Chapter 12.1: General Functions, Organization, Nerves and Ganglia

General functions

• communication and control system

• collect information (sensory input): receptors detect stimuli and send sensory signals to spinal cord (sc) and brain

• process and evaluate information (integration): brain and sc determine response to sensory input

• initiate response to information (motor output): brain and sc send motor output via nerves to effectors (muscles or glands)

Structural organization

• central: brain and spinal cord

• peripheral: nerves and ganglia

Functional organization: sensory nervous system

• sensory nervous system: afferent nervous system, receives sensory info from receptors, transmits to CNS

  • somatic motor system: detects stimuli consciously perceives

  • visceral sensory: stimuli not consciously perceived (heart, kidneys)

Functional organization: motor nervous system

• motor nervous system: efferent nervous system, initiates motor output and transmits from CNS to effectors

  • somatic motor: send signlas to skeletal muscles

  • autonomic motor (visceral): involuntary commands to heart, smooth muscle and glands

    • sympathetic and parasympathetic divisions

Nerve

• bundle of parallel axons in PNS, connective tissue wrappings similar to muscle

• very vascular

• epineurium: encloses entire nerve, thick layer of DICT

• perineurium: wraps fascicle (bundle of axonz), DICT

• endoneurium: wraps individal axon, layer areolar CT, separates/electrically insulates axon

Structural classification

• cranial nerves: extend from brain

• spinal nerves: extend from spinal cord

Functional classification of nerves

• sensory nerves: sensory neurons signals to CNS

• motor neurons: motor neurons sending signals from CNS

• mixed nerves: both sensory and motor neurons

  • most nerves

  • individual nerves transmit only one type of info

• ganglion: cluster neuron cell bodies in PNS