Each hand has 27 bones and each foot 26, which makes 106 of the 206 in an adult skeleton. This crowd of small, jointed pieces is what makes fine movements possible: holding a pen, playing an instrument, or adjusting your balance with every step on uneven ground. Your skeleton saves its complexity for the extremities.
Every day, your kidneys filter around 180 liters of blood plasma, about a bathtub's worth. Yet you only have about 3 liters of plasma, so it passes through your kidneys some sixty times a day. Over 99% of the filtered water is reabsorbed, leaving just one to two liters of urine.
A 70 kg adult is made of about 7 × 10²⁷ atoms, or seven billion billion billion. The observable universe is thought to hold on the order of 10²² to 10²⁴ stars. Even with the high estimate, you contain thousands of times more atoms than there are stars in the entire visible cosmos.