Summary
The excretory system removes waste products from the body to maintain homeostasis.
- Excretion — the process of removing waste products from the body Example: The kidneys excrete urea and other waste products from the blood.
- Kidneys — organs that filter blood to produce urine Example: The kidneys remove excess salts and water from the bloodstream.
- Urea — a waste product formed in the liver from the breakdown of proteins Example: Urea is transported in the blood to the kidneys for excretion.
- Urine — liquid waste composed of water, urea, and other substances Example: Urine is stored in the bladder before being excreted from the body.
- Nephron — the functional unit of the kidney Example: Each nephron filters blood and forms urine.
Exam Tips
Key Definitions to Remember
- Excretion: the process of removing waste products from the body
- Kidneys: organs that filter blood to produce urine
- Urea: a waste product formed in the liver from the breakdown of proteins
Common Confusions
- Confusing excretion with egestion, which is the removal of undigested food
- Thinking that all waste products are excreted through urine
Typical Exam Questions
- What is the main function of the kidneys? To filter blood and produce urine.
- How is urea formed in the body? Urea is formed in the liver from the breakdown of proteins.
- What is the role of nephrons in the kidneys? Nephrons filter blood and form urine.
What Examiners Usually Test
- Understanding of the process of excretion
- The role and function of the kidneys and nephrons
- Differences between excretion and other processes like egestion