Kidneys & Control of Water Balance
Applied Science: BTEC Level 3 National Extended Diploma, topic 4.7.1
Water Balance
Water levels in the body must be kept relatively constant to control the amount of water and ions diffusing in and out of cells. Many factors can disrupt this balance.
Exhalation
- Water in the lungs leaves the body in the person’s breath.
Sweating
- Water, ions and urea are all lost in sweat.
Eating too much salt
- This can make the blood ion concentration too high.
Illness
- Illnesses that cause fever, vomiting or diarrhoea can result in dehydration (the blood's water concentration is too low).
Kidneys
The kidneys are important for homeostasis. They control the water and ion levels in the blood.
Ion levels
- The body's ion levels must be kept relatively constant to control osmosis and diffusion between cells in the body.
Excess water
- The volume of water in the blood is monitored by the hypothalamus in the brain.
Urea
Urea needs to be removed from the body because it is toxic. When there is too much urea in the bloodstream, it can harm cells and tissues.
Amino acids
- Urea is formed when the digestion of protein results in an excess of (too many) amino acids, which can't be stored in the body.
Deamination
- In the liver, these amino acids undergo a process known as deamination, and the waste product is ammonia.
Ammonia
- The ammonia is then converted into urea and must be excreted from the body as urine.
Test yourself on Kidneys & Control of Water Balance
Which part of your body monitors the volume of water in the blood?
Where does deamination take place?
Production of Urea