The human nervous system utilizes three main types of neurons, each with a distinct role in transmitting and processing information.
Three Classes of Neurons
Based on their functions, neurons are categorized into:
- Sensory Neurons: These neurons carry information from sensory receptors (e.g., in the skin, eyes, and ears) to the central nervous system (CNS), which includes the brain and spinal cord. They transmit signals about the external and internal environment.
- Example: Sensory neurons in your fingertips send signals to your brain when you touch something hot.
- Motor Neurons: These neurons transmit signals from the CNS to muscles and glands, initiating movement and controlling bodily functions. They are essential for all voluntary and involuntary actions.
- Example: Motor neurons send signals to your leg muscles when you decide to walk.
- Interneurons: These neurons act as intermediaries within the CNS, connecting sensory and motor neurons. They are responsible for processing information, enabling complex reflexes, and higher-level cognitive functions.
- Example: Interneurons in your spinal cord coordinate the withdrawal reflex when you touch something sharp.
| Neuron Type | Function | Direction of Signal |
|---|---|---|
| Sensory Neuron | Carries sensory information to the CNS. | From receptors to CNS |
| Motor Neuron | Transmits signals from the CNS to muscles and glands. | From CNS to muscles/glands |
| Interneuron | Connects sensory and motor neurons within the CNS. | Within the CNS |
These three neuron types work together in a complex communication network, allowing for everything from basic reflexes to conscious thought and movement, as described in the provided reference: “Based on their roles, the neurons found in the human nervous system can be divided into three classes: sensory neurons, motor neurons, and interneurons.”
