1. Chapter 9: Nutrients Involved in Fluid and Electrolyte Balance
© 2017 Pearson Education, Inc.

2. 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
© 2017 Pearson Education, Inc.

3. 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
© 2017 Pearson Education, Inc.

4. © 2017 Pearson Education, Inc.

5. 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
© 2017 Pearson Education, Inc.

6. Electrolytes
Electrolytes are dissolved substances that disassociate in solution into electrically charged particles called ions
Positive charge (cations): sodium, potassium
Negative charge (anions): chloride, phosphorus
Predominant electrolytes
Extracellular fluid: sodium, chloride
Intracellular fluid: potassium, phosphorus
© 2017 Pearson Education, Inc.

7. 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, water-soluble vitamins, minerals, some medications
Fatty substances must be attached to or surrounded by water-soluble proteins
© 2017 Pearson Education, Inc.

8. 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
© 2017 Pearson Education, Inc.

9. Functions of Body Fluids
Fluids account for blood volume
Antidiuretic hormone (ADH) released from the pituitary gland stimulates the kidneys to reabsorb water, reducing urine output
Enzyme renin secreted from the kidneys responds to decreased blood pressure; catalyzes the conversion of blood protein angiotensinogen to angiotensinogen I
© 2017 Pearson Education, Inc.

10. Functions of Body Fluids
Fluids account for blood volume
Angiotensin I is converted to Angiotensin II (vasoconstrictor); increases blood pressure
Hormone aldosterone secreted from the adrenal glands signals the kidneys to retain sodium and chloride, thereby retaining water, increasing blood pressure, and decreasing urine output
© 2017 Pearson Education, Inc.

11. © 2017 Pearson Education, Inc.

12. Functions of Body Fluids
Fluids help maintain body temperature
Fluids maintain body temperature 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
© 2017 Pearson Education, Inc.

13. © 2017 Pearson Education, Inc.

14. 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
Pleural fluid allows lungs to expand and retract without friction
© 2017 Pearson Education, Inc.

15. 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
© 2017 Pearson Education, Inc.

16. © 2017 Pearson Education, Inc.

17. 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
Depolarization—Action Potential—Repolarization
Sodium and potassium ensure that nerve impulses are generated, transmitted, and completed
© 2017 Pearson Education, Inc.

18. © 2017 Pearson Education, Inc.

19. Functions of Electrolytes
Electrolytes signal muscles to contract
Muscles are stimulated to contract in response to stimulation of nerve cells
Increased flow of calcium ions from its storage site into the muscle stimulates muscle contraction
Muscles can relax after contraction once the electrical signal is complete and calcium is pumped out of the muscle cell
© 2017 Pearson Education, Inc.

20. Fluid Balance Fluids gained through consumption and metabolism
As much as 90% of fluids needs met by beverages and food
Metabolic water formed from metabolic reactions contributes 10–14% of the water the body needs each day
© 2017 Pearson Education, Inc.

21. Fluid Balance
Thirst mechanism (hypothalamus) prompts us to drink. 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
© 2017 Pearson Education, Inc.

22. © 2017 Pearson Education, Inc.

23. Fluid Balance Sensible fluid loss Kidneys excrete water as urine
Sweat during exercise or in hot environment
Insensible fluid loss
Skin (not sweating) or lungs during exhalation
Significant loss
Illness, traumatic injury, blood donation, surgery, exercise, high altitude, low humidity, pregnancy, breastfeeding, diuretics
© 2017 Pearson Education, Inc.

24. How Much Water Should We Drink?
Requirements are individualized
Amount needed varies with age, body size, health status, physical activity level, environment
Athletes, highly active people, and people working in hot environments may need additional fluid to replace fluid lost in sweat
Sources of drinking water: tap, carbonated, mineral, bottled
Distilled and purified water not suitable for drinking
© 2017 Pearson Education, Inc.

25. © 2017 Pearson Education, Inc.

26. Minerals Contribute to Fluid Balance
Major extracellular cation
Functions of sodium:
Allows cells to maintain fluid balance
Blood pressure regulation
Transmission of nerve signals
Muscle contraction and relaxation
Assists in glucose absorption from the small intestine
© 2017 Pearson Education, Inc.

27. Sodium
How much sodium?
AI: 1.5 g/d; other health groups recommend no more than 2.3 or 2.4 mg/d
Found naturally in many foods, processed and restaurant foods are high in sodium
High sodium diets associated with high blood pressure
© 2017 Pearson Education, Inc.

28. © 2017 Pearson Education, Inc.

29. Sodium (cont.) What if you consume too much sodium?
Hypernatremia is 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
© 2017 Pearson Education, Inc.

30. Sodium (cont.) What if you don't consume enough sodium?
Hyponatremia is 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
© 2017 Pearson Education, Inc.

31. Potassium Major intracellular cation
Together with sodium, maintains fluid balance, regulates transmission of nerve impulses, and muscle contraction
High potassium intake helps maintain a lower blood pressure
How much potassium?
Recommended intake is 4.7 g/day
© 2017 Pearson Education, Inc.

32. Potassium (cont.) Sources of potassium
Good sources include: fresh fruits, vegetables, legumes, and whole grains
Processing foods increases sodium and decreases potassium content
© 2017 Pearson Education, Inc.

33. © 2017 Pearson Education, Inc.

34. Potassium (cont.) 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
© 2017 Pearson Education, Inc.

35. Potassium (cont.) What happens if you don't 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)
© 2017 Pearson Education, Inc.

36. Chloride Major extracellular anion Functions of chloride
Assists with fluid balance
Aids digestion: hydrochloric acid (HCl) in the stomach
Assists the immune system
Transmission of nerve impulses
Recommended intake
AI: 2.3 g/day
© 2017 Pearson Education, Inc.

37. Chloride (cont.) What happens if you consume too much chloride?
Primary dietary source: table salt
Hypertension in salt-sensitive individuals
What happens if you don't consume enough chloride?
This is rare but can occur in people with severe dehydration, frequent vomiting, and eating disorders
© 2017 Pearson Education, Inc.

38. Phosphorus (cont.) Major intracellular anion Functions of phosphorus:
Fluid balance maintenance
Critical role in bone formation
Regulates biochemical reactions by activating or deactivating enzymes (phosphorylation)
Found in ATP, DNA, RNA, cell membranes (phospholipids), and lipoproteins
© 2017 Pearson Education, Inc.

39. Phosphorus (cont.) 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 (beans, whole grains, nuts)
Soft drinks
© 2017 Pearson Education, Inc.

40. © 2017 Pearson Education, Inc.

41. Phosphorus (cont.) 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 don't consume enough phosphorus?
Deficiencies of phosphorus are rare
© 2017 Pearson Education, Inc.

42. Disorders Related To Fluid And Electrolyte Imbalance
Dehydration
Heat stroke
Water intoxication
Hypertension
Neuromuscular disorders
Kidney disorders
Congestive heart failure
Obesity
© 2017 Pearson Education, Inc.

43. © 2017 Pearson Education, Inc.

44. 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
© 2017 Pearson Education, Inc.

45. © 2017 Pearson Education, Inc.

46. Heat Stroke
Heat stroke occurs from failure in the body's 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
© 2017 Pearson Education, Inc.

47. Water Intoxication
Overhydration (water intoxication) can occur, but it is rare
Kidneys retain too much water, causing overhydration and hyponatremia
Documented cases of deaths among college students (hazing rituals)
© 2017 Pearson Education, Inc.

48. Hypertension
Hypertension: major chronic disease characterized by high blood pressure
Often without symptoms
Increases a person's 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
© 2017 Pearson Education, Inc.

49. Hypertension (cont.) What causes hypertension?
Primary (or essential) hypertension: unknown cause for 90–95% of cases
5–10% of cases are caused by kidney disease, sleep apnea, and chronic alcohol abuse
Salt sensitivity: about 2/3 adults with hypertension
© 2017 Pearson Education, Inc.

50. Hypertension (cont.) Recommendations for reducing hypertension:
Losing weight
Regular exercise
Limiting alcohol intake
Reducing sodium intake
Eating more whole grains, fruits, vegetables, and low-fat dairy foods
DASH diet
Avoid tobacco products
© 2017 Pearson Education, Inc.

51. © 2017 Pearson Education, Inc.

52. Hypertension (cont.) 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
© 2017 Pearson Education, Inc.

53. Neuromuscular Disorders
Electrolyte imbalances can alter nervous system and muscle function
Seizures: uncontrollable muscle spasms
Muscle cramps: involuntary, spasmodic, and painful muscle contractions
© 2017 Pearson Education, Inc.

54. Kidney and Heart-Related Disorders
Kidney disorders
Kidneys have major role in regulation of fluid, electrolyte, and acid-base balance
Kidney disease can lead to edema and fluid retention
Congestive heart failure
Heart can no longer pump adequate supply of blood throughout the body
Heart can fail on the left or right sides, with varying consequences
© 2017 Pearson Education, Inc.

55. Obesity Popularity of sweetened beverages (U.S.)
20% of calories from beverages: sweetened soft drinks, fruit juices, sweetened bottled waters, energy drinkds, 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)
© 2017 Pearson Education, Inc.