Chapter 54

Summary		Questions		Media Resources
54.1 The nervous system consists of neurons and supporting cells.
• The nervous system is subdivided into the central nervous system (CNS) and peripheral nervous system (PNS).		1.  What are the differences and similarities among the three types of neurons?		•Neuroglial Cells • Myelin Sheath Formation
54.2 Nerve impulses are produced on the axon membrane.
• The resting axon has a membrane potential of -70 mV; the magnitude of this voltage is produced primarily by the distribution of K+. • A depolarization stimulus opens voltage-gated Na+ channels and then K+ channels, producing first the upward phase and then the repolarization phase of the action potential. • Action potentials are all or none and are conducted without decrease in amplitude because each action potential serves as the stimulus for the production of the next action potential along the axon.		2.  Which cation is most concentrated in the cytoplasm of a cell, and which is most concentrated in the extracellular fluid? How are these concentration differences maintained? 3.  What is a voltage-gated ion channel? 4.  What happens to the size of an action potential as it is propagated?		•Membrane Potential •Action Potential •Action Potential *Activities: •Action Potential 1 •Sodium-Potassium Pump •Action Potential 2 •Biologist 20 Meters Below •Sodium-Potassium Pump •Resting Membrane Potential •Saltatory Conduction
54.3 Neurons form junctions called synapses with other cells.
• The presynaptic axon releases neurotransmitter chemicals that diffuse across the synapse and stimulate the production of either a depolarization or a hyperpolarization in the postsynaptic membrane. • Depolarizations and hyperpolarization can summate in the dendrites and cell bodies of the postsynaptic neuron, allowing integration of information.		5.  If a nerve impulse can jump from node to node along a myelinated axon, why can't it jump from the presynaptic cell to the postsynaptic cell across a synaptic cleft?		•Synapse Structure •Nervous Tissue •Synapse • Smoking Ban •Neural Development in Moths •Is Smoking Addictive? •Nobel Prize 2000 •  Drug Addiction and Synapse
54.4 The central nervous system consists of the brain and spinal cord.
• The vertebrate brain is divided into a forebrain, midbrain, and hindbrain, and these are further subdivided into other brain regions. The cerebral cortex has a primary motor area and a primary somatosensory area, as well as areas devoted to the analysis of vision and hearing and the integration and association of information. • The spinal cord carries information to and from the brain and coordinates many reflex movements.		6.  Where are the basal ganglia located, and what is their function? 7.  How are short-term and long-term memory thought to differ in terms of their basic underlying mechanisms?		•Central Nervous System •Spinal Cord Anatomy A • Spinal Cord Anatomy B •Human Brain •Reflex Arc •Nervous System Introduction •Central Nervous System •Cerebrum II •Making Smarter Mice •Repetition and Learning •Learning Requires Sleep • Discovery of Site in Brain Linked to IQ •Primitive Fish Brains •Evolution of Vertebrate Brain •Brain Mass vs. Body Mass •Knee-Jerk Reflex
54.5 The peripheral nervous system consists of sensory and motor neurons.
• The sympathetic division is activated during fight-or-flight responses; the parasympathetic division opposes the action of the sympathetic division in most activities.		8.  How do the sympathetic and parasympathetic divisions differ in the locations of the ganglionic neurons?		•Peripheral Nervous System •Human Nervous System •Peripheral Nervous System •Autonomic Motor Reflex •Autonomic Nervous System Divisions

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