The Nervous System
The nervous system is a complex network that coordinates bodily functions and responses. It consists of two main parts: the central nervous system (CNS) and the peripheral nervous system.
The central nervous system comprises the brain and spinal cord, which process information at a speed of about 0.5 m/s. The peripheral nervous system includes all other nerve cells that connect to the CNS.
Definition: Neurons are specialized cells that carry messages as electrical impulses throughout the body.
There are three types of neurons:
- Sensory neurons: Carry impulses from receptors to the CNS
- Relay neurons: Pass impulses to motor neurons
- Motor neurons: Transmit impulses to effectors (muscles or glands) that produce a response
Vocabulary: A synapse is the gap between two neurons where neurotransmitters are released to transmit signals.
When an impulse reaches a synapse, it stimulates the release of neurotransmitters (chemicals) that diffuse across the gap and bind to receptors on the next neuron, triggering a new electrical impulse.
Highlight: The function of neurons in the nervous system is crucial for rapid communication and response to stimuli.
Coordinated Response vs. Reflex Action
A coordinated (voluntary) response involves multiple steps and decision-making by the brain. This process takes around 0.7 m/s and allows for a more complex reaction to stimuli.
Definition: Reflexes are automatic, involuntary responses that do not involve conscious thought and occur much faster, at about 0.2 m/s.
Reflexes serve to protect the body and do not involve the brain in the response process. This distinction between coordinated response versus reflex action is essential for understanding how the nervous system functions in different situations.
