Water: Introduction to Water Balance and Fluid Electrolyte Balance (PDF)

Water Dr Hadeel Alsufiani Chapter outline Introduction water balance and recommended intake fluid and electrolyte balance  Introduction Water is an essential nutrient, more important to life than any of the others. Water constitutes about 60% of an adult’s b...

Water Dr Hadeel Alsufiani Chapter outline Introduction water balance and recommended intake fluid and electrolyte balance  Introduction Water is an essential nutrient, more important to life than any of the others. Water constitutes about 60% of an adult’s body weight and a higher percentage of a child’s. The body maintains an appropriate balance and distribution of fluids with the help of another class of nutrients- the minerals.  In the body, water is the fluid in which all life processes occur. The water in the body fluids: Carries nutrients and Participate in Maintains blood waste products metabolic reactions volume throughout the body Act as a lubricant and Serve as the solvent cushion around joints for minerals, vitamins, and inside the eyes, amino acids, glucose Aids in the regulation the spinal cord, and, in and many other of body temperature pregnancy, the molecules so they can amniotic sac participate in surrounding the fetus metabolic reactions in the womb. Water balance and recommended intakes Fluid inside cells is called intracellular fluid, whereas fluid outside cells is called extracellular fluid. Every cell contains fluid of the exact composition that is best for that cell.  The composition of intracellular and extracellular fluids differ from each other. They continuously lose and replace their components, yet the composition in each compartment remains remarkably constant under normal conditions. Because imbalances can be devastating, the body quickly responds by adjusting both water intake and excretion as needed. Water Water excreti intake Consequently, the entire system of cells on and fluids remains in a delicate, but controlled, state of homeostasis. Water intake Thirst and satiety influence water intake in response to changes sensed by the mouth, hypothalamus, and nerves. Water sources Amount (ml) Beverages 550 to 1500 Foods 700 to 1000 Metabolism 200 to 300 Total 1450 to 2800 Water losses Water losses Amount (ml) Kidneys (urine) 500 to 1400 Skin (Sweat) 450 to 900 Lungs (breath) 350 GI tract (feces) 150 Total 1450 to 2800  Dehydration: the Water intoxication: the condition in which body rare condition in which water output exceeds the body water contents water input. are too high in all body Symptoms include thirst, fluid compartments. dry skin and mucous membranes, rapid heartbeat, low blood pressure, Water andWater weakness. Water Water intake excretion intake excretion excretion intake excretion intake intake excretion excretion intake intake excretion excretion intake Water recommendations The recommended water intake for a person who expends 2000 kcalories a day, then, is 2 to 3 liters of water ( about 8 to 12 cups). This recommendation is in line with the adequate intake (AI) for total water set by the DRI. Fluid and electrolyte balance Maintaining a balance of about two-thirds of the body fluids inside the cells and one- third outside is vital to the life of the cells. As the figure shows, some electrolytes reside primarily outside the cells. Whereas others reside predominantly inside the cells. Cell membranes are selectively permeable, meaning that they allow the passage of some molecules, but not others.  If too much water to enter the cells, they might rupture; if too much water to leave, they would collapse. To control the movement of water, the cells direct the movement of the major minerals- sodium, chloride, potassium, calcium, phosphorus, magnesium and sulfur. whenever electrolytes move across the membrane, water follows.