refleksikaari

Refleksikaari, Finnish for reflex arc, is the neural pathway that mediates a reflex action, enabling automatic and rapid responses to stimuli without conscious thought. A typical reflex arc starts with a receptor that detects a stimulus and generates a sensory signal, which travels along a sensory neuron to the central nervous system. At an integrating center, usually located in the spinal cord or brainstem, the signal is processed and transmitted via a motor neuron to an effector, most often a muscle or gland, which executes the response. Some reflexes also involve interneurons and may be modulated by higher brain centers.

Refleksikaaret are commonly categorized as monosynaptic or polysynaptic. A monosynaptic reflex arc features a direct synapse between a sensory and a motor neuron, producing a very fast response, as in the patellar tendon reflex. Polysynaptic reflex arcs involve one or more interneurons, allowing more complex processing, inhibition, and coordination, as seen in withdrawal and crossed extensor reflexes.

Examples of reflex arcs include the patellar reflex, Achilles reflex, pupillary light reflex, and corneal reflex. Functionally, reflex arcs help maintain posture and balance, protect the body from injury, and coordinate simple motor activities largely independent of conscious control.

Clinically, reflex testing evaluates the integrity of peripheral nerves, spinal pathways, and neuromuscular function. Abnormal reflexes, such as hypo- or hyperreflexia or the presence of pathological reflexes, can indicate neurological or neuromuscular disorders.