Excretion - introduction
Definition:
Excretion is the removal of waste products made by cells and extra substances that the body does not need.
Importance:
Excretion is important because it removes toxic metabolic waste products and excess substances from the body, helping maintain a stable environment.
Main reasons:
• Removes toxic waste products - Prevents harmful substances, such as carbon dioxide and urea, from building up and damaging cells.
• Maintains water balance - The kidneys remove extra water when there is too much water Srm conserve water earn there is too little, keeping the body’s water level stable.
• Maintaining salts balance - The kidney removes excess mineral ions, such as sodium, keeping ion levels within the normal range needed for cells to function properly.
• Helps control PH levels in blood - thé lungs remove carbon dioxide, preventing the blood from becoming too acidic and allowing enzymes to work efficiently.
• Maintains homeostasis - By regulating water, mineral ions and waste products, excretion keeps the internal environment stable do cells can function normally.
Homeostasis
Definition:
Homeostasis is the maintenance of a stable internal environment despite changes inside or outside the body.
Explanation:
The body works best when conditions inside it stay within a narrow range. Homeostasis keeps these conditions stable so cells and enzymes can function properly.
It regulates factors such as:
Body temperature
Water content
Blood glucose concentration
Mineral ion concentration
Blood pH
Example: If you sweat on a hot day, your body loses heat, helping keep your body temperature close to normal.
Metabolism waste
Definition:
Metabolism is the sum of all the chemical reactions that occur in living cells.
Explanation:
Every cell carries out thousands of chemical reactions to stay alive. These reactions:
Release energy (e.g. respiration).
Build larger molecules (e.g. making proteins).
Break down substances (e.g. digesting nutrients or breaking down excess amino acids).
Some metabolic reactions produce waste products, such as:
Carbon dioxide (from respiration).
Urea (formed in the liver after excess amino acids are broken down).
These waste products must be removed by excretion.
Connection between the two
Metabolism produces the waste products.
Excretion removes those waste products.
This helps maintain homeostasis, keeping the body’s internal environment stable.