http://www.ck12.org Chapter 1. Human Biology
FIGURE 1.66
The kidneys filter the blood that passes through them, and the urinary
bladder stores the urine until it is released from the body.What is Urine?
Urineis a liquid that is formed by the kidneys when they filter wastes from the blood. Urine contains mostly water,
but it also contains salts and nitrogen-containing molecules. The amount of urine released from the body depends
on many things. Some of these include the amount of fluid and food a person consumes and how much fluid they
have lost from sweating and breathing. Urine ranges from colorless to dark yellow but is usually a pale yellow color.
Light yellow urine contains mostly water. The darker the urine, the less water it contains.
The urinary system also removes a type of waste calledureafrom your blood. Urea is a nitrogen-containing
molecule that is made when foods containing protein, such as meat, poultry, and certain vegetables, are broken
down in the body. Urea and other wastes are carried in the bloodstream to the kidneys, where they are removed and
form urine.
Vocabulary
- kidneys: Main organ of the excretory system; filters blood and forms urine.
- urea: Nitrogen-containing molecule made when foods containing protein are broken down in the body.
- ureters: Tube-like organs of the urinary system that move urine from the kidneys to the bladder.
- urethra: Tube-like organ of the urinary system that carries urine out of the body from the bladder; in males,
it also carries sperm out of the body. - urinary bladder: Hollow, balloon-shaped organ that stores urine.
- urinary system: Organ system that makes, stores, and gets rid of urine.
- urine: Liquid waste that is formed by the kidneys when they filter wastes from the blood.
Summary
- The urinary system is made up of the kidneys, the ureters, the bladder, and the urethra.
- Urine is the liquid that is formed by the kidneys when they filter wastes from the blood. Urine contains water,
salts, and nitrogen-containing molecules.
Practice
Use the resource below to answer the questions that follow.
- The Nephronat http://www.youtube.com/watch?v=aQZaNXNroVY (5:46)