Nutrients Involved in Fluid and Electrolyte Balance

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Nutrients Involved in Fluid and Electrolyte
Balance
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Body Fluids

• Body fluid is the liquid portion of cells and
  tissues
• Characterized by its ability to move freely and
  changeably, adapting to the shape of the
  container that holds it
• About 50-70 of healthy adult body weight

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Body Fluids

• Intracelluar fluid within the cell
• 2/3 of body fluid
• Extracellular fluid outside the cell
• 1/3 of body fluid
• Interstitial fluid flows between cells that make
  up a particular tissue or organ (muscle, liver)
• Intravascular fluid is the water in the blood and
  lymph
• Plasma transports blood cells within arteries,
  veins, and capillaries

Intracellular and Extracellular Fluid
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Body Fluids

• 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 than females
• Age decrease in body water results partly from
  loss of lean tissue as people age

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Electrolytes

• Dissolved substances that disassociate in
  solution into electrically charged particles
  called ions
• Positive charge sodium, potassium
• Negative charge chloride, phosphorus
• Predominant electrolytes
• Extracellular fluid potassium, phosphorus
• Intracellular fluid sodium, chloride

Role of Electrolytes in Water Balance
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Functions of Body Fluids

• Fluids dissolve and transport substances
• Water is an excellent solvent because it
  dissolves a variety of substances
• Water-soluble substances are readily transported
  in the bloodstream amino acids, glucose,
  vitamins, minerals, medications
• Fatty substances must be attached to or
  surrounded by water-soluble proteins

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Functions of Body Fluids

• Fluids account for blood volume
• Appropriate body fluid levels are essential for
  maintaining healthful blood volume
• Blood pressure increases when blood volume rises
• High blood pressure (hypertension) is a risk
  factor for heart disease and stroke
• Low blood pressure can cause people to feel
  tired, confused, or dizzy
• Kidneys help to regulate blood volume and blood
  pressure

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Functions of Body Fluids

• Fluids account for blood volume
• Antidiuretic hormone (ADH) stimulates the kidneys
  to reabsorb water, reducing urine
• Renin responds to decreased blood pressure
• Angiotensin II (vasoconstrictor) increases blood
  pressure
• Aldosterone signals the kidneys to retain sodium
  and chloride, thereby retaining water, increasing
  blood pressure, and decreasing urine output

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Functions of Body Fluids

• Fluids help maintain body temperature
• Body temperature must be within a safe range
• Water has a high capacity for heat, which means
  that only sustained high heat can increase body
  temperature
• Sweating releases heat as the evaporation of
  water from the skin cools the skin and blood

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Functions of Body Fluids

• Protect and lubricate tissues
• Cerebrospinal fluid protects the brain and spinal
  cord
• Amniotic fluid protects the fetus
• Synovial fluid lubricates joints
• Tears cleanse and lubricate eyes
• Saliva moistens food for swallowing

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Functions of Electrolytes

• Electrolytes help regulate fluid balance
• Cell membranes are permeable to water, but not
  freely permeable to electrolytes
• Water moves by osmosis to areas where the
  concentration of solute is high
• This action provides a means to control movement
  of water into and out of the cells
• Osmotic pressure keeps electrolytes in solution
  from drawing liquid toward them across a
  semipermeable membrane

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Functions of Electrolytes

• Electrolytes enable nerves to respond to stimuli
• Nerve impulses are initiated at nerve cell
  membranes in response to a change in electrical
  charge across the membrane
• DepolarizationAction PotentialRepolarization
• Sodium and potassium ensure that nerve impulses
  are generated, transmitted, and completed

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Functions of Electrolytes

• Electrolytes signal muscles to contract
• Muscles are stimulated to contract in response to
  stimulation of nerve cells
• Influx of calcium into the muscle from the
  extracellular space stimulates contraction
• Muscles can relax after contraction once the
  electrical signal is complete and calcium is
  pumped out of the muscle cell

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Fluid Balance

• Thirst mechanism (hypothalamus) prompts us to
  drink when it is stimulated by
• Increased concentration of salt and other
  dissolved substances in the blood
• A reduction in blood volume and blood pressure,
  such as during profuse sweating, vomiting,
  diarrhea, or low fluid intake
• Dry mouth and throat from reduced saliva
• ADH signals the kidneys to retain water

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Fluid Balance

• Body gains fluids
• Water enters the body through beverages
• Some foods have very high water content
• Water from metabolic reactions contributes 10-14
  of daily water need

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Fluid Balance

• Sensible water loss
• Kidneys excrete water as urine
• Sweat during exercise or in hot environment
• Insensible water loss
• Skin (not sweating) or lungs during exhalation
• Significant loss
• Illness, injury, exercise, high altitude,
  pregnancy, breastfeeding, diuretics

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Water

• Water
• Essential for life
• Amount needed varies with gender, age, body size,
  health status, physical activity level,
  environment
• Sources of drinking water carbonated, mineral,
  distilled, purified, tap, bottled

ABC Video Bottled Water
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Water

• What happens if we drink too much water?
• Becoming overhydrated is rare
• Dilution of blood sodium concentration
• What happens if we dont drink enough water?
• Dehydration
• Leading cause of death around the world

Water Balance
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Sodium

• Sodium
• Major positively charged electrolyte in the
  extracellular fluid
• Blood pressure and acid-base balance
• Nerve impulse transmission
• Muscle contraction and relaxation
• Assists in glucose absorption from the small
  intestine

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Sodium

• Sodium
• AI 1,500 mg, most recommend lt 2,300 mg/day
• Processed foods are high in sodium
• High blood pressure more common from high-sodium
  diets
• Excessive intake may increase urinary calcium
  excretion in some people, which in turn may
  increase the risk for bone loss

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Sodium

• What if you consume too much sodium?
• Hypernatremia is an abnormally high blood sodium
  concentration
• Patients with congestive heart failure or kidney
  disease cannot effectively excrete sodium
• Causes high blood volume, edema (swelling), and
  high blood pressure

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Sodium

• What if you dont consume enough sodium?
• Hyponatremia is an abnormally low blood sodium
  level
• From prolonged sweating, vomiting, diarrhea
• Symptoms headaches, dizziness, fatigue, nausea,
  vomiting, and muscle cramps
• If untreated seizures, coma, and death

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Potassium

• Potassium
• Major positively charged electrolyte in the
  intracellular fluid
• Together with sodium, maintains fluid balance and
  regulates the contraction of muscles and
  transmission of nerve impulses
• High potassium intake helps maintain a lower
  blood pressure

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Potassium

• Recommended intake
• 4,700 mg/day
• Sources of potassium
• Good sources fresh fruits, vegetables, legumes,
  and whole grains
• Processing foods increases sodium and decreases
  potassium content

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Potassium

• What happens if you consume too much potassium?
• Hyperkalemia high blood potassium levels
• Can alter normal heart rhythm, resulting in heart
  attack and death
• People with kidney disease are unable to regulate
  their blood potassium levels and should avoid
  consuming potassium-containing salt substitutes

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Potassium

• What happens if you dont consume enough
  potassium?
• Hypokalemia low blood potassium levels
• Seen in people with kidney disease or diabetic
  ketoacidosis
• Can occur when taking certain diuretics and with
  extreme dehydration, vomiting, diarrhea, alcohol
  abuse, long-term consumption of natural licorice
  (glycyrrhizic acid or GZA), or eating disorder
  (abnormal heart rhythms)

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Chloride

• Functions of chloride
• In extracellular fluid
• Aids digestion hydrochloric acid (HCl) in the
  stomach
• Assists the immune system and in the transmission
  of nerve impulses
• Recommended intake
• AI 2,300 mg/day

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Chloride

• What happens if you consume too much chloride?
• Primary dietary source table salt
• Hypertension in salt-sensitive individuals
• What happens if you dont consume enough
  chloride?
• This is rare but can occur in people with severe
  dehydration, frequent vomiting, and eating
  disorders

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Phosphorus

• Functions of phosphorus
• Major intracellular negatively charged
  electrolyte
• Required for fluid balance
• Critical role in bone formation
• Regulates biochemical reactions by activating or
  deactivating enzymes (phosphorylation)
• Found in ATP, DNA, RNA, cell membranes
  (phospholipids), and lipoproteins

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Phosphorus

• Recommended intake
• RDA for phosphorus is 700 mg/day
• Sources of phosphorus
• Widespread in many foods
• High in protein foods (meat, milk, eggs)
• More readily absorbed from animal sources
• Phytic acid plant storage form
• Soft drinks

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Phosphorus

• What happens if you consume too much phosphorus?
• High blood phosphorus can occur among people with
  kidney disease or when taking too many vitamin D
  supplements
• Causes muscle spasms, convulsions
• What if you dont consume enough phosphorus?
• Deficiencies of phosphorus are rare

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Medical Disorders

• Disorders related to fluid and electrolyte
  imbalance include
• Dehydration
• Heatstroke
• Water intoxication
• Hypertension
• Neuromuscular disorders
• Obesity

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Dehydration

• Dehydration occurs when fluid loss exceeds fluid
  intake
• Commonly due to heavy exercise or high
  environmental temperatures
• Elderly and infants are at increased risk

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Heatstroke

• Heatstroke occurs from failure in the bodys
  heat-regulating mechanisms
• Hot, humid environments
• Symptoms rapid pulse, hot and dry skin, high
  body temperature, loss of consciousness
• Fatal during exercise in extreme heat
• Stop exercising when feeling dizzy, light-headed,
  disoriented, or nauseated

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Water Intoxication

• Overhydration can occur but it is rare
• Kidneys retain too much water, causing
  overhydration and hyponatremia
• Documented cases of deaths among college students
  (hazing rituals)

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Hypertension

• Hypertension major chronic disease characterized
  by high blood pressure
• Often without symptoms
• Increases a persons risk of heart disease,
  stroke, kidney disease
• Can reduce brain function, impair physical
  mobility, and cause death
• Systolic pressure over 140 mm Hg
• Diastolic pressure over 90 mm Hg

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Hypertension

• What causes hypertension?
• Primary (or essential) hypertension unknown
  cause for 90-95 of cases
• 5-10 are caused by kidney disease, sleep apnea,
  and chronic alcohol abuse
• Salt sensitivity gt50 adults with hypertension

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Hypertension

• Recommendations for reducing hypertension
• Losing weight
• Increasing physical activity
• Reducing alcohol intake
• Reducing sodium intake
• Eating more whole grains, fruits, vegetables, and
  low-fat dairy foods
• DASH diet

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Hypertension

• Medications
• Help in normalizing blood pressure
• Should also continue to practice healthful
  lifestyle changes
• Hypertension the silent killer
• Often no obvious symptoms of this disease
• Importance of regular blood pressure check

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Neuromuscular Disorders

• Electrolyte imbalances can alter nervous system
  and muscle function
• Seizures uncontrollable muscle spasms
• Muscle cramps involuntary, spasmodic, and
  painful muscle contractions

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Obesity

• Popularity of sweetened beverages (U.S.)
• 21 of calories from beverages sweetened soft
  drinks, fruit juices, sweetened bottled waters,
  bottled teas, specialty coffee
• Appetite not curbed extra calories from drinks
  are not compensated for by eating less
• Displace more nutritious beverages such as milk
  (source of protein, calcium, vitamin D, and other
  nutrients important for bone health)

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