Nervous System Study Guide

Anatomical Organization and General Functions of the Nervous System

• Central Nervous System (CNS): Brain and spinal cord; integrates and processes information.

• Peripheral Nervous System (PNS): Nerves and ganglia outside CNS; connects CNS to limbs and organs.

• Functions:

• Sensation: Detect internal and external stimuli.

• Integration: Interpret sensory input and coordinate responses.

• Response: Initiate voluntary/involuntary reactions.

Neurons vs. Neuroglia

• Neurons:

• Transmit electrical impulses.

• Structures: Cell body, dendrites (receive input), axon (sends signals).

• Neuroglia (Glial Cells):

• Support, nourish, and protect neurons.

• CNS Types:

  • Oligodendrocytes: Myelin sheaths around axons.

  • Astrocytes: Maintain blood-brain barrier, nutrients.

  • Microglia: Immune cells, eat pathogens.

  • Ependymal cells: Produce and move cerebrospinal fluid (CSF).

• PNS Types:

  • Schwann cells: Myelin sheath, nerve regeneration.

  • Satellite cells: Chemical environment support.

Protection of the Brain and Spinal Cord

• Meninges:

• Dura mater (outer), arachnoid mater (middle), pia mater (inner).

• Cerebrospinal Fluid (CSF): Cushions the brain and spinal cord, circulates nutrients.

• Structural Protection: Skull and vertebral column protect CNS.

• Blood-Brain Barrier: Selective permeability that protects the brain.

Major Brain Regions and Functions

• Frontal Lobe: Motor control, decision-making, problem-solving, speech production.

• Parietal Lobe: Sensory processing, spatial awareness.

• Temporal Lobe: Auditory processing, memory.

• Occipital Lobe: Visual processing.

• Cerebrum: Largest part, motor control, sensory perception.

• Corpus Callosum: Connects brain hemispheres.

• Cerebral Cortex: Outer layer for conscious thought and movement.

• Precentral Gyrus: Primary motor cortex.

• Postcentral Gyrus: Primary somatosensory cortex.

• Diencephalon:

• Thalamus: Sensory relay.

• Hypothalamus: Homeostasis regulation.

• Brainstem:

• Midbrain: Sensory and motor integration.

• Pons: Connects to the cerebellum, sleep, arousal.

• Medulla Oblongata: Controls heart rate and respiration.

• Cerebellum: Coordination and balance.

Spinal Cord and Spinal Nerves

• Divided into cervical, thoracic, lumbar, and sacral regions.

• Gray Matter: Processes signals; forms horns.

• White Matter: Communicates sensory and motor signals.

Neural Reflexes

• Involuntary, predictable responses.

• Somatic Reflexes: Skeletal muscle (e.g., withdrawal reflex).

• Autonomic Reflexes: Smooth/cardiac muscle, glands.

Somatic vs. Autonomic Nervous System

• Somatic: Voluntary control of skeletal muscles.

• Autonomic: Involuntary control of glands and muscles, includes:

• Sympathetic (fight or flight) vs. Parasympathetic (rest and digest).

Cranial Nerves Summary

• Total: 12 pairs of cranial nerves; examples include:

• Olfactory (I): Smell

• Optic (II): Vision

• Vagus (X): Heart, lungs, digestion.

Special Senses

• Taste: Five tastes: sweet, sour, salty, bitter, umami.

• Smell: Olfactory receptor cells process signals.

• Hearing: Cochlea responds to sound waves.

• Balance: Detects movement and position.

• Vision: Processes light with rods and cones.

Integration Summary

• The nervous system integrates sensory input and coordinates appropriate motor outputs, maintaining homeostasis and bodily function.