Introduction to nervous systems test 3 lecture

Oct 13, 2024

Nervous System Overview

Functions of the Nervous System

  • Feedback Cycle: Consists of sensory receptors, input, control center, output, and effectors.
    • Sensory Receptors: Detect stimuli (e.g., thirst)
    • Input: Electrical signals sent to the control center
    • Control Center: Analyzes and evaluates information (brain/spinal cord)
    • Output: Electrical signals to effectors (muscles, glands)
    • Effectors: Can be any cell type in the body
  • Signal Control: All signaling in the nervous system involves electrical signals for input and output.

Major Functions

  1. Sensory Function
    • Transfers information from peripheral to central body parts
    • Conducted by Sensory Neurons (aka Afferent Neurons)
  2. Integrative Function
    • Occurs in the control center (brain or spinal cord)
    • Involves Interneurons (aka Association Neurons)
    • Located in gray matter (neurons without myelin sheath)
  3. Motor Function
    • Transfers information from central to peripheral body parts
    • Conducted by Motor Neurons (aka Efferent Neurons)

Nervous System Organization

  • Central Nervous System (CNS)
    • Comprises the brain and spinal cord
    • Centrally located in the body
  • Peripheral Nervous System (PNS)
    • Comprises cranial nerves, spinal nerves, ganglia, receptors
    • Further subdivided into somatic and autonomic systems

Peripheral Nervous System

  • Somatic Nervous System
    • Serves skeletal muscles
    • Somatic Sensory Neurons: Relay information from skeletal muscles to CNS
    • Somatic Motor Neurons: Relay information from CNS to skeletal muscles
    • Associated with voluntary control and conscious awareness
  • Autonomic Nervous System
    • Involves involuntary controls (smooth muscle, cardiac muscle, glands)
    • Sympathetic Division:
      • "Fight or Flight" response
      • High energy, emergency situations
    • Parasympathetic Division:
      • "Rest and Digest" response
      • Increases digestion, defecation, diuresis
      • Operates during calm states and after meals

Key Concepts

  • Afferent vs. Efferent:
    • Afferent (Sensory): Information to CNS
    • Efferent (Motor): Information from CNS
  • Autonomic System Divisions:
    • Sympathetic: High energy, emergency
    • Parasympathetic: Calming, energy conservation
  • Components of PNS: Everything except brain and spinal cord

This structure outlines the key elements and functions of the nervous system, highlighting the relationship between sensory, integrative, and motor functions and their roles in maintaining body homeostasis through different pathways and divisions.