Organization of the Nervous System

• What percentage of total body weight does the nervous system constitute?

  About 3%
• What are the primary functions of the nervous system?

  It orchestrates sensory perception, motor control, and cognitive processes.
• What are the two main subdivisions of the nervous system?

  • Central Nervous System (CNS)
  • Peripheral Nervous System (PNS)
• What are the components of the Central Nervous System (CNS)?

  The brain and spinal cord.
• What is the primary function of the Central Nervous System (CNS)?

  It serves as the integrating and control center of the nervous system.
• How does the CNS process incoming sensory information?

  It dictates motor output based on reflexes, current conditions, and past experiences.
• Approximately how many neurons are in the brain?

  About 85 billion neurons.
• Approximately how many neurons are in the spinal cord?

  About 100 million neurons.
• What protects the brain and spinal cord?

  They are enclosed within the skull and vertebral column, respectively.
• What does the Peripheral Nervous System (PNS) consist of?

  All nervous tissue outside the CNS, including nerves and sensory receptors.
• What is the primary function of the Peripheral Nervous System (PNS)?

  It connects the CNS to limbs and organs.
• How many pairs of cranial nerves emerge from the brain?

  12 pairs.
• How many pairs of spinal nerves emerge from the spinal cord?

  31 pairs.
• What are nerves composed of?

  Bundles of axons, connective tissue, and blood vessels.
• What do sensory receptors do?

  They monitor changes in the internal and external environments.
• What are the two divisions of the Peripheral Nervous System (PNS)?

  • Afferent (Sensory) Division
  • Efferent (Motor) Division
• What is the function of the Afferent (Sensory) Division?

  It transmits sensory information from receptors to the CNS.
• What types of sensory information does the Afferent Division transmit?

  Somatic senses and special senses.
• What are somatic senses?

  They include tactile, thermal, nociceptive, and proprioceptive senses.
• What are special senses?

  They include smell, taste, vision, hearing, and equilibrium.
• What is the function of the Efferent (Motor) Division?

  It carries motor commands from the CNS to effectors (muscles and glands).
• What are the subdivisions of the Efferent (Motor) Division?

  • Somatic Nervous System (SNS)
  • Autonomic Nervous System (ANS)
• What does the Somatic Nervous System (SNS) target?

  Skeletal muscles.
• How does the Somatic Nervous System (SNS) control movements?

  It controls voluntary (conscious) movements.
• What does the Autonomic Nervous System (ANS) target?

  Smooth muscle, cardiac muscle, and glands.
• How does the Autonomic Nervous System (ANS) control functions?

  It controls involuntary (automatic) functions.
• What are the subdivisions of the Autonomic Nervous System (ANS)?

  • Sympathetic Nervous System
  • Parasympathetic Nervous System
• What is the function of the Sympathetic Nervous System?

  It prepares the body for "fight-or-flight" responses.
• What effects does the Sympathetic Nervous System have on the body?

  It increases heart rate, dilates pupils, and inhibits digestion.
• Where is the Sympathetic Nervous System located?

  Thoracolumbar area.
• What is the function of the Parasympathetic Nervous System?

  It promotes "rest-and-digest" activities.
• What effects does the Parasympathetic Nervous System have on the body?

  It decreases heart rate, constricts pupils, and stimulates digestion.
• Where is the Parasympathetic Nervous System located?

  Craniosacral area.
• What is the function of the Enteric Nervous System (ENS)?

  It regulates the gastrointestinal (GI) tract.
• How does the Enteric Nervous System (ENS) operate?

  It can operate independently but interacts with sympathetic and parasympathetic systems.
• What is an example of the Enteric Nervous System (ENS) function?

  Controlling peristalsis in the intestines.
• What is neurology?

  • The branch of medicine focused on the nervous system.
  • Includes studying neurological diseases, diagnosing disorders, and developing treatments.
• What is a neurologist?

  A physician specialized in neurology.
• What role does a neurologist play?

  Diagnoses and treats disorders of the nervous system.
• What are the three basic types of functions performed by the nervous system?

  • Sensory (Input) Function
  • Integrative (Process) Function
  • Motor (Output) Function