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BIBLIOGRAPHY

Ureters, Bladder, Urethra

Ureters

 

Ureters connect the kidney to the bladder, and are the transportation system for urine. Ureters propel the urine using peristalsis

 

Peristalsis is the involuntary wave like muscle contractions. They push the urine down using the muscles lining the walls, and they work the same way the esophagus does. In adults the ureters are 25-35 cm long. It contains many layers in its walls. The outer layer is connective tissue. It is called the outer circular muscle. The next two layers are muscle. This is the inner logitudinal muscle. The next layer is another layer of connective tissue, called the submucosa.

The last layer is the outer wall of the lumen, called the urothelium. (tube urine passes through) Epithelial cells make up the wall of the lumen, and it is impermeable for obvious reasons.

 

Bladder

 

Bladder is where urine is stored before its released from the body. Urine enters the bladder from the kidneys, through the ureters. A bladder in an adult can hold over  2 cups before it needs to be emptied. There are two types of nerves that are active in the functioning of the bladder. Sensory nerves sense the fullness of the bladder. Motor nerves trigger the muscles of the external sphincter. The external sphincter is a muscle band at the exit of the bladder

It is controlled voluntarily to allow you to control when you want to urinate.

 

There are also muscles in the walls of the bladder that contract forcing urine out of the bladder. Urine exits the bladder through the urethra.

 

Urethra

 

The urethra is the final stage of the urinary tract. It excretes urine out of the body, from the bladder. It also has a urinary sphincter, which is the second stage of the urethra. In males the urethra is longer than in females.

males have three sections of the urethra, while females only have one part, which leads right out of the body

 

The first part is called the prostatic urethra, and it runs from the bladder to the part of the urethra where the vas deferens joins. The second part is the membranous urethra, and it’s the part that runs through the urinary sphincter. The third part is the spongy urethra which runs through the length of the penis, and it is stretchy, to allow for erections used in reproduction.

 

3pic.jpg

The Urinary Tract
 
This picture depicts the urinary tract. It clearly shows the ureters, (the tubes connecting the kidneys and the bladder), the bladder and the first section of the urethra. This urethra would simply exit the body in females, and would have 3 parts if it were a male's urethra.

How The Wastes Come Out