What bodily process involves both the bladder and urethra?

The bodily process that involves both the bladder and the urethra is excretion. Excretion is the final stage of urine formation, where urine, produced in the kidneys, is transported and stored in the bladder. Once the bladder fills to a certain capacity, the urine is expelled through the urethra. This process is critical for the elimination of waste products and excess substances from the body, thus maintaining homeostasis.

Filtration primarily occurs in the kidneys, where blood is filtered to form urine. Absorption refers to the process of nutrients and water being reabsorbed back into the bloodstream, mainly happening in the renal tubules after filtration. Secretion is involved in moving additional waste products from the blood into the urine, also occurring in the kidneys. While these processes are interconnected within the urinary system, excretion specifically encompasses the functions of both the bladder and urethra in the elimination of urine from the body.