4.7.1

Kidneys & Control of Water Balance

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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

Exhalation

  • Water in the lungs leaves the body in the person’s breath.
Sweating

Sweating

  • Water, ions and urea are all lost in sweat.
Eating too much salt

Eating too much salt

  • This can make the blood ion concentration too high.
Illness

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

Ion levels

  • The body's ion levels must be kept relatively constant to control osmosis and diffusion between cells in the body.
Excess water

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

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

Deamination

  • In the liver, these amino acids undergo a process known as deamination, and the waste product is ammonia.
Ammonia

Ammonia

  • The ammonia is then converted into urea and must be excreted from the body as urine.
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1

Principles of Science I

1.1

Structure & Bonding

1.2

Properties of Substances

1.3

Cell Structure & Function

1.4

Cell Specialisation

1.5

Tissue Structure & Function

1.6

Working with Waves

1.7

Waves in Communication

2

Practical Scientific Procedures and Techniques

3

Science Investigation Skills

4

Principles of Science II

4.1

Extracting Elements

4.2

Relating Properties to use of Substances

4.3

Organic Chemistry

4.4

Energy Changes in Industry

4.5

The Circulatory System

4.6

Ventilation & Gas Exchange

4.7

Urinary System

4.8

Cell Transport

4.9

Thermal Physics

4.10

Materials

4.11

Fluids

5

Contemporary Issues in Science

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    Production of UreaPut in order
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