Part1

• 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
• Divisions of the Sensory (Afferent) Division

  • Sensory Receptors → CNS
• Divisions of the Motor (Efferent) Division


  • CNS → Effectors
• Somatic Nervous System


  Voluntary Control
• Autonomic Nervous System


  Involuntary Control
• The Somatic Nervous System controls the contraction of skeletal muscles throughout the body
• The Autonomic Nervous System controls the contraction of smooth muscle in the internal organs and the secretion of active chemical substances by both exocrine and endocrine glands in many parts of the body
• Subdivisions of the Autonomic Nervous System

  • Sympathetic
  • Parasympathetic
• Spinal Cord Level


  Neuronal circuits in the 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
• 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
• 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
• Lobes of the cerebral hemispheres

  • Frontal Lobe
  • Parietal Lobe
  • Occipital Lobe
  • Temporal Lobe
• 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
• Supporting cells


  Non-neuronal cells that support, protect, and maintain neurons in the nervous system<|>Also known as neuroglia, glia or glial cells
• Types of supporting cells in the CNS

  • Astrocytes
  • Ependymal cells
  • Microglia
  • Oligodendrocytes
• Types of 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)
• Microglia


  Spider-like phagocytes (CNS-specific immune cells)<|>Increase in areas of CNS damage (e.g., due to infection, trauma, or stroke)
• Oligodendrocytes


  Form myelin sheaths around axons in the CNS<|>One oligodendrocyte can myelinate multiple axons
• Schwann Cells


  Form myelin sheaths around axons in the PNS<|>Each Schwann cell myelinates a segment of a single axon