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A&P2 - Division of Nervous System

Nervous System Overview

  • The nervous system and endocrine system both function to communicate and control various processes in the body.

  • Key Functions: Communication, Integration, and Control.

Nervous System Composition

  • Main Components: 3 main parts of the nervous system are:

    • Brain

    • Spinal Cord

    • Nerves (peripheral nerves that branch from the brain and spinal cord)

Divisions of the Nervous System

  • Central Nervous System (CNS): Comprises the brain and spinal cord.

    • Function: Processes sensory information and initiates responses.

  • Peripheral Nervous System (PNS): Comprises nerves that emerge from the CNS.

    • Types of Nerves:

    • Cranial Nerves: Emanate from the brain.

    • Spinal Nerves: Emanate from the spinal cord.

Functionality of the Nervous System

  • The nervous system;

    • Detects internal and external environmental changes.

    • Evaluates information.

    • Initiates appropriate responses via a feedback loop mechanism.

Sensory Pathways

  • Afferent Division:

    • Function: Transmits sensory (incoming) information to the CNS.

    • Keywords: Incoming, Sensory, Ascending.

    • Example: Sensory information from the leg about temperature or pain is reported to the CNS.

  • Efferent Division:

    • Function: Carries motor (outgoing) information away from the CNS.

    • Keywords: Outgoing, Motor, Descending.

    • Example: CNS triggers a response to move the leg away from a heat source.

Somatic vs. Autonomic Nervous System

  • Somatic Nervous System:

    • Controls voluntary movements of skeletal muscles.

    • Follows an afferent/efferent pathway for conscious control.

  • Autonomic Nervous System:

    • Controls involuntary bodily functions (e.g., heart rate, digestion).

    • Functions without conscious control, acting automatically.

Subdivisions of the Autonomic Nervous System

  • Sympathetic Division:

    • Response: Activates fight or flight mechanisms (increases heart rate, blood pressure).

  • Parasympathetic Division:

    • Response: Engages rest and digest processes (maintains bodily functions during rest).

Distinction of Functions

  • Motor Control: Not all motor functions refer to skeletal muscle activity. It can include gland functions as well, such as salivation.

  • Importance of Dual Innervation: Both sympathetic and parasympathetic divisions have control over autonomic organs, allowing precise regulation of their functions.

Conclusion

  • The nervous system is complex, characterized by distinct but interconnected components and pathways that facilitate communication through sensory input and motor responses. Understanding the subdivisions and their functions is critical for grasping how the body maintains homeostasis and responds to stimuli.