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
- 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.
1Principles of Science I
1.1Structure & Bonding
1.1.1Atomic Model1.1.2Electron Shells, Sub-Shells & Orbitals1.1.3Ionic Bonding1.1.4Representing Ionic Bonds1.1.5Covalent Bonding1.1.6Representing Covalent Bonds1.1.7Metallic Bonding1.1.8Intermolecular Forces1.1.9Intermolecular Forces 21.1.10End of Topic Test - Bonding1.1.11Relative Masses1.1.12The Mole1.1.13Molar Calculations1.1.14Molar Calculations 21.1.15Empirical & Molecular Formulae1.1.16Balanced Equations1.1.17Percentage Yield1.1.18End of Topic Test - Amount of Substance
1.2Properties of Substances
1.2.1The Periodic Table1.2.2Ionisation Energy1.2.3Factors Affecting Ionisation Energies1.2.4Trends of Ionisation1.2.5Trends in the Periodic Table1.2.6Polarity1.2.7Metals & Non-Metals1.2.8Alkali Metals1.2.9Alkaline Earth Metals1.2.10Reactivity of Alkaline Earth Metals1.2.11Redox1.2.12Transition Metals1.2.13Redox Reactions of Transition Metals
1.3Cell Structure & Function
1.4Cell Specialisation
1.5Tissue Structure & Function
1.5.1Human Gas Exchange1.5.2Blood Vessels1.5.3Atherosclerosis1.5.4Skeletal Muscle1.5.5Slow & Fast Twitch Fibres1.5.6Neurones1.5.7Speed of Transmission1.5.8Action Potentials1.5.9End of Topic Test - Neurones & Action Potentials1.5.10Synapses1.5.11Types of Synapse1.5.12Medical Application1.5.13End of Topic Test - Synapses1.5.14Chemical Brain Imbalances1.5.15Effect of Drugs on the Brain
1.6Working with Waves
1.7Waves in Communication
2Practical Scientific Procedures and Techniques
3Science Investigation Skills
3.1Scientific Processes
3.2Data Handling & Analysis
3.3Enzymes in Action
3.4Diffusion
3.5Plants & Their Environment
3.6Energy Content in Fuels
4Principles of Science II
4.1Extracting Elements
4.2Relating Properties to use of Substances
4.3Organic Chemistry
4.4Energy Changes in Industry
4.5The Circulatory System
4.5.1The Circulatory System4.5.2Blood Vessels4.5.3Blood Transfusion & the ABO Rhesus System4.5.4The Heart4.5.5The Cardiac Cycle4.5.6Cardiac Output4.5.7Coordination of Heart Action4.5.8Heart Dissection4.5.9Controlling Heart Rate4.5.10Electrocardiograms4.5.11Cardiovascular Disease4.5.12Investigating Heart Rates
4.6Ventilation & Gas Exchange
4.7Urinary System
4.9Thermal Physics
4.9.1Power & Efficiency4.9.2Work & Energy4.9.3Conservation of Energy4.9.4Pressure4.9.5First Law of Thermodynamics4.9.6Second Law of Thermodynamics4.9.7Heat Engines, Heat Pumps & Refrigerators4.9.8Non-Flow Processes4.9.9p-V Diagrams4.9.10Ideal Gases4.9.11Ideal Gases 24.9.12Thermal Energy Transfer4.9.13Thermal Energy Transfer Experiments
4.10Materials
5Contemporary Issues in Science
5.1Contemporary Issues in Science
5.2Analysing Scientific Information
Jump to other topics
1Principles of Science I
1.1Structure & Bonding
1.1.1Atomic Model1.1.2Electron Shells, Sub-Shells & Orbitals1.1.3Ionic Bonding1.1.4Representing Ionic Bonds1.1.5Covalent Bonding1.1.6Representing Covalent Bonds1.1.7Metallic Bonding1.1.8Intermolecular Forces1.1.9Intermolecular Forces 21.1.10End of Topic Test - Bonding1.1.11Relative Masses1.1.12The Mole1.1.13Molar Calculations1.1.14Molar Calculations 21.1.15Empirical & Molecular Formulae1.1.16Balanced Equations1.1.17Percentage Yield1.1.18End of Topic Test - Amount of Substance
1.2Properties of Substances
1.2.1The Periodic Table1.2.2Ionisation Energy1.2.3Factors Affecting Ionisation Energies1.2.4Trends of Ionisation1.2.5Trends in the Periodic Table1.2.6Polarity1.2.7Metals & Non-Metals1.2.8Alkali Metals1.2.9Alkaline Earth Metals1.2.10Reactivity of Alkaline Earth Metals1.2.11Redox1.2.12Transition Metals1.2.13Redox Reactions of Transition Metals
1.3Cell Structure & Function
1.4Cell Specialisation
1.5Tissue Structure & Function
1.5.1Human Gas Exchange1.5.2Blood Vessels1.5.3Atherosclerosis1.5.4Skeletal Muscle1.5.5Slow & Fast Twitch Fibres1.5.6Neurones1.5.7Speed of Transmission1.5.8Action Potentials1.5.9End of Topic Test - Neurones & Action Potentials1.5.10Synapses1.5.11Types of Synapse1.5.12Medical Application1.5.13End of Topic Test - Synapses1.5.14Chemical Brain Imbalances1.5.15Effect of Drugs on the Brain
1.6Working with Waves
1.7Waves in Communication
2Practical Scientific Procedures and Techniques
3Science Investigation Skills
3.1Scientific Processes
3.2Data Handling & Analysis
3.3Enzymes in Action
3.4Diffusion
3.5Plants & Their Environment
3.6Energy Content in Fuels
4Principles of Science II
4.1Extracting Elements
4.2Relating Properties to use of Substances
4.3Organic Chemistry
4.4Energy Changes in Industry
4.5The Circulatory System
4.5.1The Circulatory System4.5.2Blood Vessels4.5.3Blood Transfusion & the ABO Rhesus System4.5.4The Heart4.5.5The Cardiac Cycle4.5.6Cardiac Output4.5.7Coordination of Heart Action4.5.8Heart Dissection4.5.9Controlling Heart Rate4.5.10Electrocardiograms4.5.11Cardiovascular Disease4.5.12Investigating Heart Rates
4.6Ventilation & Gas Exchange
4.7Urinary System
4.9Thermal Physics
4.9.1Power & Efficiency4.9.2Work & Energy4.9.3Conservation of Energy4.9.4Pressure4.9.5First Law of Thermodynamics4.9.6Second Law of Thermodynamics4.9.7Heat Engines, Heat Pumps & Refrigerators4.9.8Non-Flow Processes4.9.9p-V Diagrams4.9.10Ideal Gases4.9.11Ideal Gases 24.9.12Thermal Energy Transfer4.9.13Thermal Energy Transfer Experiments
4.10Materials
5Contemporary Issues in Science
5.1Contemporary Issues in Science
5.2Analysing Scientific Information
Practice questions on Kidneys & Control of Water Balance
Can you answer these? Test yourself with free interactive practice on Seneca — used by over 10 million students.
- 1
- 2The kidneys control:True / false
- 3Where does deamination take place?Multiple choice
- 4Urea is excreted from the body. Urea is also:True / false
- 5Production of UreaPut in order
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