19 terms

Section 3: The Excretory System

Human Biology & Health (Sec. 3)
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excretory system
- system in the body that collects wastes produced by cells and removes the wastes from the body.
body must eliminate
- excess water
- urea
urea (yoo ree uh)
- a chemical that comes from the breakdown of proteins.
structures of the excretory system
- kidneys
- ureters
- urinary bladder
- urethra
kidneys
- majors organs of the excretory system that remove urea and other wastes from the blood.
- act like filters; remove wastes but keep materials that the body needs.
- there are two of them.
urine
- watery fluid that contains urea and other wastes.
ureters (yoo ree turz)
- two narrow tubes connecting the kidneys to the urinary bladder.
urinary bladder
- saclike muscular organ that stores urine.
urethra (yoo ree thruh)
- small tube through which urine leaves the body.
nephrons
- small filtering structure found in the kidneys that removes wastes from blood and produces urine.
stages to filter wastes by the nephrons
- 1st: both wastes and needed materials, such as glucose, are filtered out of the blood.
- 2nd: much of the needed material is returned to the blood.
-3rd: wastes are eliminated from the body.
why eliminate?
- eliminating wastes, such as urea, excess water, and carbon dioxide, is important for maintaining homeostasis.
excretion maintains homeostasis by
- keeping the body's internal environment stable and free of harmful levels of chemicals.
organs of excretion for homeostasis
- kidneys: regulate the amount of water in your body.
- lungs: exhalation of carbon dioxide and some water.
- skin: water and urea are excreted in perspiration.
- liver: breaks down proteins into urea and converts part of the hemoglobin molecule from old red blood cells into a bile. (acts like a recycling facility).
excretion
- the process of removing wastes from the body
- helps keep the body's internal environment stable and free of harmful materials
How do kidneys filter wastes from the blood?
- wastes filtered through nephrons
- blood enters the kidneys through arteries until it reaches a cluster of capillaries
- urea, glucose, and some water move out of the blood into the capsules
- blood cells and most protein molecules do not move into the capsule, but remain in the capillaries
What is the major organ of the excretory system?
the kidneys
What can glucose in urine mean?
You could have diabetes.
What can protein in the urine mean?
kidneys may have a problem