Human Neural System – Class 11 | Chapter – 21 | Biology Short Notes Series PDF

Human Neural System: The human neural system is a complex network of neurons specialized to carry messagesThe complexity of the nervous system increases as we move towards higher animals.

Parts of Human Neural System

  • Central neural system (CNS): The CNS includes the brain and the spinal cord and is the site of information processing and control.
  • Peripheral neural system (PNS): The PNS comprises of all the nerves of the body associated with the CNS (brain and spinal cord).

Central Neural System (CNS)

  • The brain is the central information processing organ of our body, and acts as the ‘command and control system’.
  • It controls the voluntary movements, balance of the body, functioning of vital involuntary organs (e.g., lungs, heart, kidneys, etc.), thermoregulation, hunger and thirst, circadian (24-hour) rhythms of our body, activities of several endocrine glands and human behavior.
  • It is also the site for processing of vision, hearing, speech, memory, intelligence, emotions and thoughts.
  • The human brain is well protected by the skull. Inside the skull, the brain is covered by cranial meninges consisting of an outer layer called dura mater, a very thin middle layer called arachnoid and an inner layer (which is in contact with the brain tissue) called pia mater.

Peripheral Neural System (PNS)

The nerve fibres of the PNS are of two types:

  1. afferent fibres → tissues/organs to brain.
  2. efferent fibres → brain to tissues/organs.
  • The afferent nerve fibres transmit impulses from tissues/organs to the CNS and the efferent fibres transmit regulatory impulses from the CNS to the concerned peripheral tissues/organs.
  • The PNS is divided into two divisions called somatic neural system and autonomic neural system.
  • The somatic neural system relays impulses from the CNS to skeletal muscles while the autonomic neural system transmits impulses from the CNS to the involuntary organs and smooth muscles of the body.
  1. Somatic Neural System → Brain to Voluntary muscles.
  2. Autonomic Neural System → Brain to Involuntary muscles.
  • The autonomic neural system is further classified into sympathetic neural system and parasympathetic neural system.

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By Team Learning Mantras