The Nervous System: Structure and Function

The nervous system is a complex network that enables organisms to respond to their environment and coordinate behavior. This page introduces the key components and functions of the nervous system.

Central nervous system function: The central nervous system (CNS) consists of the brain and spinal cord. It serves as the main processing center for all neural information.

Vocabulary: CNS - Central Nervous System, the part of the nervous system comprising the brain and spinal cord.

The CNS is connected to the body through two types of neurons:

1. Sensory neurons: These carry information from receptors to the CNS.
2. Motor neurons: These transmit signals from the CNS to effectors.

Definition: Receptors are specialized cells that detect stimuli from the environment. Different receptors are sensitive to specific types of stimuli, such as sound receptors in the ears.

Example: When you touch a hot surface, receptors in your skin detect the heat and send signals to your CNS via sensory neurons.

Peripheral nervous system function: The peripheral nervous system consists of all the nerves outside the CNS. It includes:

• Sensory neurons that carry information from receptors to the CNS
• Motor neurons that transmit signals from the CNS to effectors

Vocabulary: Effectors are structures that respond to signals from motor neurons, such as muscles and glands.

Highlight: Effectors respond to electrical impulses and bring about changes in the body. Muscles contract, while glands release hormones.

This overview provides a foundation for understanding how the nervous system enables organisms to interact with their environment and maintain bodily functions.

Example of a Reflex Action: The Bee Sting Reflex

This page provides a detailed example of a reflex action, specifically the response to a bee sting. This example illustrates the components and sequence of events in a typical reflex arc.

Reflex arc examples: The bee sting reflex demonstrates how quickly and automatically our body can respond to a painful stimulus.

The sequence of events in this reflex arc is as follows:

1. Stimulus: A bee stings your finger.
2. Receptor activation: Pain receptors in the skin detect the sting.
3. Sensory neuron function: Impulses are sent along sensory neurons to the CNS (specifically the spinal cord).
4. CNS processing: In the spinal cord, a relay neuron passes the impulses from the sensory neuron to a motor neuron.
5. Motor neuron function: Impulses are sent along the motor neuron to the effector.
6. Effector response: The effector (in this case, a muscle in the arm) contracts, pulling your hand away from the bee.

Highlight: This entire process happens extremely quickly, often before you're consciously aware of the sting. This rapid response helps minimize damage from the sting.

Sensory and motor neurons function psychology: In this reflex, sensory neurons carry information about the painful stimulus to the CNS, while motor neurons carry commands from the CNS to the muscles to initiate the withdrawal response.

Vocabulary: Relay neuron - A neuron within the CNS that receives signals from sensory neurons and passes them on to motor neurons.

3 types of neurons and functions:

1. Sensory neurons: Carry information from receptors to the CNS
2. Relay neurons: Process and transmit information within the CNS
3. Motor neurons: Carry commands from the CNS to effectors

Example: In addition to the bee sting reflex, other common reflex actions include the knee-jerk reflex, blinking when something approaches your eye, and pulling your hand away from a hot object.

This example of the bee sting reflex demonstrates how the components of the nervous system work together to produce rapid, protective responses to potentially harmful stimuli.