transmitting signals is called the
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This note was uploaded on 11/14/2011 for the course BSC 2010 taught by Professor Pf during the Spring '08 term at FSU.

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Lecture Notes--How Neurons function - How Neurons function...

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