07-Apr-11
Fluids Fluids
Body Fluids Electrolyte Balance
– Substances composed of freely moving molecules – Have the ability to conform to the shape of their container
There are different types of fluids in our bodies.
Fluids
Fluids
• 50 – 70% of a healthy adult’s body is composed of fluids • About 2/3 of this fluid is within body cells and is called intracellular fluid • The remaining 1/3 is extracellular fluid
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07-Apr-11
Fluids
Fluids • Extracellular fluids include – Tissue fluid found between the cells within tissues and organs of the body – Plasma, Pl the h fl fluid id portion i off blood bl d that carries the blood cells
Fluids The body fluid composition of tissue varies by – Tissue type – lean tissues have higher fluid content than fat tissues – Gender – males have more lean tissue and therefore more body fluid – Age – lean tissue is lost with age and body fluid is lost with it
Electrolytes Body fluid is composed of – Water – Electrolytes: mineral salts dissolved in water, including: • Sodium • Potassium • Chloride • Phosphorus
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Electrolytes
Electrolytes
• Electrolytes carry electrical charges:
• Fluids have an overall neutral charge due to the balances between electrolytes
– Sodium (Na+) and potassium (K+) are positively charged – Chloride (Cl-) and phosphorus (as 2 , phosphate) HPO O42h h ) are negatively i l charged
Functions of Fluids Fluids dissolve and transport substances – Water is an excellent solvent because it can dissolve many different substances – The dissolved materials, or solutes, i l d ions, include i sugars, amino i acids, id vitamins, and minerals
• In intracellular fluid, K+ and HPO42- are the predominant electrolytes • In extracellular fluid, Na+ and Clpredominate
Functions of Fluids Fluids account for blood volume. – Blood volume is the amount of fluid in the blood – Increased blood volume can cause blood pressure to rise – Decreased blood volumes can cause low blood pressure
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Functions of Fluids
Functions of Fluids
Fluids help maintain body temperature. – The high heat capacity of water means that the temperature of our body fluids remains quite stable – Sweating releases heat as the evaporation of water from the skin cools the skin and blood
Functions of Fluids Fluids protect and lubricate body tissues. – Cerebrospinal fluid protects the brain and spinal column – Amniotic fluid protects the fetus – Synovial y fluid is a lubricant around joints – Digestive secretions allow for easy passage of material
Functions of Electrolytes Electrolytes help regulate fluid balance. – Water follows the movement of electrolytes, moving by osmosis to areas where the concentration of electrolytes is high g – This allows for the controlled movement of fluids into and out of cells
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Functions of Electrolytes: Osmosis
Functions of Electrolytes Electrolytes help nerves respond to stimuli. – Movement of Na+ and K+ across the membranes of nerve cells changes the electrical charge across the membrane – This change in electrical charge carries the nerve impulse along the nerve cell
Functions of Electrolytes Electrolytes signal our muscles to contract. – The movement of calcium (Ca2+) into a muscle cell stimulates the muscle to contract – The Ca2+ is pumped back out of the cell after the muscle contraction
Maintaining Fluid Balance • Any water lost from the body must be replaced • Water is gained through beverages, food, and metabolic reactions • Water is lost through urine urine, sweat, sweat exhalation, and feces
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Water Balance Water Intake
Amount (mL)
Liquids
550 - 1500 Kidney
500 - 1400
Foods
700 - 1000 Skin
450 - 900
Metabolic 200 - 300
Total
1450 - 2800
Water Removal
Maintaining Fluid Balance Amount (mL)
Lungs
350
GI tract
150
• Loss of water – Most water is lost through urine – The kidneys control how much water is reabsorbed. Excess water is processed by the kidneys and excreted as urine – Insensible I ibl water t is i lost l t through th h the th skin ki (sweat) or through the lungs during exhalation
1450 - 2800
Maintaining Water Balance
Functions of Water
• Taking in water – Most water enters the body through beverages – Some foods have very high water contents • Manyy fruits and vegetables g are > 90% water – Metabolic water is a product of many chemical reactions in the body and contributes 10-14% of the body’s needs
Essential For Life
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Maintaining Fluid Balance • Functions of water
Water • What if you drink too much water?
– Essential for life – Required for fluid and electrolyte balance and many metabolic reactions
• Recommendation for water
– Becoming over hydrated is rare – Can result in a dilution of sodium leading to hyponatremia, a life-threatening condition
• What if you don’t drink enough water? – Dehydration h d i – Infants and the elderly are especially vulnerable
– Varies with climate, activity and body size – Recommendation for adult men is 3.7 litres/day – Recommendation for adult women is 2.7 litres/day
Water in Foods
Water in Foods
100%
Water, Club Soda
60 – 69%
90 – 99%
Fat Free Milk; strawberries, watermelon; lettuce, celery, spinach Fruit juice; yogurt; apples; grapes; carrots; most fruits Shrimp; bananas; corn; potatoes, avocado; cottage and ricotta cheese Ground beef; hot dog; feta cheese
40 - 49%
Pasta; legumes; salmon; ice cream; chicken breast Pizza
30 - 39%
Cheddar cheese, bagels; bread
20 - 29%
Pepperoni sausage; cake; biscuits
10 - 19%
Butter; margarine; raisins
1 – 9%
Crackers; cereals; pretzels; taco shell; peanut butter, nuts Oils
80 – 89% 70 - 79% 50 – 59%
0%
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Sodium • Functions of sodium – Fluid and electrolyte balance – Associated with blood pressure and pH balance in the body – Required for nerve impulse transmission – Assists in the transport of certain nutrients (eg., glucose) into body cells
Sodium Sodium content of foods – Many high sodium foods can be replaced by a lower sodium alternative:
Dill pickle (1731 mg) low sodium pickle (23 mg) Cured ham (1023 mg) pork roast (54 mg) Canned soup (695 mg) low sodium soup (480 mg) Potato chips (168 mg) baked potato (14 mg)
Sodium • Recommended intake – Adequate Intake is 1.5 g/day (1500 mg/day) – Upper level is 2.3 g/day (2300 mg/day)
• Sodium intakes – Most sodium is consumed as sodium chloride and Canadians consume an average of 3092 mg sodium daily; 77 % is from processed foods – At least 75% of Canadians consume above the UL
Sodium • What if you consume too much sodium? – Hypernatremia is abnormally high blood sodium concentration – Can happen to patients with congestive heart failure or kidney disease – Results in high blood volume, edema, and high blood pressure
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Sodium • What if you don’t consume enough sodium? – Hyponatremia is an abnormally low blood sodium level – Can result from prolonged vomiting, diarrhea, or sweating – Has been seen in marathon athletes who consume too much water
Potassium • Recommended intake – Adequate intake is 4.7 mg/day (4700 mg/day)
• Sources of potassium – Processed foods are usually low in potassium – Fresh fruit and vegetables and whole grains are good sources of potassium
Potassium • Functions of potassium – Fluid and electrolyte balance – Very important in muscle contractions and transmission of nerve impulses – High g ppotassium intake helps p to maintain a lower blood pressure
Potassium • What if you consume too much potassium? – Hyperkalemia is a high blood potassium level – Can occur in patients with kidney disease – Can alter normal heart rhythm resulting in a heart attack
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Potassium • What if you don’t consume enough potassium? – Hypokalemia is low blood potassium levels – Can be seen in patients with kidney disease or diabetic acidosis – Can occur when taking certain diuretic medications
Chloride What if you consume too much chloride? – May lead to hypertension in salt-sensitive patients – No DRI has been set for chloride
What if you don don’tt consume enough chloride? – This is rare but can occur in people with eating disorders
Chloride • Functions of chloride – Assists with maintaining fluid balance – Assists the immune system – Part of hydrochloric acid in the stomach
• Recommended intake – Adequate intake is 2.3 g/day (2300 mg/day) – Almost all chloride is consumed as NaCl
Medical Disorders Disorders related to fluid and electrolyte imbalance include: – Dehydration – Heat stroke – Water intoxication – Hypertension – Muscle disorders
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Dehydration Dehydration occurs when water loss exceeds water intake • Commonly due to heavy exercise or high environmental temperatures. • Infants and the elderly are more at risk
Hypertension Hypertension is a chronic condition characterized by high blood pressure – Systolic pressure over 140 mm Hg – Diastolic pressure over 90 mm Hg – May not show symptoms – Increases a person’s risk of heart disease, stroke, kidney disease
Heat Stroke Heat stroke occurs if the body’s temperature regulation mechanisms fail – Occurs in hot, humid environments – Symptoms include rapid pulse, hot, dry skin, high body temp, weakness – Has been fatal for athletes during exercise in extreme heat
Muscle Disorders • Electrolyte imbalances can result in seizures or muscle cramps • Electrolyte imbalances cause changes in nervous system function • N Nervous system t changes h can alter lt proper muscle function
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Hypertension Does high sodium intake cause hypertension? – Most health organizations recommend a reduced sodium intake – Other ways to reduce blood pressure include: • Maintain healthy body weight • Increase physical activity • Reduce stress
Functions of Electrolytes Fluid and electrolyte balance
Phosphorus Functions of phosphorus – The major intracellular negatively charged electrolyte is HPO42– Required for fluid balance – Critical role in bone formation – Regulates biochemical pathways by activating or deactivating enzymes – Found in ATP, DNA, RNA
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Phosphorus Recommended intake – RDA for phosphorus is 700 mg/day
Sources of phosphorus – Widespread in many foods – Found in high amounts in foods that contain protein (e.g., meat, milk, eggs)
Phosphorus What if you consume too much phosphorus? – High blood phosphorus can occur with kidney disease, after taking too many vitamin D supplements, or over consuming phosphorus-containing antacids – Causes C muscle l spasms, convulsions li
Phosphorus What if you don’t consume enough phosphorus? – Deficiencies of phosphorus are rare – Those at risk are premature infants, elderly people consuming poor diets, or people who abuse alcohol
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