Lecture Summary: Nervous System Fundamentals

Introduction

• Morning activities and the nervous system's role (e.g., waking up, feeling cold, making toast, letting the dog out, drinking tea).
• Nervous system controls all physiological and psychological reactions.

Importance of the Nervous System

• Controls all organs and reactions, both physiological and psychological.
• Essential for all animals, including humans.
• Key focus: anatomy, organization, covvfdvfmmunication, and damage response.

Functions of the Nervous System

• Sensory Input: Detects stimuli (e.g., spider on skin).
• Integration: Processes and decides on action (e.g., remain calm or react).
• Motor Output: Executes response (e.g., swatting spider).

Components of the Nervous System

Central Nervous System (CNS)

• Brain and Spinal Cord: Main control center.

Peripheral Nervous System (PNS)

• Nerves: Connect CNS to the body.
• Sensory (Afferent) Division: Receives sensory information.
• Motor (Efferent) Division: Sends instructions from CNS to muscles/glands.
  • Somatic (Voluntary) Nervous System: Controls skeletal muscles.
  • Autonomic (Involuntary) Nervous System: Controls heart, lungs, stomach.
    • Sympathetic Division: Activates body (fight or flight).
    • Parasympathetic Division: Calms the body.

Nervous Tissue

• 80% Cells: Densely packed with cells (neurons and glial cells).
• Neurons: Nerve cells that transmit signals.
  • Long-lived, irreplaceable, high metabolic rate.
  • Structure: Soma (cell body), Dendrites (listeners), Axon (talker).
• Glial Cells: Support and protect neurons.
  • Central Nervous System:
    • Astrocytes: Anchor neurons, exchange materials.
    • Microglial Cells: Immune defense.
    • Ependymal Cells: Create and circulate cerebrospinal fluid.
    • Oligodendrocytes: Produce myelin sheath.
  • Peripheral Nervous System:
    • Satellite Cells: Support neuron cell bodies.
    • Schwann Cells: Produce myelin sheath.

Types of Neurons

• Multipolar Neurons: Multiple processes (one axon, many dendrites).
• Bipolar Neurons: Two processes (one axon, one dendrite).
• Unipolar Neurons: One process (mainly in sensory receptors).

Functional Classification of Neurons

• Sensory (Afferent) Neurons: Transmit impulses to CNS.
• Motor (Efferent) Neurons: Transmit impulses from CNS to muscles/glands.
• Interneurons: Connect sensory and motor neurons within CNS.

Applied Example: Spider on Knee

• Sensory neurons detect spider, signal travels to spinal cord and brain.
• Interneurons process signal, decide reaction (kick leg, scream, or remain calm).

Conclusion

• Nervous system components and their roles in sensory input, integration, and motor output.
• Next lesson will cover nerve cell communication through chemistry and electricity.
• Acknowledgment of contributors and supporters.