Introduction: Water—The Body’s Vital Fluid
Welcome to the study notes on Water! While we often focus on nutrients like proteins or vitamins, water is just as essential for life. In fact, our bodies are made up of about 60% to 70% water! Without it, we wouldn’t last more than a few days. Don't worry if this seems like a lot to remember; we will break down why we need water, where we get it from, and why some days we need to drink more than others.
1. The Functions of Water in the Body
Think of water as the "oil" that keeps a machine running smoothly. It doesn't provide energy (calories), but it is involved in almost every process in our body.
Key Functions:
1. Acts as a Solvent: Water dissolves many nutrients (like Vitamin C and minerals) so they can be used by the body. Imagine trying to mix Milo powder without water—it stays as a powder! Water helps dissolve things so they can move around.
2. Transportation: It is the main part of blood. It acts like a "delivery truck," carrying nutrients and oxygen to cells and taking waste products (like carbon dioxide) away to be removed.
3. Temperature Regulation: When we get too hot, we sweat. As the water in sweat evaporates from our skin, it cools the body down. It's like our body's built-in air conditioner!
4. Lubrication: Water helps keep our joints "oiled" so we can move smoothly. It also keeps our eyes, nose, and mouth moist.
5. Removal of Waste: Water helps our kidneys filter out waste, which we then get rid of as urine.
Quick Review: Water is a solvent, a transporter, a coolant, and a lubricant.
2. Sources of Water in the Diet
We don't just get water from the tap! We get it from many different places in our diet.
Direct Sources:
Examples: Plain water, fruit juices, milk, and tea.
Food Sources:
Did you know many solid foods contain a lot of water?
- Fruits: Watermelon (it’s in the name!), oranges, and grapes.
- Vegetables: Cucumber, lettuce, and tomatoes.
- Prepared Foods: Soups, porridges, and jellies.
Did you know? A cucumber is actually about 95% water! Eating your vegetables is another way to stay hydrated.
3. Factors Affecting Water Intake
Most people are told to drink 8 glasses of water a day, but this isn't a "one size fits all" rule. Several factors change how much water you need to drink.
Use the mnemonic "H.A.D.E." to remember these factors:
H – Health (State of Health): If you have a fever, diarrhea, or vomiting, your body loses a lot of fluids. You need to drink extra water to replace what is lost.
A – Activity (Level of Activity): When you exercise or play sports, you sweat more. This means you need more water to prevent dehydration.
D – Diet:
- If you eat a lot of salty food, your body needs more water to balance the salt.
- If you eat a diet high in dietary fibre, you need more water to help the fibre move through your digestive system smoothly.
E – Environment: On a very hot or humid day in Singapore, you lose more water through sweat, even if you aren't exercising. You need to drink more to stay cool.
Takeaway: The hotter you are, the more active you are, or the saltier your food is, the more water you need!
4. Health Problems Related to Water
When our water "balance" is off, it can lead to serious health issues.
Dehydration
Dehydration happens when your body loses more water than it takes in.
Common signs: Feeling thirsty, dark-colored urine, headaches, and feeling dizzy or tired.
Heat Stroke
If dehydration gets very bad and the body can no longer cool itself down in a hot environment, heat stroke can occur. This is a medical emergency where the body temperature rises to dangerous levels.
Common Mistake to Avoid: Don't wait until you are thirsty to drink water! Thirst is actually a sign that your body is already starting to get dehydrated.
Summary Checklist
Can you do the following?
- List 3 functions of water? (e.g., transport, cooling, lubrication)
- Name 2 fruits or vegetables high in water? (e.g., watermelon, cucumber)
- Explain why an athlete needs more water than someone sitting in a classroom? (Level of activity/sweat)
- Define Dehydration? (Losing more water than you take in)
Keep up the great work! Water might seem simple, but it's the foundation of a healthy body.