Water

Water

Water and Body Fluids

I H2O, Functions and roles of Water:
A. The main role of water is to maintain an appropriate water balance to support vital functions.
B. To maintain water homeostasis, intake from liquids, foods, and metabolism must equal losses from the kidneys, skin, lungs, and feces. (I & O’s = intake and output)
C. Functions;
1. Carries nutrients and waste products.
2. Maintains the structure of large molecules
3. Participates in metabolic reactions
4. Solvent for minerals, vitamins, amino acids, glucose and others
5. Lubricant and cushion around joi8nts, inside the eyes, the spinal cord, and in amniotic fluid during pregnancy
6. Regulation of body temperature (shiver and sweats)]
7. Maintains blood volume
II Water Balance
A. Intracellular fluid (inside the cells) makes up about 2/3 of the body’s water. (Adults have more intracellular fluid)
B. Extracellular fluid (outside the cells) has two components: (infants have more extracellular fluid)
1. Interstitial fluid
i. every pint of interstitial tissue = 1 lb on scale
2. Plasma
C. Water intake: thirst is a conscious desire to drink and is regulated by the mouth, brain and nerves.
III Water Deficiency
A. Dehydration: water output exceeds input due to an inadequate intake or excessive losses.
1. 1-2% loss of body weight:
a. thirst, fatigue, weakness
b. loss of appetite
2. 3-4%
a. impaired physical performance
b. dry mouth
c. reduction in urine
d. flushed skin
e. impatience
f. apathy
3. 5-6%
a. difficulty in concentrating
b. irritability
c. sleepiness
d. impaired temperature regulation
e. increased respiratory rate
4. 7-10%
a. dizziness
b. spastic muscles
c. loss of balance
d. delirium
e. exhaustion
f. collapse
IV Toxicity
A. Water Intoxication: excessive water contents in all body fluid compartments.
1. rare
V Water Sources
A. Water intake is from 3 sources:
1. liquids
a. water
b. other beverages
2. solids
a. fruits
b. vegetables
c. meat
d. cheese
3. by product of metabolism
a. CHO = CO2 & H2O (Carbs in the Krebs cycle release energy, the waste or left over byproducts are CO2 and H2O)
B. An intake of 1450 to 2800 ml of water is usually represented by:
1. liquids: 550-1500 ml
2. foods: 700-1000 ml
3. metabolic water: 200-300ml
4. Recommended intake:
a. 1 ml per kcal (2-3 liters)
b. those with increased needs are:
i. athletes
ii. infants and children
C. Water losses (output of 1450 to 2800 ml)
1. kidneys (urine output) 500 to 1400 ml
2. skin (sweat) 450 – 900 ml
3. lungs (vapor) 350 ml
4. intestines (feces) in GI tract 150 ml
5. alcohol and caffeine create a diuretic effect
VI Health Effects
A. Meeting fluid needs
1. protect against cancer of the bladder, prostrate, and breast
2. protect against kidney stones