NSC 170C1 1st Edition Lecture 18 Outline of Last Lecture I Minerals Outline of Current Lecture II Importance of Water III Water balance IV Bottled vs Tap Current Lecture V Why is water so important A It is the most abundant substance in your body i The average healthy adult is about 60 percent water a Amount of body water depends on age gender and the amount of fat and muscle tissue you carry ii Muscle tissue is 65 percent water fat tissue is only 10 to 40 percent water iii Men have a higher percentage of muscle mass and therefore more body water than women B Water is essential for maintaining fluid balance i Electrolytes are minerals important in fluid balance a Include sodium potassium phosphate magnesium calcium and chloride ii Attract water into and out of your cells C Water Is the Universal Solvent i A solvent is a liquid in which a substance dissolves ii As a solvent water is part of the medium in which molecules come into contact with each other and allows chemical reactions to take place D Water Is a Transport Medium i Water is a major component of blood ii Water helps transport oxygen nutrients and other important substances to your cells iii Water transports waste products away from cells to be excreted in urine and stool a Lymph fluid is almost entirely water iv Transports proteins back to the bloodstream a Important in the absorption of fats v Transports wastes and microbes through lymph nodes where defensive cells consume the harmful substances E Water Helps Maintain Body Temperature i VI Water in your circulating blood absorbs heat from your internal core and carries it to the skin for release ii During exercise evaporation of sweat on your body releases heat to help cool you down and maintain a safe body temperature iii When you are cold less blood flows to your body surface in order to keep your internal organs at your body core warm F Water Is a Lubricant and a Protective Cushion i Combined with other molecules water acts as a lubricant for your joints ii As a component of tears it lubricates your eyes and flushes out dust and debris iii It is part of the saliva that moistens your mouth and foods and the mucus that lubricates your intestinal tract iv It is a central component of the fluid that surrounds your brain and protects it from injury during a fall or trauma v During pregnancy the watery amniotic fluid protects the fetus from any physical harm What Is Water Balance and How Do You Maintain It A You Take in Water through Beverages and Food B You Lose Water through Your Kidneys Large Intestine Lungs and Skin i Losing Too Much Water Can Cause Dehydration ii Other Ways to Tell if You Are Dehydrated iii Consuming Too Much Water Can Cause Hyponatremia C Water balance a state in which an equal amount of water is lost and replenished daily i Too much or too little water in your system can cause health problems ii Water is lost from the body in several ways and several mechanisms help you to replenish those losses iii You Take in Water through Beverages and Food iv Most of your daily water comes from beverages such as water milk juices and soft drinks v You get some water from the foods you eat though much less in comparison vi Even seemingly dry foods provide some water vii A small amount of water is also generated during metabolism D Water Intake and Water Output i ii You Lose Water through Your Kidneys Large Intestine Lungs and Skin You lose water daily through four routes a Your kidneys in the form of urine b Intestinal fluids in your stool c Water that evaporates when you exhale d Your skin when you release the heat produced in your body core e You Lose Water through Your Kidneys Large Intestine Lungs and Skin f Insensible water loss describes loss of water through evaporation of your breath and through your skin Doesn t include the water lost in sweat g The amount of water lost in sweat varies depending on environmental factors temperature weather clothing worn and the amount of physical activity you are doing III Dehydration A Dehydration is the state in which the body has too little water B It can result from i Not drinking enough fluid ii Water losses due to illness such as diarrhea vomiting or fever iii Use of diuretics such as alcohol and certain medications C If dehydration persists it can cause weight loss dizziness confusion inability to perform physical activity and in extreme cases death D Your Thirst Mechanism Signals Dehydration i The thirst mechanism includes various bodily reactions caused by dehydration that signal you to drink fluids ii Dry mouth is due to increased concentration of electrolytes in your blood which limits the water available to make saliva iii Increased concentration of electrolytes especially sodium in the blood is detected by the brain and triggers thirst iv The brain also signals the kidneys to remove less water from the blood and concentrate urine E Other Ways to Tell if You Are Dehydrated i Elderly people individuals who are physically active or have vigorous jobs or people experiencing fever diarrhea and or vomiting are at risk for dehydration ii Measuring body weight before and after physical activity is one way to monitor hydration status iii Urine color can also be used to assess hydration a What the Color of Your Urine Can Reveal b If you collect your urine in a cup and it looks like the color of 1 through 3 on the chart you are well hydrated F c If your urine resembles color 7 or is darker you are dehydrated and need to drink more fluids iv If you are physically active and the color of your urine darkens during the day you likely need to drink more Consuming Too Much Water Can Cause Hyponatremia i Overhydration can cause hyponatremia a low level of sodium in the blood which may result in dangerous swelling of the brain ii Symptoms of hyponatremia include fatigue confusion and disorientation which may be mistaken for dehydration iii The seriousness of overhydration has prompted the USA Track Field Association to revise its hydration guidelines for longdistance runners to avoid hyponatremia IV How Much Water Do You Need and What Are the Best Sources A Daily water requirement depends on physical activity environmental factors and diet B Women 12 cups of fluid daily 9 cups from beverages C Men 16 cups of fluid daily 13 cups from beverages D Caffeinated coffee tea and soft drinks do contribute to daily water needs i 20 percent of daily fluids can come from foods ii All foods contain water iii Cooked hot cereals fruits