Nervous Tissue

• What is the primary function of the nervous system?

  To detect and respond to changes inside and outside of the body through electrical impulses
• What are the two main divisions of the nervous system?

  The central nervous system (CNS) and the peripheral nervous system (PNS)
• What are the two types of neurons in the peripheral nervous system?

  • Motor neurons (efferent): transmit impulses from the CNS
  • Sensory neurons (afferent): transmit impulses to the CNS
• What are the two subdivisions of the peripheral nervous system?

  • Somatic Nervous System: controls voluntary movements via skeletal muscles
  • Autonomic Nervous System: controls involuntary movements via smooth muscles
• What is the role of the sympathetic nervous system?

  It mobilizes the body for "fight or flight" responses
• What is the role of the parasympathetic nervous system?

  It conserves energy and manages "rest and digest" functions
• What type of neurons transmit impulses to the CNS?

  Sensory (afferent) neurons
• What type of neurons transmit impulses from the CNS?

  Motor (efferent) neurons
• What are the two types of nervous tissue?

  • Neurons: basic working units that generate and transmit nerve impulses
  • Neuroglia: support neurons and are formed from glial cells
• What are the main components of a neuron?

  • Dendrites
  • Cell body (nucleus)
  • Axon hillock
  • Axolemma
  • Axon
  • Neurilemma
  • Terminal buttons
• What is the difference between myelinated and unmyelinated neurons?

  Myelinated neurons have a myelin sheath, while unmyelinated neurons do not
• What is the function of the myelin sheath?

  To insulate the axon and increase the speed of nerve impulse transmission
• What are nodes of Ranvier?

  Gaps in the myelin sheath along the axon
• What are terminal buttons in a neuron?

  Structures at the end of an axon that release neurotransmitters
• What is the role of neuroglia in the nervous system?

  To support and protect neurons
• How do the functions of the somatic and autonomic nervous systems differ?

  The somatic nervous system controls voluntary movements, while the autonomic nervous system controls involuntary movements
• What are the electrical impulses called that neurons transmit?

  Action potentials
• How is the initial strength of the action potential maintained?

  It is maintained throughout the length of the neuron
• What roles do neurons play in action potentials?

  Some initiate action potentials, while others act as relay stations
• What types of stimuli can initiate action potentials?

  Stimuli from outside the body, like touch, and inside the body, like changes in CO2 concentration
• What forms grey matter in the nervous system?

  Nerve cell bodies
• Where is grey matter found in the nervous system?

  In the periphery of the brain and the center of the spinal cord
• What forms white matter in the nervous system?

  Axons and dendrites
• Where is white matter located in the nervous system?

  Deep in the brain
• What is myelin?

  A fatty substance that forms around the axon
• How does myelin affect transmission speed?

  It speeds up transmission alongside the Nodes of Ranvier
• What happens when several axons are embedded in one large Schwann cell?

  There is no exposed axon membrane, resulting in slower action potentials
• How many neurons are involved in the transmission of an impulse?

  There is always more than one neuron involved
• What is the synapse?

  The point at which the presynaptic neuron passes the action potential to the postsynaptic neuron
• What are terminal boutons?

  Small branches with swellings at the free end of the presynaptic neuron
• What is the synaptic cleft?

  The space between the terminal boutons and the dendrites of the postsynaptic neuron
• What do terminal boutons release?

  A neurotransmitter
• Where are neurotransmitters created and stored?

  They are created in the cell bodies and stored in synaptic vesicles inside the terminal boutons
• How do neurotransmitters function across the synaptic cleft?

  They diffuse across the synaptic cleft and are usually short-lived
• How are neurotransmitters inactivated?

  By enzymes in the postsynaptic neuron
• What happens to inactivated neurotransmitters?

  They are taken back to the terminal boutons