Water (Fluid & Electrolyte Balance)

Intracellular fluid

within the cells and accounts for 65% of body fluid

Extracellular fluid

water outside the cells which accounts for 35% of body fluid. Made up of intravascular and interstitial fluids (between cells)

Functions of water

Component of all body tissues providing structure and form, solvent for nutrients and body wastes and chemical reactions, provides transport for nutrients and wastes via blood and lymphatic system, essential for hydrolysis and thus metabolism, lubricant in joints and in digestion, helps regulate body temperature by evaporation of perspiration, and serves as a shock absorber

Fluid and electrolyte balance

Water lost through urination, feces, perspiration, and the respiratory tract must be replaced in volume and electrolyte content. Electrolytes are measured in milliequivalents/liter

Osmolality

Number of particles per kilogram of solution; solutions with high osmolality exert more pressure than those with fewer particles

Which direction does water flow?

Toward the area of higher solute concentration; low to high

Which electrolytes maintain the water balance?

Potassium for intracellular fluid, and sodium for extracellular fluid

Vascular osmotic pressure

high concentration of electrolytes in the blood; low blood volume or blood pressure

How does the hypothalamus control thirst?

When electrolytes in the extracellular fluid are increased, water moves out there, dehydrating the cell, so it stimulates the pituitary gland to excrete antidiuretic hormone when electrolytes become too concentrated in the blood or blood volume or pressure is too low. Causes thirst and kidneys to save water

How about when sodium in ECF is reduced?

Water flows into the cells, which swell in cellular edema. Kidneys increase amount of sodium absorbed to turn things back

Some causes of dehydration?

Diarrhea, vomiting, excessive urination or perspiration, or diuretics

Signs of dehydration?

Low blood pressure, thirst, dry skin, fever, and mental disorientation

Four stages of heat illness?

Heat fatigue

Heat cramp

Heat exhaustion

Heat stroke

Can too much water be harmful?

Yes, a positive water balance leads to edema. It is rare, but it can lead to hypothryoidism, congestive heart failure, hypoproteinemia and other conditions because also sodium may not be excreted normally

pH range of blood plasma

7.35 to 7.45

pH range of intracellular fluid

6.8

How does a person's diet affect acidity?

It does not affect the body, but the urine

pH of urine

They can excrete urine from pH 4.5 to 8, average 6

Buffer system

Mixture of a weak acid and strong base to maintain pH. Ratio of base to acid is 20:1. The body's buffer system is carbonic acid and sodium bicarbonate

Acidosis

Can be caused by renal failure, uncontrolled diabetes mellitus, starvation, or severe diarrhea. Body is unable to balance the need for bases with the amount of acids it is retaining

Alkalosis

Can occur when the body has suffered a loss of hydrochloric acid from sever vomiting or has ingested too much alkali, like too many antacid tablets