Reflexes and the Nervous System

Reflexes in Biology

• A reflex is an involuntary, unplanned sequence or action and nearly instantaneous response to a stimulus.
• Reflexes are found in organisms with a nervous system, with varying levels of complexity.
• Reflexes occur via neural pathways in the nervous system called reflex arcs.

Reflex Arcs

• A stimulus initiates a neural signal, which is carried to a synapse.
• The signal is then transferred across the synapse to a motor neuron, which evokes a target response.
• Neural signals do not always travel to the brain, allowing many reflexes to be automatic responses to a stimulus without conscious thought.

Types of Reflexes

• Many reflexes are fine-tuned to increase organism survival and self-defense.
• Examples of reflexes include the startle reflex, which provides an automatic response to an unexpected stimulus.
• The feline righting reflex reorients a cat's body when falling to ensure safe landing.

Short-Latency Reflex

• A short-latency reflex is the simplest type of reflex.
• It has a single synapse.