Unit 5.3

Unit 5: Sensory & Motor Pathways

Overview of the Nervous System

  • Tracts: Groups of axons sharing information, characterized by common destination.

  • Interneurons: Neurons situated between sensory and motor neurons, more prevalent in the Central Nervous System (CNS).

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

  • Peripheral Nervous System (PNS): Comprises nervous tissue external to the CNS and the Enteric Nervous System (ENS).

Nervous System Divisions

  • Afferent Division: Responsible for carrying sensory information to the CNS.

    • Contains sensory pathways including:

    • Somatic Sensory Pathway: Sends information to somatosensory cortex.

    • Visceral Sensory Pathway: Sends information to brainstem & diencephalon (reflex centers).

  • Efferent Division: Carries motor commands from the CNS to the PNS.

    • Contains motor pathways:

    • Somatic Motor Pathways: Sends motor commands to skeletal muscles.

    • Autonomic Pathways: Comprises sympathetic and parasympathetic nervous systems.

Types of Effectors

  • Skeletal Muscles: Under somatic control.

  • Smooth Muscles: Under autonomic control.

  • Cardiac Muscles: Autonomically controlled.

  • Glands: Autonomically controlled.

  • Adipose Tissue: Regulated by autonomic pathways.

Afferent vs Efferent Pathways

Afferent Pathway

  • Carries sensory information from sensory receptors in the PNS to the CNS.

  • Includes:

    • Somatic Sensory: Connects with the somatosensory cortex.

    • Visceral Sensory: Connects with brainstem & diencephalon concerning reflex centers.

Efferent Pathway

  • Carries motor commands from the CNS to the PNS.

  • Divided into:

    • Somatic Motor Pathways: Motor commands directed to skeletal muscles.

    • Autonomic Pathways: Involves both sympathetic and parasympathetic nervous system responses.

Types of Receptors

General Sensory Receptors

  • What is a sensory receptor?

    • Specialized structures that transduce stimuli into action potentials.

    • Types:

    1. Exteroceptors: Provide information about the external environment.

    2. Proprioceptors: Report positions of skeletal muscles and joints.

    3. Interoceptors: Monitor visceral organs and functions.

Sensation vs Perception

  • Sensation: Stimulus receptors reaches CNS

  • Perception: stimulus receptors conscious awareness