Importance of water balance in the body - Why do we need to maintain a constant internal environment? - GCSE Combined Science Revision - OCR 21st Century - BBC Bitesize (2024)

Importance of water balance in the body

Water content in the blood

is the control of water levels and mineral salts in the blood.

Water levels and mineral salts in the blood are controlled to protect animal cells by stopping too much water from entering or leaving them. The concentration of water and salts is the same inside and outside of the cells. If body cells lose or gain too much water by osmosis, they do not function efficiently.

If the concentration of water is the same inside and out the cells, then there is no movement of water into or out of the cell. The cells remain in their normal state.

If the water concentration is too high outside of the cell then water enters the cell by . If too much water enters, the cell will burst. If the water concentration is too low outside compared to the inside of the cells, water leaves the cells by osmosis. This causes cells to shrivel.

Human excretory organs

The organs of excretion in humans include the skin, lungs and kidneys.

Water is lost from the body as:

Skin

Sweat glands in the skin produce sweat. Water, and are lost from the skin as they are contained in sweat.

Lungs

Water and excess carbon dioxide leaves the body via the lungs when we .

We cannot control the level of water, ions or urea loss by the lungs or skin. For example, in a hot climate, your body sweats to help keep you cool. In the same way, when we breathe out we lose water vapour, and we cannot alter the amount we lose.

Kidneys

The kidneys are organs of the urinary system. The urinary system removes excess water, salts and urea.

Learn more about water and nitrogen balance with Dr Alex Lathbridge.