Question

Describe the structure of a Neuron and explain Reflex Action.

Hint:

A neuron consists of a cell body, dendrites, and an axon. Reflex action is a rapid and automatic response to a stimulus controlled mainly by the spinal cord through a reflex arc.

Answer 1

Concept: The nervous system controls and coordinates various activities of the body. The basic structural and functional unit of the nervous system is the neuron (nerve cell). Neurons transmit electrical impulses throughout the body. A rapid, automatic response to a stimulus that does not involve conscious thinking is called a reflex action.
Step 1:Structure of a Neuron.
A neuron is a specialized cell designed to transmit nerve impulses. It consists of three main parts:

• Cell Body (Cyton): It contains the nucleus and cytoplasm and controls the activities of the neuron.
• Dendrites: These are short, branched extensions that receive nerve impulses from other neurons and transmit them toward the cell body.
• Axon: It is a long fiber-like extension that carries nerve impulses away from the cell body to another neuron, muscle, or gland.

Some axons are covered by a protective fatty layer called the myelin sheath, which helps in faster transmission of nerve impulses.
Step 2:Reflex Action.
Reflex action is a quick and automatic response of the body to a stimulus without the involvement of conscious thinking. Examples:

• Pulling the hand away immediately after touching a hot object.
• Blinking of eyes when dust enters the eye.

Step 3:Reflex Arc.
The pathway followed by nerve impulses during a reflex action is called a reflex arc. It includes the following components:

• Receptor: Detects the stimulus.
• Sensory neuron: Carries impulses from the receptor to the spinal cord.
• Interneuron: Located in the spinal cord and processes the impulse.
• Motor neuron: Carries impulses from the spinal cord to the effector.
• Effector: Muscle or gland that produces the response.

Reflex actions are mainly controlled by the spinal cord, which allows the body to respond quickly to harmful stimuli.