Water and the Minerals Flashcards
Water percentage of adults body weight
60% of adults weight
Water’s functions in body fluids
- carries nutrients and waste products
- maintains the structure of large molecules
- participates in metabolic reactions
- serves as the solvent for:
Minerals, vitamins, amino acids, glucose, and many other small molecules
Water’s function
- maintains blood volume
- aids in normal body temperature regulation
- acts as a lubricant and cushion
water in the human body:
1. Intracellular (inside cells)
2. Extracellular (outside cells)
- 2/3 of total body water
- blood (intravascular)
- lymph
- digestive juices
- between cells (intercellular or interstitial)
Water balance: intake regulation - hypothalamus
initiates drinking
Water imbalances: dehydration
water output > water input
water intoxication
excessive body water contents
- rare condition in which the body water contents become too high
- occasionally seen in drug induced states
S&S: confusion, convulsion, coma, death
Hyponatremia
decreased blood sodium concentration
To maintain water balance
intake must equal output
- thirst lags behind lack of water
- risks for older adults, with decreased thirst sensation
Water excretion regulation
- regulated by brain and kidneys
- Antidiuretic hormone - a hormone released by the pituitary gland in response to high salt concentrations in the blood. the kidneys respond by reabsorbing water. ADH elevates blood pressure and is also called vasopressin
- renin and aldosterone: kidneys respond to the low blood pressure by releasing renin. renin eventually stimulates angiotensin, which stimulates the reabsorption of sodium by the kidneys as well as chloride and potassium.
Renin Angiotensin Aldosterone System
renin is produced by kidneys -> target angiotensinogen (produced by liver) -> renin breaks angiotensinogen into angiotensin I which is then turned into angiotensin II by angiotensin-converting enzyme found in kidneys and lungs -> angiotensin acts on kidneys to retain sodium to increase osmolarity of blood and shift fluid into blood and ECF to increase BP
Water sources: gain, lost, amount
Gain: liquids (550-1500), foods (700-1000), and metabolic water (200-300)
Losses (kidneys 500-1400), skin (450-900), lungs (350), GI tract (150)
The body must excrete a minimum of about 500mL each day as urine
Water recommendations and sources
- mens adequate intake: 3.7 L/day
- women’s AI: 2.7 L/day
- factors: food person eats, environmental temperature and humidity, person’s activity level
- Sources: water, other beverages (caffeinated or not), most foods (esp. fruits and vegetables)
- coffee or tea can be a fine source of water intake however pay attention to the fact that caffeine is a mild diuretic so the person will also lose more
Dehydration
loss of water from the body when outputs exceed intakes
Symptoms:
- thirst
- weakness
- exhaustion
- delirium
- death
Fluid Overload = Hypervolemia
- clinical condition in which excessive fluid in the intravascular space
- common in: CHF, end-stage Kidney failure, liver failure
S&S - edema
- cramping, headache, GI bloating
- High BP
- Shortness of breath and possible pulmonary edema
- Increased HR (can lead to abnormalities of the heart)
Nursing Implications of Fluid Volume Excess
- Frequent respiratory assessments
- Assess LOC
- Watch for edema
- Cardiovascular checks
- measure I&O and daily weights
- Fluid restriction
- Careful observation and assessment
Fluid and electrolyte balance
- electrolyte solutions = ions of salt in water
- electrolyte balance regulated closely
proteins in the cell membranes move ions into or out of the cells
kidneys regulate sodium and water - the body’s total electrolytes remain constant, while the urinary electrolytes fluctuate according to what is eaten
Sodium
+ charge; extracellular ion (outside cell)
- hypernatremia (elevated blood Na+ levels) often has more to do with dehydration then excessive sodium intakes
- hyponatremia (decreased blood Na+ levels) can have many causes but a common one is excess fluid
when trying to avoid excess fluid accumulation, keep in mind that sodium should be restricted
Potassium
+ charge; intracellular ion - inside cell
Chloride
- charge; extracellular ion - outside cell
Acid-Base balance
- electrolyte mixtures act as buffers
Buffers: compounds that can reversibly combine with hydrogen ions to maintain a constant pH - kidneys play primary role in maintaining acid-base balance (H+ and bicarbonate)
- lungs, skin and gastrointestinal systems (lungs mainly)
