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Ch44outline - 44 Neurons and Nervous Systems 44.1 What...

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44 Neurons and Nervous Systems 44.1 What Cells Are Unique to the Nervous System? 44.2 How Do Neurons Generate and Conduct Signals? 44.3 How Do Neurons Communicate with Other Cells? 44.1 What Cells Are Unique to the Nervous System? Nervous systems have two categories of cells: _____________ generate and propagate electrical signals, ________________-. _____________ provide support and maintain extracellular environment. Neurons are organized into networks. __________ neurons carry information into the system. ___________ neurons convert input into action potentials. __________ neurons carry commands to effectors . _____________ store information and help with communication in the system. Networks vary in complexity. Nerve net: simple network of neurons. ____________ : neurons organized into clusters, sometimes in pairs. Brain : the largest pair of ganglia. ________________________ – consists of cells found in brain and spinal cord Peripheral nervous system (PNS) – neurons and support cells found outside the CNS Neurons pass information at synapses : The ______________ sends the message. The postsynaptic neuron receives the message. Most neurons have four regions: ___________ : contains the nucleus and organelles
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___________ : bring information to the cell body Axon : carries information away from the cell body Axon terminal : forms synapse at tip of axon Glial cells, or glia, outnumber neurons in the human brain. Glia do not transmit electrical signals but have several functions: Support during development Supply nutrients Maintain extracellular environment Insulate axons ______________________ produce myelin and insulate axons in the CNS. Schwann cells insulate axons in the PNS. __________- contribute to the blood–brain barrier, which protects the brain. 44.2 How Do Neurons Generate and Conduct Signals? Action potentials are the result of ions moving across the plasma membrane. Ions move according to differences in concentration gradients and electrical charge. ________________----- is the electric potential across the membrane. ___________________ is the membrane potential of a resting neuron. ______________ causes electric current as ions to move across cell membranes. Major ions in neurons: Sodium (Na + ) Calcium (Ca 2+ ) Membrane potentials are measured with electrodes.
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The resting potential of an axon is –60 to –70 millivolts (mV). The inside of the cell is negative at rest. An action potential allows positive ions to flow in
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This note was uploaded on 04/18/2008 for the course BIO 1306 taught by Professor Adair,tamarah during the Spring '08 term at Baylor.

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Ch44outline - 44 Neurons and Nervous Systems 44.1 What...

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