Nervous System Basics

Central Nervous System (CNS)

• Consists of the brain and spinal cord
• Protected by the blood-brain barrier
• Functions:
  • Integration of sensory information
  • Control of voluntary movements
  • Regulation of body functions (e.g. heart rate, blood pressure)

Brain

• Divided into three main parts:
  1. Cerebrum: largest part, responsible for sensory perception, movement, and higher-level cognitive functions
  2. Cerebellum: coordinates muscle movements, balance, and posture
  3. Brainstem: connects cerebrum to spinal cord, regulates basic functions (e.g. breathing, heart rate)

Spinal Cord

• Extends from base of brain down to lower back
• Functions:
  • Transmits messages between brain and peripheral nervous system
  • Controls reflexes

Peripheral Nervous System (PNS)

• Consists of nerves that connect CNS to rest of body
• Divided into two subsystems:
  • Somatic Nervous System: controls voluntary movements, transmits sensory information
  • Autonomic Nervous System: controls involuntary functions (e.g. heart rate, digestion)

Nerve Structure

• A nerve consists of:
  • Dendrites: receive signals from other neurons
  • Cell Body: contains nucleus and maintains cell function
  • Axon: carries signals away from cell body
  • Myelin Sheath: insulates and speeds up signal transmission

Glial Cells

• Support cells that provide structure and maintenance for neurons
• Types:
  • Astrocytes: provide nutrients, remove waste
  • Oligodendrocytes: produce myelin sheath
  • Microglia: immune system cells that protect CNS