Water & Electrolytes Flashcards

1
Q

What are the functions of water?

A
  • solvent
  • transport
  • lubrication
  • protection
  • regulation of body temperature
  • involved in chemical reactions such as hydrolysis and condensation
  • maintenance of acid-base balance
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2
Q

What is the distribution of water in the body?

A
  • blood made up of 90% water
  • muscle about 75%
  • bone 25%
  • adipocytes contain only about 10% water
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3
Q

We need to take in the same amount of water than we lose because?

A
  • need to constantly intake water because we are losing it, and we cannot make it
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4
Q

How much water to we need a day?

A
  • intake varies by individual and should let thirst guide your intake
  • no scientific evidence to support the 8 glasses a day rule
  • aim for around 1500 mL a day
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5
Q

How is water intake and loss regulated?

A
  • thirst center in hypothalamus senses decreased blood volume and increased solute concentration
  • stimulates thirst
  • pituitary gland releases ADH to increase water reabsorption in kidneys
  • this thirst center doesn’t work quite as well in elderly
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6
Q

Who is at higher risk fr dehydration?

A
  • athletes
  • infants
  • overweight
  • older adults
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7
Q

What is water intoxication?

A
  • too much water consumed
  • leads to hyponatremia, causes water to move out of blood into cells
  • can cause edema in brain and increased ICP
  • athletes can also be prone to this
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8
Q

What are food sources of water?

A
  • water obtained from solid food sources as well as from drinks
  • fruits, vegetables, and dairy products are especially high in water
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9
Q

What is the distribution of water in and between cells?

A
  • 2/3 of body water is contained in cells
  • 1/3 of body water is the ECF
  • ECF includes blood, lymph, and interstitial fluid
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10
Q

What is osmosis, and how does it influence BP?

A
  • water moves in direction of higher concentration of solutes
  • high BP can push water out of capillaries
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11
Q

Why is acid-base balance important?

A
  • narrow range of pH necessary to maintain life (7.35-7.45)
  • maintained by kidneys and lungs to get rid of acids
  • buffers include bicarbonate, phosphate, and hemoglobin
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12
Q

What are the principle electrolytes?

A
  • sodium, potassium, chloride
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13
Q

In the western diet, which electrolyte is consume in excess, and which is too little?

A
  • salt (sodium chloride) often consumed in excess, as it is in many processed foods
  • not enough potassium consumed, found in unprocessed foods
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14
Q

What are the RDIs for the electrolytes?

A
  • sodium AI: 1500 mg/day
  • sodium UL: 2300 mg/day
  • chloride AI: 2300 mg/day
  • chloride UL: 3600 mg/day
  • potassium AI: 4700 mg/day
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15
Q

Who is at higher risk for hypertension?

A
  • African Americans and Hispanics
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16
Q

Are people meeting the AI of sodium and potassium?

A
  • No; most Canadians consume over the UL of sodium at 2500-3500 mg/day
  • only about 5-10% of people consuming enough potassium, which is due to lack of fruits and vegetables in diet
17
Q

How does excess sodium cause hypertension?

A
  • water moves from cells to vessels, where there is a higher concentration of solutes
  • sodium mostly extracellular
  • increased blood volume
18
Q

What is the sodium-potassium pump?

A
  • maintains resting membrane potential for APs by keeping potassium inside and sodium outside
  • uses about 20-40% of REE to maintain
19
Q

What is the main mechanism by which BP is controlled?

A
  • RAA system – decreased BP leads to release of renin, angiotensin II constricts blood vessels, also increases aldosterone, which causes fluid retention
  • net effect is increased BP
20
Q

What is hypertension?

A
  • ideally BP<120/80
  • BP>140/90 defines hypertension
  • hypertension increases risk of CVD, MI, stroke
21
Q

How can electrolyte deficiency occur, and what are the risks?

A
  • deficiency may occur due to heavy sweating, chronic diarrhea, vomiting or kidney disorders
  • medications such as thiazide diuretics, used for hypertension or heart failure, may cause potassium loss, potassium supplements may be prescribed
  • deficiencies can lead to acid-base imbalance, confusion, apathy, muscle cramps, constipation, poor appetite and eventually irregular heartbeat
22
Q

How strong is the correlation between hypertension and salt intake?

A
  • there is a relationship, but high intakes of fibre, potassium, calcium and magnesium are protective
  • high intake of salt is often accompanied by other bad habits that raise BP
23
Q

What is the DASH diet?

A
  • dietary approaches to stop hypertension
  • NIH compared reduced salt intake and DASH intake to effect on BP
  • more fruit, vegetables, less processed foods
  • combination of the DASH diet and low sodium intake lowered BP the most
  • proves not just sodium, also lack of other nutrients