Human Nutrition 1 - Lesson 8

Topics: Dehydration, Water, Urine Pages: 6 (1552 words) Published: October 22, 2013

1. Explain in 2-3 sentences each, the role of water in the body for 5 different physiological processes.
Fluid intake and fluid excretion: There is usually a balance between intake and excretion of water. If the water balance becomes unbalanced, this can greatly affect various bodily functions such as blood pressure, blood sugar levels or brain function. This imbalance will also create a thirst reaction and by the time we perceive this, our body is already mildly dehydrated.

Water as a means of transport: Most of the water, which a person takes in each day, is required to transport nutrients into the cells. To be able to bind and remove metabolic waste products it is important that the water is not saturated with minerals. • Water for excretion, cleansing and detoxification: Water ensures that harmful catabolic products are washed from our bodies and detoxification processes can run more smoothly. In the cells it has a purifying action and is responsible for eliminating waste products and other residue. • Water as solvent: In our bodies water acts as a solvent for our food so that this can be transported and processed. It also serves to dilute a number of harmful substances. • Thermal regulation – the skin as air conditioning: An additional important role of water is to regulate body temperature. Alongside other regulatory mechanisms, sweating also helps maintain body temperature constant at around 37°C, regardless how cold or warm it is outside the body. •Regulation of the acid-base balance: Chemical processes are continually taking place in the body. Metabolism, muscular action, nerve transmission processes – these would all be impossible without these chemical processes. Acids and alkaline substances must be balanced. If this is not the case, this leads to an adverse metabolic condition for the body.

2. List 5 factors which affect the body’s requirement for water.

For the body to function, the absolute minimum amount of water recommended is 0.75l per day. However, there are many variations that affect the body’s requirement of water and the amount. •Climate

Physical activity
State of health
Body size

Under typical circumstances, adults may replenish an average of up to six or eight cups of fluid each day or around 2L. Water losses in urine account for about three-fourths of daily losses. Remaining losses come from sweat, as tiny water droplets in the air we exhale, and through faeces. Infrequent urination or dark yellow urine may indicate you could use more fluid intake each day.

3. In 200-300 words compare 3 different methods of purifying water, including two commercially available water purifiers. Consider how each method differs, and the advantages and disadvantages of each. Which one would you select to purify tap water in your house? Why?

1. Boiling Water
Boiling water (100 deg C) is a very effective and reliable method of disinfection. Bacteria and Viruses will die within seconds of reaching boiling point whilst Protozoa take 2 mins at 60 deg C to die. A reliable method, but you have to wait until the water cools before drinking it.

2. Chlorine Dioxide
Another method is using an electric current through a salty solution to create mixed oxidants of free chlorine, chlorine dioxide and ozone. The oxidants are then added to the water. Reported times for disinfection include 15mins for viruses and bacteria; 30mins for Giardia and 4 hours for Cryptosporidia. There are also liquid and tablet formulations containing only chlorine dioxide with/without an ‘activator’ eg. Phosphoric acid (Aquamira) which are mixed together before being added to water. These have also been shown to be effective against Cryptosporidium though times are very variable with turbidity and temperature (30-240mins).

3. Filters
There is no such thing as a whole house filter, as you will have utility water and drinking water. Whole house...
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