Sub Systems of Nervous System

Nervous System Overview
  • Main Functions:
    • Receive information
    • Process information
    • Coordinate response to information
Subdivisions of the Nervous System

  • Central Nervous System (CNS):

    • Comprises brain and spinal cord
    • Processes information from internal and external environments and activates responses

  • Peripheral Nervous System (PNS):

    • Carries messages to/from the CNS
    • Comprises two main divisions: Somatic and Autonomic
Somatic Nervous System (SNS)
  • Function: Controls voluntary movements
  • Sensory Pathways:
    • Afferent (incoming) sensory information travels to the CNS from sensory receptors
  • Motor Pathways:
    • Efferent (outgoing) motor information travels from the CNS to skeletal muscles
Autonomic Nervous System (ANS)
  • Function: Connects CNS with internal organs and glands; operates involuntarily
  • Divisions of ANS:
    • Sympathetic NS:
    • Prepares body for action (e.g., fight or flight responses)
    • Parasympathetic NS:
    • Calms body (e.g., rest and digest)
The Brain
  • Divided into three main parts:
    • Forebrain: Cognitive processes, emotion, and personality
    • Midbrain: Movement, sensory processing, sleep/wakefulness
    • Hindbrain: Vital functions such as heart rate and breathing
Role of the Spinal Cord
  • Connects brain to PNS
  • Functions:
    • Receive sensory information from PNS and send to brain
    • Receive motor commands from brain and send to body
    • Involved in reflex actions (spinal reflex) that occur without brain input
Neurotransmitters
  • Function in the nervous system:
    • Transmit neural information across synapses
    • Excitatory Example: Glutamate
    • Inhibitory Example: GABA
    • Neuromodulators: Dopamine and serotonin affect overall brain activity
Synaptic Plasticity
  • Mechanisms: Long-term potentiation and long-term depression
    • Involved in memory formation and learning through processes such as sprouting, rerouting, and pruning
Conscious vs Unconscious Responses
  • Conscious Responses:
    • Involve awareness and intentional action
    • Processed through the brain and spinal cord
  • Unconscious Responses:
    • Automatic and do not require awareness (e.g., breathing)
    • Spinal reflex involves sensory input leading to motor output without brain involvement
Examples of Responses
  • Spinal Reflex Example:
    • Stepping on a pin leads to an immediate withdrawal of the foot via the spinal reflex arc
  • Conscious Example:
    • Turning on a hot tap after feeling cold water
Enteric Nervous System (ENS)
  • Functions autonomously within the gastrointestinal tract
  • Involves a complex network of neurons dedicated to digestive processes (estimated 400-600 million neurons)
Quick Tips for Exam Preparation
  • Remember: Sympathetic = Stress; Parasympathetic = Peace
  • Acronym SAME for remembering sensory (Afferent) and motor (Efferent) pathways
  • Be clear on roles and functions of ANS divisions for exam questions
  • Clarify between conscious/unconscious tasks using keywords
  • Understand structural elements of neurons and how they function to transmit signals.
Important Note on Terminology
  • Autonomic is often confused with Automatic; remember to use correct terminology in exams to avoid losing marks.