Bedi

Overview of Nervous System

  • Discussion of the components of both the central nervous system (CNS) and peripheral nervous system (PNS).

Parts of the Nervous System

  • Central Nervous System (CNS)

    • Comprises the brain and spinal cord.

  • Peripheral Nervous System (PNS)

    • Connects the CNS to the limbs and organs.

Introduction to the Cerebellum

  • Focus on the cerebellum as it relates to day-to-day motor movement.

Brain Functionality

  • Vegetative State

    • Definition: A condition where an individual is alive but not responsive to the external environment.

    • Notably, the heart continues to beat even when the cerebral cortex is destroyed, as long as the brainstem remains intact.

  • Brain Structures

    • Midbrain Components

    • Contains structures such as the superior colliculus and inferior colliculus.

    • Role: Processing sensory input and coordinating motor responses for specific activities (like reflexes).

Sensory Pathways and Nervous System Components

  • Ascending Tract

    • Sensory information travels upward towards the cerebral cortex via the ascending tract.

  • Functional Classification of Nerve Fibers

    • Differentiation between afferent (sensory) and efferent (motor) pathways.

    • Afferent fibers (SA): Responsible for sensory input to the CNS.

    • Efferent fibers (SE): Relay commands from the CNS to effectors (muscles or glands).

Sensory System Overview

  • The sensory system is divided into two major parts:

    • Somatic Sensory

    • Function: Involved in voluntary sensations.

    • Sources: Skin, skeletal muscles, joints, etc.

    • Visceral Sensory

    • Function: Involved in sensations from internal organs.

    • Sources: Heart, spleen, pancreas, kidneys, etc.

Sensory Receptors

  • Different sensory receptors are located on the skin, muscle, and joints to receive sensory inputs.

Motor Control

  • Motor Cortex

    • Function: Controls voluntary motor activity, which is integrated with inputs from the cerebellum and basal ganglia.

  • Neural Activity

    • Neurons as fundamental cells: Their role includes processing information and transmitting signals.

    • Action Potentials: Describe the electrical impulses that neurons use to communicate.

Cellular Components of the Nervous System

  • Neuroglia

    • Includes astrocytes that transport waste products across the blood-brain barrier back to the capillary system.

  • Myelin Sheath

    • An insulating layer around axons, produced by oligodendrocytes and Schwann cells.

Neuronal Structure Features

  • Neurons are characterized as:

    • An elongated structure that connects and communicates with various parts of the body.

Neurotransmitter Dynamics

  • Action of Neurotransmitters

    • Neurotransmitters do not freely float; they are packaged in vesicles within the neuron’s soma.

    • They travel down the axon to the presynaptic terminal where they are stored until required.

  • Vesicle Transport Mechanism

    • Involves proteins like kinesins and dyneins:

    • Kinesins transport vesicles anterogradely (away from the soma).

    • Dyneins mediate retrograde transport (back to the soma).

  • Role of Viruses

    • Some viruses can hijack the neuron’s transport system, primarily via the presynaptic terminal.

Conclusion

  • The discussion of these concepts will continue, exploring more about the nervous system and its functions in subsequent sessions.