Anatomy and Physiology: The Nervous System

Nervous System Structure and Function

Nervous system

The nervous system serves as the chief coordinating agency. Conditions within and outside the body are constantly changing; the nervous system responds to these changes causing the body to adapt itself to new conditions so that balance is maintained.

Organisation of the nervous system:

Structural divisions:

• Central Nervous system
  • Includes the Brain and Spinal Cord
    • Spinal cord functions
      • Conduction of sensory impulses to the brain
      • Conduction of motor impulses from the brain
      • Reflex response activities

• Peripheral Nervous System
  • Includes cranial nerves which carry impulses to and from the brain and spinal nerves which carry impulses to and from the spine

Functional divisions:

• Somatic (voluntary) nervous system
  • Function – supplies skeletal muscle
• Visceral (involuntary) nervous system
  • Function – supplies smooth muscle, cardiac muscle, glands
    • Autonomic nervous system – regulates involuntary motor nerves during flight, fight, freeze conditions
      • Sympathetic system
        • Adjusts response to stressful situations
      • Parasympathetic system
        • Adjusts response when stressful situations have passed

Functional Structures:

• Neuron – nerve cell
  • Sensory – carries impulses towards the central nervous system
  • Motor – carries impulses away from the central nervous system
• Nerve impulse
  • Electric current that spreads along a nerve fibre
• Synapse
  • Junction between neurons where a nerve impulse is transmitted from one neuron to the next
• Nerve
  • Bundle of nerve cell fibres outside the Central Nervous System
• Reflex Arc
  • Pathway through the nervous system

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