Final answer:
Potassium ions, hydrogen ions, ammonia ions, and drugs like penicillin can all be eliminated from the blood via tubular secretion. This process is crucial for maintaining the body's acid-base balance and removing various waste products. Specific carriers facilitate the secretion of drugs into the renal tubule lumen.
Step-by-step explanation:
The substances that can be eliminated from the blood by tubular secretion include potassium ions (K+), hydrogen ions (H+), ammonia ions (NH3), and certain drugs such as penicillin. Tubular secretion is a process by which the kidneys remove excess substances from the blood and directly secrete them into the tubule lumen. Specific carriers in the renal tubules help in the secretion of drugs, with different carriers for basic and acidic drugs. This process allows for the precise regulation of blood composition by the kidneys.
Acid-base balance is also maintained through the secretion and reabsorption of H+ and bicarbonate ions (HCO3-), ensuring the body's pH remains stable. Water and various electrolytes, such as sodium (Na+), are reabsorbed as necessary, but other substances like potassium, hydrogen, ammonia, creatinine, and some drugs like penicillin are secreted as waste. By exchanging ammonia ions and hydrogen ions, the body can effectively regulate acid-base balance and remove waste products.