C.
1. Kidney
2. Ureter
3. Bladder
4. Urethra
D.
Kidney
-The kidneys act as very efficient filters for ridding the body of waste and toxic substances, and returning vitamins, amino acids, glucose, hormones and other vital substances into the bloodstream.
Ureters
-These narrow tubes carry urine from the kidneys to the bladder. Muscles in the ureter walls continually tighten and relax forcing urine downward, away from the kidneys.
Urinary Bladder
-The bladder is an organ of the urinary system. It plays two main roles: Temporary storage of urine – the bladder is a hollow organ with distensible walls. It has a folded internal lining (known as rugate), which allows it to accommodate up to 400-600ml of urine in healthy adults.
Urethra
-This tube allows urine to pass outside the body. The brain signals the bladder muscles to tighten, which squeezes urine out of the bladder. At the same time, the brain signals the sphincter muscles to relax to let urine exit the bladder through the urethra.
