Final answer:
Reflex arcs are rapid responses to stimuli involving a neural pathway and the spinal cord. The micturition reflex, specific to the baby's bladder, allows urination and is controlled over time through potty training. Reflexes like the Babinski reflex are normal in infants but can indicate neurological problems if present in adults.
Step-by-step explanation:
The question refers to a reflex arc, a rapid motor response to a sensory stimulus that involves a neural pathway that includes the spinal cord but not the brain. A reflex arc, specifically concerning a baby's bladder, pertains to the micturition reflex. This reflex is responsible for urination and is active in infants. As children mature, they gain control over this reflex through potty training, learning to assert external sphincter control and thus delaying voiding. However, in case of a spinal cord injury resulting in paraplegia or quadriplegia, the micturition reflex may be preserved, although relaxing the external sphincter might not be possible, requiring periodic catheterization.
Infants possess various reflexes, such as the Moro reflex and the grasping reflex, which aid in survival by maintaining close physical contact with their caregiver. Another reflex observed in newborns is the Babinski reflex, where the foot flexes dorsally and the toes splay when the sole of the foot is lightly scratched. This reflex typically disappears as the child grows because full myelination of the neural pathways occurs, rendering the reflex unnecessary. If present in adults, it indicates reduced myelination of the spinal tract, which can be problematic as it suggests potential neurological issues.