Nervous system

• Functions of the nervous system

  Detects external and internal stimuli (Sensory Input)<|>Processes and responds to sensory input (Integration)<|>Controls muscles and glands<|>Maintains homeostasis by regulating other systems<|>Center for mental activities
• Structural classification of the nervous system

  • Central Nervous System (CNS)
  • Peripheral Nervous System (PNS)
• Functional classification of the nervous system

  • Sensory (Afferent) Division
  • Motor (Efferent) Division
• Subdivisions of the Motor (Efferent) Division

  • Somatic Nervous System
  • Autonomic Nervous System (ANS)
• Central Nervous System (CNS)


  Brain and Spinal Cord<|>Functions: Integration, Command Center<|>Interprets sensory information and issues instructions
• Peripheral Nervous System (PNS)


  Nerves outside CNS<|>Includes Spinal Nerves and Cranial Nerves<|>Links the body to the CNS through sensory and motor nerves
• Sensory (Afferent) Division


  Sensory Receptors → CNS
• Motor (Efferent) Division


  CNS → Effectors
• Functions controlled by the Motor (Efferent) Division


  • Contraction of skeletal muscles throughout the body
  • Contraction of smooth muscle in the internal organs
  • Secretion of active chemical substances by both exocrine and endocrine glands in many parts of the body
• Subdivisions of the Motor (Efferent) Division

  • Somatic (Voluntary)
  • Visceral (Involuntary or Autonomic)
  • Special
• Visceral (Involuntary or Autonomic)


  Controlled by the Sympathetic and Parasympathetic NS
• Neuronal circuits in the spinal cord

  Can cause walking movement<|>Reflexes that withdraw parts of the body from painful stimuli<|>Reflexes that stiffen the legs to support the body against gravity<|>Reflexes that control local blood vessels, gastrointestinal movements, and urinary excretion
• Major levels of CNS functions

  • Spinal Cord Level
  • Lower Brain or Subcortical Level
  • Higher Brain (Cortical Level)
• Cerebellum


  Coordinates voluntary movements such as posture, balance and coordination, resulting in smooth and balanced muscular activity
• Thalamus


  Relay center for sensory and motor signals to the cerebral cortex
• Hypothalamus


  Regulates homeostasis, emotional responses, temperature, sleep and controls the endocrine system<|>Produces hormones (e.g. ADH, Oxytocin)
• Basal ganglia


  Regulates movement and motor control
• Pons


  Relays signals between cerebrum and cerebellum, regulates breathing
• Mesencephalon (Midbrain)


  Processes visual and auditory information, involved in motor control
• Cerebral Cortex


  The cortex never acts alone; it works in association with the lower brain centers<|>Integrates and refines the inputs from lower brain centers, playing a vital role in complex thought processes, memory, and precise execution of functions
• Lobes of the cerebral cortex

  • Frontal lobe
  • Parietal Lobe
  • Temporal Lobe
  • Occipital Lobe
• Primary Motor Cortex (Area 4)


  Location: Precentral gyrus<|>Initiates delicate isolated movements
• Premotor Cortex (Area 6)

  Location: Anterior to the primary motor cortex<|>Produce automatic actions; initiates grasp reflex
• Frontal Eye Field (Area 8)

  Location: Anterior to the premotor cortex<|>Controls voluntary eye movements
• Prefrontal area (Areas 9, 10 and 12)


  Autonomic, Mental, Memory, Behaviour, Personality
• Broca's Area (Area 44, 45)


  Location: Inferior frontal gyrus<|>Speech production and language processing
• Primary Somatosensory Cortex (Area 3, 1, 2)

  Location: Postcentral gyrus<|>Processes sensory information from the body (touch, temperature, pain)
• Primary Auditory Cortex (Area 41, 42)

  Location: Superior temporal gyrus<|>Processes auditory information
• Wernicke's Area (Area 22)


  Location: Posterior superior temporal gyrus<|>Function: Language comprehension
• Frontal Lobe


  Involved in decision-making, problem-solving, planning, and voluntary motor activity
• Parietal Lobe


  Processes sensory information such as touch, temperature, & pain
• Occipital Lobe


  Primary center for visual processing
• Temporal Lobe


  Involved in hearing, memory, and speech
• Primary Motor Cortex


  Located in the precentral gyrus of the frontal lobe; controls voluntary movements
• Primary Somatosensory Cortex


  Located in the postcentral gyrus of the parietal lobe; processes sensory information from the body
• Nervous tissue


  Made up of just two principal types of cells—supporting cells and neurons
• Supporting cells (Neuroglia, Glia or Glial cells)

  • Astrocytes
  • Ependymal cells
  • Microglia
  • Oligodendrocytes
• Supporting cells in the PNS

  • Schwann cells
  • Satellite cells
• Astrocytes


  Star-shaped<|>Form a supportive framework for blood vessels and neurons<|>Promote the formation of tight junctions in the blood-brain barrier<|>Reactive astrocytosis<|>Promote synapse development and regulate neurotransmitter activity
• Ependymal cells


  Line the central cavities of the brain and the spinal cord<|>Produce and circulate cerebrospinal fluid (CSF)