Final answer:
Infants are more vulnerable to fluid and electrolyte imbalances due to immature neonatal kidneys that produce dilute urine and an inability to control body tonicity. The Apgar score is used to assess a newborn's wellbeing and need for medical care in adapting to the external environment. The initial lack of gastrointestinal bacterial flora also contributes to their susceptibility to imbalances.
Step-by-step explanation:
One reason that infants are more vulnerable to fluid and electrolyte imbalances than adults is that their neonatal kidneys are immature and inefficient at concentrating urine. This leads to production of very dilute urine, requiring infants to obtain adequate fluids to maintain homeostasis. In addition, infants cannot control their tonicity, which is their body's osmotic balance, and they tend to lose more water to their environment than adults. Consequently, maintaining adequate fluid and electrolyte balance is a crucial aspect of neonatal care.
Immediately after birth, an assessment such as the Apgar score can indicate the newborn's general wellbeing and the need for immediate medical care. It also hints at the infant's ability to adapt to life outside the womb where adjustments include dealing with issues like hunger, thirst, and managing body temperature.
Furthermore, infants have yet to develop the gastrointestinal bacterial flora that aids in digestion and protects against pathogens, making them more susceptible to imbalances in the early stages of life. The neonatal period is one where the infant is acclimating to a new world, making it a particularly delicate time for fluid and electrolyte homeostasis.