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Anal Reflex
The anal wink, anal reflex, perineal reflex, or anocutaneous reflex is the reflexive contraction of the external anal sphincter upon stroking of the skin around the anus. A noxious or tactile stimulus will cause a wink contraction of the Anus, anal sphincter muscles and also flexion. The stimulus is detected by the nociceptors in the Perineum, perineal skin to the pudendal nerve, where a response is integrated by the spinal cord sacral segments S2-S4. The absence of this reflex indicates that there is an interruption of the reflex arc, or damage to the spinal cord, which may be in the sensory afferent limb or the motor efferent limb. The synapse between the afferent and efferent limbs occurs in the lowest sacral segments of the spinal cord. See also *Reflex anal dilation References {{reflist Reflexes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reflex
In biology, a reflex, or reflex action, is an involuntary, unplanned sequence or action and nearly instantaneous response to a stimulus. Reflexes are found with varying levels of complexity in organisms with a nervous system. A reflex occurs via neural pathways in the nervous system called 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. These neural signals do not always travel to the brain, so many reflexes are an automatic response to a stimulus that does not receive or need conscious thought. Many reflexes are fine-tuned to increase organism survival and self-defense. This is observed in reflexes such as the startle reflex, which provides an automatic response to an unexpected stimuli, and the feline righting reflex, which reorients a cat's body when falling to ensure safe landing. The simplest type of reflex, a short-latency reflex, has a s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
