Final answer:
The estimate of bladder volume using the formula (age + 1) × 30ml is a general guideline and may not accurately reflect individual variations; a smaller child may have a smaller bladder. Fetal weight exerting pressure on the bladder is an example of how physiology can affect bladder capacity.
Step-by-step explanation:
Estimating Bladder Volume in Children
The formula (age + 1) × 30 to estimate bladder volume in milliliters is a rough guide and may not take into account individual variations such as a child's size and weight. For a 10-year-old child, this formula would suggest a bladder volume of 330ml (10 + 1) × 30. However, as you mentioned, a smaller and thinner child may indeed have a smaller bladder. Bladder capacity can vary widely amongst children.
Regarding fetal pressure on a mother's bladder: A full-term fetus with a mass of 3.50kg exerts pressure when resting on a mother's bladder. This pressure, when calculated over an area of 90.0 cm², can be substantial, and when converted to millimeters of mercury, helps us understand whether it is sufficient to trigger the micturition reflex.
Physiologically, the growth and development patterns may suggest that a child's organ sizes, including the bladder, often correlate with their general body size. Thus, factors like weight, height, and growth rate can be considered alongside age when estimating organ capacity.