Water in the Body, Module 6, PDF

Water Chapter 10 1  Water Body is made up of 60% water Varies according to: Age (higher in children) M or F (higher in males) Lean body mass (higher in muscle – 70% water; fat 10% water)) bone density (higher in children and males)...

Water Chapter 10 1  Water Body is made up of 60% water Varies according to: Age (higher in children) M or F (higher in males) Lean body mass (higher in muscle – 70% water; fat 10% water)) bone density (higher in children and males) 2 Water in the Body 55% - intracellular fluid (water inside the cells) 45% - extracellular fluid (outside cells) 5% - bone, gallbladder (bile), glands, other fluids (spine, digestive, etc) Interstitial fluid consists of extracellular fluid, lymph, blood plasma The fluid pressure of blood against the blood vessels is blood pressure 3 Water in Foods Foods containing a high proportion of water have a low kcal content Examples …………… Foods containing a high proportion of fats have very little water - high kcal content Examples……………. 4 Functions of Water carries nutrients and waste products throughout the body transports vitamins and minerals acts as a lubricant and cushion (joints, eyes, amniotic fluid) assists in chewing, tasting and swallowing (saliva) maintains body temperature (sweating) maintains blood volume (blood is 90% water) needed for chemical reactions (hydrolysis, condensation, metabolism) 5 Absorption of Water Over 80% of ingested water is absorbed in the ______________ small amount absorbed in the: - stomach - LI (excretion) The longer the feces stays in the LI, the more water is absorbed back into the body (constipation) However, if you consume soluble fibre (eg. psyllium) it absorbs water in the LI and makes stools softer, therefore no constipation 6 Sources of Water Intake Eating (700 – 1000ml) Drinking (550 – 1900ml) Metabolism (200 – 300ml) Total 1450 – 3300ml (How many Litres?) DRI: AI – males 3.7 L/day - females 2.7 L/day 7  Regulation of Water Intake 1) Hypothalamus - Part of the brain stem - Regulates thirst - Directly monitor blood [ ] of water and solutes - When blood is too concentrated with solutes (not enough water), the hypothalamus initiates impulses that stimulate one to ingest fluids 2) Mouth (mouth gets dry and you drink more water) 3) Stomach - nerves in the stomach act as stretch receptors - when the stretch receptors are stimulated enough, we stop drinking fluids *Thirst lags behind water lack* You can get dehydrated before you realize it  Dehydration – loss of fluid in the body 8 Regulation of Water Intake The sensation of Thirst helps motivate fluid intake to restore water balance. 9 How do you know if you are dehydrated? Simple Test The darker an individual’s urine colour, the greater the level of dehydration. Pale yellow urine indicates good hydration. Symptoms Thirst, muscle cramps, fatigue, dizziness, fainting 10  Who Should Increase Their Water Intake? Athletes (sweating) Working/exercising in heat/humidity (sweating) Elderly ( sensitivity to thirst) Lactating women (lack of fluids can stop milk production) Infants (cells are increasing in size therefore need more water) High protein diet (excretion of NH2) Fever (sweat) Diuretics ( urination) - tea, coffee, alcohol, medications Diarrhea/vomiting (loss of fluids) High salt in diet (need more water to excrete salt) 11  How the Body Regulates Blood Volume (water excretion) Kidneys Brain The kidneys respond to The hypothalamus responds reduced blood flow by to high salt concentrations releasing the enzyme in the blood by stimulating renin. the pituitary gland. Renin Renin initiates the The pituitary gland activation of the protein releases antidiuretic angiotensinogen to hormone (ADH). angiotensin. Angiotensin Angiotensin signals Angiotensin causes the adrenal gland the blood vessels ADH to secrete to constrict, raising aldosterone. pressure. Aldosterone Aldosterone and ADH signal the kidneys to retain sodium and water, respectively, thus increasing blood volume. ( water excretion)  Water Excretion Kidneys (500 – 1500 ml) Feces (100 - 200 ml) Lungs (250 - 400 ml) Skin (600 – 1200 ml) Total 1450 – 3300ml/day (Litres……….) Water ingestion = water excretion 13  Water Balance: Average Water Intake and Output (non-exerciser) Copyright 2012, John Wiley & Sons Canada, Ltd. 14  Water Intoxication (excess intake) A condition in which body water contents are too high may occur if: i) drink water for a prolonged period, faster than the kidneys can excrete excess ii) administer pure water to a dehydrated person (no electrolytes) When a person doesn’t have enough electrolytes, they MAY experience a salt craving 15 Water Intoxication (excess intake) Symptoms (related to a decrease in electrolytes, esp Na) swelling of cells (edema) muscle cramps convulsions Confusion See next slide regarding newspaper article on water intoxication 16 Newspaper Article: Man intoxicated on water - A 29 year old man who drank 50 bottles of water in 3 hours and then drank more water from a garden hose was rushed to hospital suffering from water intoxication - The man’s mother called police to the home - When police arrived, the man was ‘incoherent and exhibiting paranoid behaviour’ He was still drinking from the garden hose!! - Police did not know exactly how many litres of water the man consumed - He suffered a seizure on the way to the hospital and was transferred to the critical care unit - Police don’t know why the man was bingeing on water - Experts say that excessive water consumption can cause a heart attack or organ failure - The American Journal of Psychiatry says self-induced water intoxication sometimes occurs in schizophrenic patients. 17 Electrolyte Balance Electrolyte - a substance that ionizes in water solution (+ve or -ve) (NaCl) water dissolves salts and follows electrolytes Electrolyte Balance: condition that exists when the quantities of electrolytes enteirng the body equal those leaving it 18 Electrolyte Balance (cont’d) Acid - electrolytes that release hydrogen ions (HCl H+ + Cl-) Base - compounds that accept H ions in a solution; OH ions predominate (NaOH Na+ + OH-) Base: Example - lye: a solution of wood ashes and water (used to make soap) 19 The pH Scale (a measure of the [ ] of H ions) The lower the pH, the higher the [ ] of H ions, and the stronger the acid 20 Electrolyte Balance (cont’d) Solutes - substances that are dissolved in a solution salt - substances formed by the reaction between an acid and a base (HCL + NaOH H20 + NaCl) anion - negatively charged ion cation - positively charged ion 21  Important Electrolytes in the Body Na is the main extracellular cation K is the main intracellular cation Chloride 22  Water dissolves salts and follows electrolytes Cl - + Na+ H O H + Na+ Cl - The structural arrangement of the two hydrogen atoms and one oxygen atom enables water to dissolve salts. Water’s role as a solvent is one of its most valuable characteristics. Osmotic Pressure: the tendency for water to follow electrolytes  Osmosis 1 With equal numbers of solute 2 Now additional solute is 3 Water can flow both ways particles on both sides, the added to side B. Solute cannot across the divider, but has a concentrations are equal, flow across the divider (in the greater tendency to move from and the tendency of water to case of a cell, its membrane).23 side A to side B, where there move in either direction is is a greater concentration of about the same. solute. The volume of water becomes greater on side B, Water seeks to dilute solute [ ] by moving from an area of and the concentrations on side A and B become equal. low [ ] to high [ ] This maintains the electrolyte balance in the cells of the body The movement of water across a membrane toward the more concentrated solutes is called osmosis When sprinkled with salt, vegetables “sweat” because water moves toward the higher concentration of salt outside the eggplant. When immersed in water, raisins get plump because water moves toward the higher concentration of sugar inside the raisins. Osmosis and distribution of water in the body 27 Water and/or Electrolytes for Exercise 28  Recommended Fluid Intake During Exercise Copyright 2012, John Wiley & Sons Canada, Ltd.  Water vs electrolytes for exercise During exercise: Excreting water (sweat) - each one litre of sweat contains about 1.5 grams of salt 30 Electrolytes and Exercise Exercise one hour or less: water only Exercise 1 hour or more water and a CHO solution (6 – 8%)  may also need electrolytes if: - it is very hot/humid - higher intensity and longer duration - need a salty beverage if “salts can be seen on clothing after sweating” - Need to dilute both CHO and sodium - Example: marathon runner gained 10 lbs due to high consumption of electrolytes and not enough water - GATORADE developed by …………………………………………….. 31 Electrolytes and Exercise Recommendation The average Canadian consumes sufficient or too much sodium in their diet, therefore, normal dietary intake of sodium can replace losses during exercise. Therefore, no need for “Gatorade” or “Powerade”, “Thirstade”, (unless exercising in a hot/humid environment) Ingesting a “normal” diet may be sufficient for electrolyte replacement during exercise 32 Bottled Water Health Canada defines bottled water as water intended for human consumption that is packed in a sealed container. It can be derived from natural sources such as springs or from municipal water supplies. 33  About 22% of Canadian households use bottled water as their main drinking source 50% of households use some sort of filtration system for their tap water. 70% choose bottled water because of taste and odor 25% perceive bottled water as safer and healthier. Is bottled water better nutritionally? Unless there are concerns about the safety of your tap water, it is best to choose tap water (fortified with fluoride if possible) 34