FINAL
45% essay questions
55% ch 12 and slide only for ch 13&14
Chapter 12
• Nervous Homeostasis
o Two Systems work together to maintain homeostasis—Nervous and Endocrine
o Nervous System has three functions
o Sensory-monitor changes internally and externally via sensory neurons
o Integrative-analyzes, stores, and makes decisions upon sensory data via associative
neurons
o Motor-respond to stimulus by initiating actions via motor neurons
• Divisions of Nervous System
o Central Nervous System (CNS) —Brain and the spinal cord
o Peripheral Nervous System (PNS) – cranial (12 pairs) and spinal (31 pairs) nerves
• Functional subdivisions
o Thalamus links these two
o Somatic nervous system
• Conscious
o Autonomic nervous system
o Unconscious
o Includes enteric nervous system (flowchart in pp)
• Nervous System Divisions
o CNS receives incoming sensory data, integrates and correlates data, thoughts and
emotions generated and memories are stored
o PNS is organized directionally primarily Sensory/Afferent neurons (into CNS) and
Motor/Efferent (away from CNS)
o Both CNS and PNS organized secondarily based on conscious control Somatic or
Voluntary (SNS) and Autonomic or Involuntary (ANS)
• ANS Divisions
o Sympathetic
• Survive the next 5 minutes
• “scared”
• thoracolumbar
o Parasympathetic
o Survive the next 5 days
o “normal”
o cranisacral
• Nervous Histology
o Nervous system contains two general types of cells—neurons and neuroglia
o Neurons are classified based upon number of processes extending from cell body—
multipolar, bipolar, and unipolar
o Neuroglia classification is based upon location (4 in CNS, 2 in PNS), anatomy and
function
• CNS Neuroglia
o Oligodendrocytes-round with few processes,
• Support, myelinate CNS neurons
o Astrocytes-star shaped, metabolize neuro-transmitters, K+ balance, blood/brain barrier
• Developmental migration of neurons
o Microglia-small cells with few processes, phagocytic cells derived from monocytes
o Migrate to site of injuries
o Ependymal cells-simple cuboidal to columnar
o Epithelium, line ventricles and central spinal
o Canal, produce and circulate cerebrospinal fluid
• PNS Neuroglia
o Schwann cells-flattened cells arranged around Axons in PNS, myelinate axons
o Satellite Cells-flattened cells associated with Soma and ganglia in PNS, support
• Electrical Signals in Neurons
o Neurons are electrically excitable due to the voltage difference across their membrane
o Communicate with 2 types of electric signals
• action potentials travel both long and short distances
• graded potentials are for short distances
o In living cells, a flow of ions is dynamically maintained across the cell membrane
• Four Types of Ion Channels
o Leakage Channels-randomly alternate open and closed, ions follow gradient, more K
o Voltage Gated Channels-open in response to changes in membrane potential
o Ligand Gated Channel-opens when receptor portion of channel binds ligand (ACh
muscle)
o Mechanically Gated Channel-opens in response to some physical stimulation
• Resting Membrane Potential
o Negative ions along inside of cell membrane & positive ions along outside
