The kidney is referred to as an excretory organ because it excretes wastes. it is also a major homeostatic organ because it maintains the electrolyte, , and balance of the blood. urine is continuously formed by the and is routed down the by the mechanism of to a storage organ called the . eventually, the urine is conducted to the body by the urethra. in the male, the urethra is centimeters long and transports both urine the female urethra centimeters long and transports only urine. voiding or emptying the bladder is called voiding has both voluntary and involuntary components. the voluntary sphincter is the sphincter. an inability to control this sphincter is referred to as

The answers that are meant for the blanks spaces are listed below according to their numbers:
1. Nitrogenous
Nitrogenous wastes refers to metabolic wastes that contain nitrogen; two examples of these are urea and uric acid.
2.Water
3. Acid base
Kidney is an osmoregulatory organ, it participates in homeostasis by regulating the amount of water, electrolytes and the concentration of acid base balance in the body. It does this by means of various mechanisms which ensure that the internal environment of the body is kept constant.
4. Kidney
There are two kidneys in the body, they are responsible for urine production. They do this by filtering the blood and removing wastes, the wastes are then processed into urine and remove from the body.
5. Ureters
6. Peristalsis
7. Urinary bladder
Urine production involves the ureters, urinary bladder and urethra, these three form the urinary tract which act as a plumbing system that drain urine away from the kidneys.
8. Exterior
Urethra is the conducting pipe which leads the urine to the outside of the body for excretion.
9. 20 centimeter  
10. Semen
The urethra is a tube like structure, which is approximately 8 inches long in male, this is equivalent to 20 centimeters. It is used for the transportation of urine and semen.
11. 4 centimeter
In female, the urethra is between one to two inches long, which is equivalent to 4 centimeter.
12. Urination or micturition.
The process of passing the urine out of the body through the urethra is called urination.
13. The external urethral sphincter 
The urethral sphincter is associated with two muscles which are the internal urethra sphincter which is a smooth muscles that is under involuntary control while the external urethra sphincter is a striated muscle that is under voluntary control.
14. Incontinence.
Incontinence refers to poor bladder control, there are many types of incontinence caused by various factors.

The correct answer is  b)