Chapter 13

• Nervous system


  Coordinates and controls body activity. Its three basic responses are sensory (to detect and process external and internal stimuli), integrative (process sensory information), and motor (muscle contraction or glandular secretion).
• Central nervous system, CNS


  Portion of the nervous system that consists of the brain and spinal cord
• Peripheral nervous system, PNS


  Portion of the nervous system and consists of the cranial and spinal nerves, autonomic nervous system, and ganglia
• Neuron


  The basic unit of the nervous system
• Sensory neurons, afferent tracts, or ascending tracts


  Nerves that carry sensory impulses to the CNS. Here, sensory information like sound and light is converted into electrical impulses so the nerves can transport it.
• Associative neurons or connecting neurons


  Nerves that carry impulses from one neuron to another
• Motor neurons, efferent tracts, or descending tracts


  Nerves that carry impulses away from the CNS and to the muscles and glands.
• Soma


  The cell body that has the nucleus, and is responsible for maintaining the life of the neuron.
• Dendrites


  Root like structures that receive impulses and conduct them toward the cell body
• Dendr/o


  Dendrite
• Axon


  A single process that extends away from the cell body and conducts impulses away from the cell body
• Ax/o


  Axis or main stem
• Nerve fibers


  Dendrites and axons
• Nerves or nerve trunks


  Specialized tissues that bind together nerve fibers
• Neurolemma or neurilemma


  Tube like membrane that covers nerve fibers
• Nuclei


  Neuron cell bodies grouped together in the CNS
• Ganglia


  Neuron cell bodies grouped together outside the CNS.
• Synapse


  The junction between two neurons or between the neuron and the receptor
• Synaps/o and synapt/o


  Space or point of contact
• Neurotransmitter


  A chemical substance that whose release is triggered by neural impulses. It allows a signal to move from one neuron to another.
• Neuroglia or glial cells


  Supportive cells of the nervous system. They consist of astrocytes, microglia, oligodendrocytes, and Schwann cells.
• Gli/o


  Glue
• Astr/o


  Star
• Astrocytes


  Star shaped cells that cover the capillary surface of the brain and helps form the blood brain barrier in the CNS.
• Blood brain barrier, BBB


  Separates nervous tissue from the blood. Consists of capillary walls in the CNS without fenestrations and the surrounding astrocytes. It prevents the passage of drugs, chemicals, and some microbes from entering the CNS.
• Micro-


  Small
• Microglia


  Small phagocytic cells that help fight infection in the CNS
• Oligo-


  Few
• -cyte


  Cell
• Oligodendrocytes


  Cells with few branches that hold the nerve fibers together and help form the myelin in the CNS.
• Schwann cells


  Help form myelin in the PNS
• Myelin or myelin sheath


  The protective covering over some nerve cells, including parts of the spinal cord, white matter of the brain, and most peripheral nerves. Serves as an electrical insulator.
• Myelinated nerves


  Nerves surrounded by myelin. They transport a signal much faster than nonmyelinated nerves
• White matter


  Myelinated nerves
• Gray matter


  Nonmyelinated matter composed of cell bodies, branching dendrites, and neuroglia.
• Nodes of Ranvier


  Gaps in the myelin sheath. Ionic exchange takes place here.
• Nonmyelinated nerves


  Nerve fibers with a very thin layer of myelin. Some are located in the autonomic nervous system.
• Nerve


  One or more bundles of impulse carrying fibers that connect the CNS to other parts of the body
• Neur/i and neur/o


  Nerve or nerve tissue
• Tract


  A group of nerve fibers located in the CNS. Ascending ones carry impulses toward the brain and descending ones carry nerve impulses away from the brain.