Identify, on diagrams, sensory, relay and motor neurones

Sourav PanNovember 3, 2024

Answered

The nervous system is composed of three main types of neurons: sensory neurons, relay (interneurons), and motor neurons. Each type plays a distinct role in transmitting information throughout the body. Below is a description of each type along with their functions.

Sensory Neurons

• Function: Sensory neurons, also known as afferent neurons, are responsible for transmitting sensory information from sensory receptors (such as those for touch, pain, temperature, and special senses like vision and hearing) to the central nervous system (CNS). They convert stimuli from the external or internal environment into electrical signals (action potentials).
• Structure: Most sensory neurons are either pseudounipolar or bipolar. Pseudounipolar neurons have a single axon that splits into two branches: one extending to the sensory receptor and the other leading to the CNS. This structure allows for efficient transmission of sensory information.

Relay Neurons (Interneurons)

• Function: Relay neurons, or interneurons, act as connectors between sensory neurons and motor neurons within the CNS. They process and integrate sensory information, allowing for reflex actions and complex responses. Interneurons play a crucial role in reflex arcs, where they facilitate quick responses without involving higher brain functions.
• Structure: Interneurons are typically multipolar, meaning they have multiple dendrites and one axon. This structure enables them to receive input from various sources and communicate with multiple other neurons.

Motor Neurons

• Function: Motor neurons, also known as efferent neurons, transmit impulses away from the CNS to effectors such as muscles and glands. They are responsible for initiating movement and regulating bodily functions by controlling muscle contractions and glandular secretions.
• Structure: Motor neurons are also multipolar, characterized by one long axon that extends to the muscle or gland it innervates, along with several dendrites that receive signals from interneurons or directly from the brain.

Summary Diagrammatic Representation

While I cannot display diagrams directly here, you can visualize these neuron types in a simple diagram:

• Sensory Neuron: Depicted with a receptor at one end (e.g., skin) and an axon leading to the spinal cord.
• Relay Neuron: Shown in the spinal cord connecting sensory neurons to motor neurons.
• Motor Neuron: Illustrated with an axon extending from the spinal cord to a muscle.