The male urinary system, or excretory system, consists of the kidneys, bladder, ureters, and urethra. The purpose of the male urinary system is to collect and excrete liquid waste from the body in the form of urine. The male urinary system differs slightly from the female urinary system because of the interconnection of the genitals.
The kidneys are located in the back part of the abdominal cavity just below the bottom ribs and above the lower back. There is one kidney on either side of the body. The kidneys are bean-shaped and roughly the size of an adult human fist.
The primary function of the kidneys is to sift waste material and excess water from the bloodstream. Inside the kidneys are tiny waste processing structures called nephrons, which are responsible for the production of urine. Inside the nephrons are tiny blood vessels called glomeruli, which act like filters that keep healthy blood components and flush out toxins and waste products.
Urine leaves the kidneys via two tubes called ureters. One ureter is located in the middle of both kidneys on the side of the organs that face the spine. They extend down the body and connect to the back of the bladder.
The bladder, or urinal bladder, collects and holds urine. It's an expandable, hollow, and muscular organ that sits on the pelvic floor, which is also called the pelvic diaphragm. In the male urinary system, the bladder lies between the rectum and the pubic symphysis, which is a cartilaginous joint that unites parts of the pubic bones.
The male urinary bladder sits above the prostate gland, which is a structure that's not present in females. In the female urinary system, the bladder sits below the uterus at the top of the vagina. The male bladder is larger and can hold a greater amount of urine than the female bladder.
Urine leaves the bladder via a muscular tube called the urethra. In the male urinary system, the urethra extends from the bladder to the end of the penis. In the female urinary system, the urethra extends from the bladder to an opening just above the orifice of the vaginal cavity. The male urethra serves as a pathway to both urine and semen and is considerably longer than the female urethra. Because of the greater length of the male urethra, it's divided into four parts for identification purposes: pre-prostatic urethra, prostatic urethra, membranous urethra, and spongy urethra.