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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07-Apr-11

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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07-Apr-11

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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07-Apr-11

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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07-Apr-11

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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07-Apr-11

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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07-Apr-11

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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07-Apr-11

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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