Lecture on the Nervous System

Introduction

• Start of the nervous system module, moving on from the skeletal system.
• Focus on structural details in this class; electrophysiology covered in subsequent classes.
• Overview of the nervous system components and functions.
• Three Main Functions:
  1. Sensing/Detecting Environment:
     • External (e.g., temperature, light).
     • Internal (e.g., blood pH, pressure).
  2. Collecting/Summarizing Information:
     • Sensory information amassed by the central nervous system.
  3. Activating Effectors:
     • Glands, muscles (skeletal, smooth, cardiac).

Central vs. Peripheral Nervous System

• Central Nervous System (CNS):

  • Composed of brain and spinal cord.
  • Functions to amass sensory info and make decisions.
  • Protected by bones.
  • Lacks pain receptors of its own.

• Peripheral Nervous System (PNS):

  • All nervous tissue outside CNS.
  • Detects environmental information (internal/external).
  • Carries out CNS decisions.
  • Less protected, more vulnerable.

Anatomical Terms

• CNS Protection:

  • Encased in bone (cranial vault, vertebrae).

• Anatomical Orientation:

  • Dorsal (back) vs. Ventral (belly).
  • Important for spinal cord anatomy.

Neurons and their Functions

• Types of Neurons:

  • Sensory Neurons: Detect and send information to CNS.
    • E.g., Detecting skin pressure.
  • Motor Neurons: Send commands from CNS to effectors.
    • E.g., Muscle contraction.

• Primary Sensory Neurons:

  • Conduct info from body periphery to CNS.

• Motor Neurons:

  • Extend from spinal cord to activate muscles.

Homeostasis Example

• Temperature Regulation:
  • Core body temperature deviation triggers CNS and PNS response.
  • Thermoreceptors detect temperature changes, triggering CNS to act.
  • Effectors activated through efferent action potentials (e.g., shivering).

Cells of the Nervous System

• Neurons and Glial Cells:

  • Neurons: Functional units, communicate through action potentials.
  • Glial Cells: Support neurons, outnumber neurons.

• Roles:

  • Neurons: Detect, integrate, activate.
  • Glial Cells: Support neuronal functions, crucial in brain injury recovery.

Neuron Structure

• Soma (Cell Body): Contains nucleus and organelles.
• Dendrites: Fibrous, surface for stimulus detection.
• Axon: Long fiber conducting action potentials.
• Axon Terminals: Release neurotransmitters to target cells.

Repair and Regeneration

• Neuronal Damage:
  • Repair possible if damage is distally located, preserving soma and proximal axon.
  • Limited regeneration capability.

Summary

• CNS and PNS work in tandem to ensure body functionality.
• Damage to either system affects overall bodily functions.
• Introduction to cellular and anatomical structures sets the stage for deeper study in subsequent modules.