Bio 385 Chapter 3 summary

Chapter 3




Layout of Nervous System


 CNS
o Division of nervous system located within skull and spine
o Brain = skull
o Spinal cord = spine
 Peripheral NS
o Located outside skull and spine
o Somatic – interacts with external environment
 Composed of afferent nerves, carry sensory signals from skin, skeletal
muscles, joints, ears, eyes, etc.
o Automatic – regulates internal environment
 Afferent nerves carry signals from internal organs to CNS
 Efferent nerves that carry motor signals from CNS to internal organs
 Two kind of efferent nerves
 Sympathetic – project from the CNS in lumbar (small of back) and
thoracic (chest area) regions of spinal cord
 Parasympathetic – project from brain and sacral (lower back) to
spinal cord


Cells of the Nervous System


Anatomy of Neurons
 Neurons – cells responsible for reception, conduction, and transmission of
electrochemical signals
 External Features
o Cell membrane
o Dendrites
o Axon hillock
o Axon
o Nodes of Ranvier
o Buttons
o Synapses
o Cell body
o Myelin
 Internal features
o Endoplasmic reticulum
o Nucleus