TORTORA NERVOUS

• What is the main objective of both the nervous and endocrine systems?

  To keep controlled conditions within limits that maintain life
• How does the nervous system regulate body activities?

  By responding rapidly using nerve impulses
• What does Chapter 18 compare regarding the nervous and endocrine systems?

  The roles of both systems in maintaining homeostasis
• What are the responsibilities of the nervous system?

  Perceptions, behaviors, memories, and initiating voluntary movements
• What is the focus of this chapter on the nervous system?

  The organization of the nervous system and the properties of neurons and neuroglia
• What are neurons?

  Nerve cells that transmit impulses
• What are neuroglia?

  Cells that support the activities of neurons
• What does the autonomic nervous system do?

  Operates without voluntary control
• What are the two main branches of the autonomic nervous system?

  The sympathetic nervous system and the parasympathetic nervous system
• What is the role of the sympathetic nervous system?

  To increase heart rate and support emergency actions
• What is the role of the parasympathetic nervous system?

  To take care of "rest-and-digest" activities
• What is the enteric nervous system (ENS)?


  An extensive network of neurons in the gastrointestinal tract
• How does the ENS function in relation to the other branches of the ANS?

  It can function independently but communicates with and is regulated by the other branches
• What are the three basic functions of the nervous system?

  • Sensory function: Detects internal and external stimuli
  • Integrative function: Processes sensory information and makes decisions
  • Motor function: Elicits appropriate responses by activating effectors
• What is the sensory function of the nervous system?

  Sensory receptors detect internal and external stimuli
• What is the integrative function of the nervous system?

  It processes sensory information and makes decisions for responses
• What is the motor function of the nervous system?

  It activates effectors to elicit appropriate responses
• How does the nervous system demonstrate its functions when answering a cell phone?

  It detects the ringing (sensory), processes the decision to answer (integrative), and activates muscles to grab the phone (motor)
• What is the mass of the nervous system?

  About 2 kg (4.5 lb)
• What are the two main subdivisions of the nervous system?

  The central nervous system (CNS) and the peripheral nervous system (PNS)
• What does the central nervous system consist of?

  The brain and spinal cord
• What is the role of the CNS?

  To process incoming sensory information and generate thoughts, emotions, and memories
• What does the peripheral nervous system consist of?

  All nervous tissue outside the CNS
• What is a nerve?

  A bundle of hundreds to thousands of axons plus associated connective tissue and blood vessels
• How many pairs of cranial nerves emerge from the brain?

  Twelve pairs
• How many pairs of spinal nerves emerge from the spinal cord?

  Thirty-one pairs
• What is the function of sensory receptors?

  To monitor changes in the external or internal environment
• What does the sensory division of the PNS do?

  Conveys input into the CNS from sensory receptors
• What types of sensations does the sensory division provide information about?

  Somatic senses and special senses
• What are the basic parts of a neuron?

  A cell body, dendrites, and an axon
• What is the function of the cell body of a neuron?

  Contains the nucleus and organelles necessary for the neuron's function
• What are Nissl bodies?

  Clusters of rough endoplasmic reticulum in the neuronal cell body
• What is the role of the cytoskeleton in a neuron?

  Provides shape and support to the cell
• What is lipofuscin?

  A pigment that accumulates in aging neurons
• What is a ganglion?

  A collection of neuron cell bodies outside the CNS
• What is a nerve fiber?

  Any neuronal process that emerges from the cell body of a neuron
• What are dendrites?

  Receiving or input portions of a neuron
• What is the axon of a neuron?

  A long, thin projection that propagates nerve impulses
• What is the axon hillock?

  The cone-shaped elevation where the axon joins the cell body
• What is the trigger zone of a neuron?

  The area where nerve impulses arise at the junction of the axon hillock and initial segment