(i)The renal artery is a blood vessel that carries oxygenated blood from the heart to the kidneys. It branches off the aorta and travels into the kidney through the hilum. From there it branches further to supply blood to the interior components of the kidney.

(ii)major function of the kidneys is to remove waste products and excess fluid from the body. These waste products and excess fluid are removed through the urine. The production of urine involves highly complex steps of excretion and re-absorption.

(iii)To reabsorb the water lost during filtration. To prevent constant urination and dehydratation.

Function of Renal Artery, Kidney, and Urinary Bladder

Renal artery, kidney, and urinary bladder are important organs of the human body that perform various functions. The function of each organ is explained below:

Renal Artery
The renal artery is responsible for supplying blood to the kidneys. It branches off from the abdominal aorta and enters the kidney at the hilum. The renal artery carries oxygen and nutrients that the kidneys require to function. It also carries waste products and excess water from the kidneys to be excreted. The renal artery plays a crucial role in maintaining the proper functioning of the kidneys.

Kidney
The kidney is a bean-shaped organ located on either side of the spine, just below the ribcage. It performs several vital functions, including:

- Filtration: The kidney filters blood to remove waste products, excess water, and toxins from the body. These waste products are then excreted in the form of urine.
- Regulation of electrolytes and acid-base balance: The kidney maintains the proper balance of electrolytes and pH in the body. It regulates the levels of sodium, potassium, calcium, and other electrolytes in the blood.
- Production of hormones: The kidney produces hormones that regulate blood pressure, stimulate the production of red blood cells, and activate vitamin D.

Urinary Bladder
The urinary bladder is a muscular sac that stores urine before it is excreted from the body. It is located in the pelvic area and can hold up to 600 ml of urine. The bladder has a sphincter muscle at the base, which controls the flow of urine out of the bladder and into the urethra. The bladder is responsible for:

- Storage of urine: The urinary bladder stores urine until it is convenient to excrete it from the body.
- Elimination of urine: The bladder eliminates urine from the body by contracting the muscles in the bladder wall to force urine out through the urethra.

In conclusion, the renal artery, kidney, and urinary bladder are all important organs that perform essential functions in the human body. The renal artery supplies blood to the kidney, which filters waste products and regulates electrolytes and hormone production. The urinary bladder stores and eliminates urine from the body.