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FNH 250 > Water & the Electrolytes > Flashcards

Water & the Electrolytes Flashcards

1
Q

Briefly discuss water.

A
  • essential to life
  • needed in greater quantity than any other nutrient
  • ~50-70% of body weight is water (lean tissue contains more % water than adipose tissue)
  • high heat capacity – beneficial to maintain temperature homeostasis
  • different fluid compartments in body
  • ~40 L throughout body: ICF ~25 L; ECF ~15 L
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2
Q

What happens to a cell if you drink too much or too little water?

A
  • Cells rupture and die if too much water enters (cytolysis)
  • Cells collapse and die if they lose too much water (plasmolysis)
  • “Where ions go, water follows” – helps to regulate balance of fluid in the compartments
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3
Q

Briefly discuss minerals.

A
  • ~4% of body weight
  • some act as CO-FACTORS – similar function to co-enzymes (B-vitamins) – facilitate enzymatic reactions
  • mineral salt dissolved in water separates into 2 ions (e.g., sodium chloride)
  • an ion is a charged particle
  • Cation: positively charged ion (e.g., calcium Ca2+, sodium Na+)
  • Anion: negatively charged ion (e.g., chloride Cl-, fluoride F-)
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4
Q

Describe common characteristics of minerals.

A
  • These are the only inorganic micro/macronutrients in our diet (water also inorganic)
  • retain chemical identity
  • not destroyed by exposure to heat, air, acid, agitation
  • do not directly provide energy
  • some minerals absorbed and transported freely, other minerals need special carriers to be absorbed and transported
  • minerals taken in excess can be toxic (e.g., Fluoride, Iron)
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5
Q

What affects the bioavailability (ease at which a nutrient is absorbed) of minerals?

A
  • binders in food – phytic acid in whole grains and legumes,
  • oxalic acid in vegetables can inhibit absorption of minerals
  • fibre present in foods can reduce absorption of minerals
  • digestive tract conditions (e.g., VDR for calcium absorption)
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6
Q

Where are minerals found?

A
  • water systems – rivers, oceans, streams, aquifers
  • earth’s crust – top soil, beneath the surface
  • plant systems – roots, leaves, flowers, stems
  • animal tissues – animals eat plant foods
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7
Q

Briefly describe mineral/mineral interactions.

A
  • mineral/mineral interactions exist and can inhibit the absorption of one mineral
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8
Q

Briefly describe mineral/vitamin interactions.

A
  • vitamin/mineral interactions exist that often enhance the absorption of the mineral
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9
Q

Define: electrolyte.

A

Electrolytes are ions in water conduct electricity.

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10
Q

What are the primary electrolytes required for maintaining fluid balance in body compartments?

A
  • Sodium, Na+ (primarily outside cells)
  • Chloride, Cl- (primarily outside cells)
  • Potassium, K+ (primarily inside cells)
  • Phosphorus (as phosphate), PO43- (primarily inside, also outside cells)
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11
Q

Briefly describe the flow of water and minerals across cell membranes.

A
  • water flows easily across cell membranes – no direct control
  • water follows ions > flows towards the most concentrated solution. (From hypotonic to hypertonic)
  • most cations are under controlled flow (i.e., active transport - requires ATP) across cell membranes by the action of cellular pumps (proteins)
  • anions follow cations
  • water follows ions – flows toward the most concentrated solution
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12
Q

Distinguish between hypotonic, hypertonic, and isotonic.

A

In comparing two solutions of unequal solute concentration (eg., inside and outside of a cell), the solution with the higher solute concentration is hypertonic, and the solution with the lower solute concentration is hypotonic.

Solutions of equal solute concentration are isotonic.

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13
Q

Define: Osmosis

A

The movement of water across a semipermeable membrane down its concentration gradient.

The water flows across a membrane to the most concentrated solution.

The water will move from the hypotonic solution toward the hypertonic solution until the solute concentration is the same in either solution, at which point they may be considered isotonic.

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14
Q

What does the water volume inside cells depend on?

A

Water volume inside cells depends primarily on concentrations of intracellular Potassium (K+) and Phosphate (PO43-)

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15
Q

What does the water volume outside cells depend on?

A

Water volume outside cells depends primarily on concentrations of extracellular Sodium (Na+) and Chloride (Cl-)

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16
Q

How is the amount of water in each fluid compartment controlled?

A

The amount of water in each fluid compartment is controlled by the ion concentration in each compartment (usually held within narrow ranges) and the selective movement of electrolytes across cell membranes.

  • electrical neutrality of ions must be conserved in each compartment
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17
Q

Provide two applied examples of osmosis.

A

When sprinkled with salt, vegetables “sweat” because water moves toward the higher concentration of salt outside cells.

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18
Q

Define: concentration.

A

Solute per unit volume.

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19
Q

How do electrolytes stimulate nerve action?

A
  • Through the action of Sodium-Potassium ATPase pump in nerve cell membranes
  • Sodium flows from ECF into the axon of neuron causing depolarization that triggers an action potential
  • Potassium flows out of ICF to repolarize cell membrane
  • Resting potential is re-established
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20
Q

How do electrolytes stimulate muscle contractions?

A
  • When muscle cell is stimulated, changes occur to allow increased flow of Calcium from ECF into the muscle cells, causing muscle contraction
  • Muscles relax when calcium is pumped out of the cell into extra cellular fluid.
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21
Q

Different tissues contain varying amounts of water as it is vital to life. Discuss water’s role as a medium.

A

Transport medium

  • takes nutrients to cells

Reactive medium

  • involved in many reactions inside cells

Solvent medium

  • removes waste from cells
  • UREA = major waste product from body
  • healthy urine volume ~1-2 Ltr/day
  • control of urine volume determined by protein, sodium and water nutrient intakes
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22
Q

What are the effects of extreme losses of water?

A
  • Decreased blood volume & blood pressure.
  • Low blood pressure can cause lethargy, confusion, dizziness, etc.
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23
Q

How does water retention effect health?

A
  • increased blood volume increases blood pressure
  • high blood pressure is a risk factor for heart disease and stroke
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24
Q

How are blood pressure and blood volume maintained?

A
  • kidneys continually adjust blood volume and concentration of solutes in the urine
  • hormones, enzymes, and proteins involved in maintaining blood volume and pressure
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25
Q

What is the working unit of a kidney?

A

A nephron.

Each kidney contains over one million nephrons!

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26
Q

Briefly discuss kidney function.

A
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27
Q

How does the body regulate blood volume?

A
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28
Q

How does water regulate the temperature of the body?

A
  • The high heat capacity of water and high water content of the human body benefit us by allowing us to heat up or cool down slowly
  • when perspiring, evaporation must occur to cool the body
  • 1 Ltr of perspiration may represent ~1g sodium loss (average figure)
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29
Q

Discuss water’s role as a lubricant & shock absorber.

A
  • water is the primary constituent of synovial fluid found in joints (e.g., knees, elbows)
  • water in salivary and digestive juices helps lubricate food
  • water is a shock absorber (e.g., spinal cord fluid, eye sockets, amniotic fluid)
  • amniotic fluid during pregnancy to protect the developing fetus
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30
Q

Electrolytes affect volume of fluid compartments (ECF, ICF). Where does regulation of electrolyte concentration occur?

A

GI TRACT

  • ~8 Ltr of fluids containing minerals enter the GI tract each day (internal & external sources)
  • plenty of opportunity to maintain electrolyte balance

KIDNEYS

  • major organ system regulating electrolyte and fluid balance

SWEAT

  • Sodium & Chloride - primary electrolytes lost)
31
Q

What are insensible losses of water?

A
  • losses that we are not generally aware of, including:
  • lungs – breath vapour
  • skin – perspiration (water, salts, acids)
  • feces – metabolic and dietary fluids
  • ~1/2 of all water losses each day – very important to replenish!
32
Q

What is the estimated need of water per day?

A

~ 1 - 1.5mL/kcal expended

33
Q

What is the best indicator of adequate water intake?

A
  • healthy urine volume ~1-2 Ltr/day
  • best indicator of adequate water intake is a pale yellow urine colour
34
Q

What are the signs of dehydration?

A
35
Q

What is thirst?

A
  • as blood loses water, it becomes more concentrated
  • neural and brain sensors detect higher concentration
  • body weight loss in water of ~1-2% signals thirst
  • thirst lags behind body’s need for water; thirst is not a reliable signal
  • air travel: lose ~200mL/hour of travel
  • best to be proactive and keep well hydrated throughout the day
  • 1 mL water = 1 gram, 1 Ltr water = I kg
36
Q

What is constitutes ‘continued’ or ‘prolonged’ thirst?

A
  • weight loss in water of ~3-5% and body starts to conserve water
  • brain releases ADH causing the kidneys to retain water rather than excrete it in the urine
  • reduced urine production, dry mouth…
  • must replenish insensible losses
37
Q

What is dehydration?

A
  • due to lack of adequate intake of water or increased losses of water
  • darker urine colour
38
Q

Discuss water toxicity.

A

Water toxicity occurs when the kidneys’ ability to excrete excess water is exceeded!

  • can lead to HYPONATREMIA, low sodium concentration in the blood (<135mEq/L of sodium)
  • imbalanced fluid compartments
  • extreme cases can lead to death (e.g., marathon runners)
  • symptoms: headache, blurred vision, diarrhea, exhaustion, confusion
39
Q

Describe good sources of water in food.

A
40
Q

What are the daily recommendations for water?

A

Note: caffeinated beverages can count toward water needs, however these beverages will result in slight water losses from the body

  • adults: 1-1.5 mL/kcal expended
41
Q

What are major minerals for electrolyte balance?

A

Sodium

Potassium

Chloride

Phosphorus

42
Q

What role does Sodium (Na+) play as an electrolyte?

A
  • Sodium is an electrolyte regulator of fluid
43
Q

What role does Potassium (K+) play as an electrolyte in the body?

A
  • Potassium is an electrolyte regulator of fluid
44
Q

How is active transport used to calibrate cation electrolytes?

A
  • requires cellular energy + protein
45
Q

What is Sodium’s effect on blood pressure?

A
46
Q

What is potassium’s effect on blood pressure?

A
47
Q

How are Sodium & Potassium involved in nerve conduction and muscle contraction?

A
  • Na+ entering neuron causes depolarization allows movement of action potential along axon to stimulate muscle
  • Calcium moves from ECF into muscle cells causing muscle contraction
  • Neuron voltage differential re-balanced across membrane by moving K+ out of cell
48
Q

How is Sodium involved in nutrient absorption?

A
  • active transport of critical nutrients (e.g., glucose) into intestinal cells requires a sodium-dependent glucose transporter protein in the membrane
49
Q

How is Sodium involved in blood pH regulation?

A
  • kidneys can swap H+ for Na+ ions to excrete acid in the urine and maintain normal blood pH (7.35-7.45)
50
Q

Discuss alkalosis and acidosis.

(Recall Chem 123 blood pH lab)

A
51
Q

What are specific health issues related to Sodium?

A

Urine Output

  • urine volume is proportional to Na+ intake

Hypertension (high blood pressure)

  • ~10-15% of the population is sensitive to NaCl
  • almost everyone should lower their salt intake to meet DRI-AI (1500mg/day)
  • adapting to a lower intake of salt will take time – try using herbs, spices, garlic, or lemon juice
  • normal blood pressure 120/80, or lower

Calcium Loss in Urine

  • a possible concern with high sodium and low Calcium intakes
  • 1 tsp. salt results in ~40mg Calcium loss in urine
52
Q

What is hyponatremia?

A
  • Sodium deficiency
  • Low risk for most people; due to losses, not low intake (Current intakes above UL (2300 mg/day) Almost 100% bioavailability)
  • Symptoms: muscle cramps, nausea, dizziness
53
Q

What is hypokalemia?

A
  • Potassium deficiency
  • life threatening
  • Symptoms: irregular heart beat
  • Low risk, most likely due to increased losses (diarrhea, vomiting, etc.)
  • About 90% bioavailability
54
Q

What are food sources of sodium?

A
55
Q

What are food sources of potassium?

A

Avocadoes!

Bananas!

Broccoli!

Potato!

56
Q

What proportion do minerals exist in a body?

A
57
Q

Briefly introduce Chloride as it exists in the body.

A
58
Q

Briefly introduce Phosphorus as it exists in the body.

A
59
Q

What role does Chloride (Cl-) play as an electrolyte?

A
  • Chloride is an electrolyte regulator of fluid.
60
Q

What role does Phosphorus (PO43-) play as an electrolyte?

A
  • ​​Phosphorus is an electrolyte regulator of fluid
61
Q

What important roles does Chloride play, electrolyte roles aside.

A
62
Q

What important roles does Phosphorus play in the body, electrolyte roles aside.

A
  • Bone: ~85% of body P is found in major bone mineral crystal, HYDROXYAPATITE (Ca10[PO43-]6[OH]2)
63
Q

What are the recommended daily requirements for Chloride?

A
64
Q

What are the daily intake requirements for Phosphorus?

A
65
Q

Discuss deficiency & toxicity for Chloride and Phosphorus.

A
66
Q

What are food sources for Chloride?

A
67
Q

What are food sources for Phosphorus?

A

Edamame!

Sunflower seeds!

Broccoli!

68
Q

Which statement correctly describes osmosis?

  • the volume of water in each fluid compartment
  • the pressure needed to prevent movement of water across a semi-permeable membrane
  • the concentration of electrolytes in each fluid compartment
  • the permeability of membranes to ion movement
  • the movement of water across a membrane to the more concentrated solution
A
  • the movement of water across a membrane to the more concentrated solution
69
Q

Henry lost 0.5 kg in body weight during his workout at the gym today. How much water should he drink to restore his pre-workout fluid balance?

(Note: 1 cup = 250 mL = 250 g).

A

2 cups

70
Q

Which of the following meals is lowest in Vitamin C?

  • roast beef, carrots, noodles and black tea
  • hot dog, kiwi, French fries and milk
  • toast, peanut butter, grapefruit and coffee
  • spaghetti with tomato sauce, meatballs, garlic bread and red wine
  • tofu, potatoes, bell peppers, strawberries and carrot
A
  • roast beef, carrots, noodles and black tea
71
Q

Processed foods are the most common source of what two minerals?

A

Sodium & chloride

72
Q

What is the effect of the hormone aldosterone?

A
  • causes kidneys to retain sodium in the bloodstream
73
Q

[…] is the major cation electrolyte found in the intracellular fluid compartment.

A

Potassium

FNH 250 (11 decks)

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