NERVOUS SYSTEM

• What is more complex than the most powerful computers?

  The circuits in the brain
• How can functional magnetic resonance imaging (MRI) be used?

  To construct a 3-D map of brain activity
• How is the vertebrate brain organized?

  Into regions with different functions
• What do nervous systems consist of?

  Circuits of neurons and supporting cells
• What type of nervous system do cnidarians have?

  A nerve net
• What is a nerve net?

  A series of interconnected nerve cells
• How are nerves defined in more complex animals?

  Bundles of axons from multiple nerve cells
• How do sea stars' nervous systems function?

  They have a nerve net in each arm
• What is cephalization?

  The clustering of sensory organs at the front
• What do relatively simple cephalized animals possess?

  A central nervous system (CNS)
• What does the CNS consist of?

  A brain and longitudinal nerve cords
• What is the nervous system organization in various animals?

  • Cnidarians: Nerve net
  • Sea stars: Nerve net with radial nerves
  • Bilaterally symmetrical animals: Cephalization
  • Flatworms: Central nervous system
  • Annelids and arthropods: Segmentally arranged ganglia
• What do annelids and arthropods have?

  Segmentally arranged clusters of neurons called ganglia
• How does nervous system organization correlate with lifestyle?

  Simple systems for sessile molluscs, complex for others
• What is the composition of the CNS in vertebrates?

  Brain and spinal cord
• What is the difference in nerve cord location between invertebrates and vertebrates?

  Invertebrates have a ventral nerve cord
• From what does the spinal cord and brain develop?

  The embryonic nerve cord
• What fills the central canal of the spinal cord?

  Cerebrospinal fluid
• What is the function of cerebrospinal fluid?

  To cushion the brain and spinal cord
• What does gray matter consist of?

  Neuron cell bodies, dendrites, unmyelinated axons
• What does white matter consist of?

  Bundles of myelinated axons
• What are the functions of glia in the CNS?

  • Ependymal cells: Circulate cerebrospinal fluid
  • Microglia: Protect from microorganisms
  • Oligodendrocytes and Schwann cells: Form myelin sheaths
  • Astrocytes: Support neurons and regulate environment
  • Radial glia: Aid in embryonic development
• What does the PNS do?

  Transmits information to and from the CNS
• What are the two types of neurons in the PNS?

  Afferent and efferent neurons
• Where do cranial nerves originate?

  In the brain
• Where do spinal nerves originate?

  In the spinal cord
• What are the components of the autonomic nervous system?

  • Sympathetic division: "Fight-or-flight" response
  • Parasympathetic division: "Rest and digest" response
  • Enteric division: Controls digestive tract
• What are the effects of the sympathetic division on target organs?

  Stimulates glucose release and accelerates heart
• What are the effects of the parasympathetic division on target organs?

  Stimulates salivary gland secretion and slows heart
• What are the three embryonic regions from which vertebrate brains develop?

  • Forebrain
  • Midbrain
  • Hindbrain
• How many brain regions form from the three embryonic regions by the fifth week of human development?

  Five brain regions
• What are the five brain regions formed from the embryonic regions?

  • Telencephalon
  • Diencephalon
  • Mesencephalon
  • Metencephalon
  • Myelencephalon
• What does the pancreas stimulate?

  Insulin production
• What does the adrenal medulla stimulate?

  Fight or flight response
• What does the inhibition of bladder emptying indicate?

  It prevents urination
• What is promoted during ejaculation?

  Vaginal contractions
• What effect does stimulation have on the pupil of the eye?

  Constricts the pupil
• What does stimulation of salivary gland secretion lead to?

  Increased saliva production
• What happens to bronchi in the lungs when they are constricted?

  Airflow is reduced
• What is the effect of slowing the heart?

  Reduces heart rate