Nutrition Exam 4: Module 7 - Water and Electrolytes

What percent of a person's body weight is water?

50-70%

Where does the water in our bodies come from?

food, drink, and a byproduct of metabolism

Minimum amount of water for a human a day?

2.5L/day or 2500 mL

Intake: metabolism

250 mL (10%)

Intake: food

750 mL (30%)

Intake: liquids

1500 mL (60%)

Output: sweat

200 mL (8%)

Output: feces

100 mL (4%)

Output: skin and lungs

700 mL(28%)

Output: urine

1500 mL(60%)

The fluids in the body are what?

solutions

The liquid that dissolves the solute?

solvent

The substances dissolved in a solvent?

solute

Electrolytes

minerals that naturally carry a positive or negative electric charge

What is the function of electrolytes?

regulate fluid distribution, blood pH, muscle contractions, and nerve signaling

How are electrolytes obtained?

food and drink

What is the role of the kidneys with electrolytes?

filtering out excess electrolytes for excretion in the urine

What are the main electrolytes?

sodium, chloride, potassium, magnesium, and calcium

Fluid composition: intracellular

2/3

Fluid composition: extracellular

1/3

What are bodily fluids composed of?

water, electrolytes, and other dissolved substances such as sugar, fats and proteins

How are electrical and chemical gradients created between intracellular and extracellular fluid?

different concentrations of electrolytes in the intracellular and extracellular fluid

What determines where water will move via osmosis and is involved in creating action potentials in nerves and muscles?

the electrolyte gradients

Tonicity

a measure of solute concentration across a membrane

Hypotonic

less solute concentration in extracellular fluid than intracellular fluid - cell will expand

Isotonic

same solute concentration in extracellular fluid and intracellular fluid

Hypertonic

higher solute concentration in extracellular fluid that intracellular fluid - cell will shrink

At the arterial end of a capillary, what is the pressure and movement?

hydrostatic pressure forces fluid in capillary to be filtered into the interstitial fluid

At the venous end of a capillary, what is the pressure and movement?

capillary solute concentration is higher than the surrounding fluid, which pulls water into the vessel

What is the main electrolyte involved in maintaining fluid volume and blood pressure

sodium (Na+)

What is the culprit for many electrolyte imbalances?

kidney disease

What are the main imbalances associated with poor kidney function?

hyperkalemia and hyponatremia

What does prolonged or excessive vomiting lead to?

excess loss of water and electrolytes

Can excessive vomiting cause hypo or hypernatremia?

both

Dehydration

fluid loss excedes fluid intake

What can happen with dehydration?

blood can become more concentrated - and blood pressure can drop

How can someone become dehyrated?

heavy exercise or high environmental temps

Who is most at risk for dehydration?

elderly and infants

How can patients with hypertension be helped?

reducing sodium intake

How does reducing sodium intake help people with hypertension?

does not treat but can lower blood pressure

How does increasing potassium help with hypertension?

can act to relax blood vessels and aid in balancing sodium