Fluid balance Flashcards
Contains the fluid inside the billions of cells within the body. Largest of the two compartments. 2/3 of total body water.
Intracellular fluid
Contains any fluid outside the cell. 1/3 of total body water. Divided into what three compartments?
Extracellular fluid
Interstitial and intravascular are the major
transcellular is the minor
Produced in the brain and stored in and released by the posterior pituitary gland. Results in a decreased production of urine.
Antidiuretic hormone (ADH)
Produced by the adrenal cortex through the renin-angiotensin-aldosterone system (RAAS). Regulates sodium and potassium balance but how?
Aldosterone
Circulates to the kidneys where it causes resorption of sodium and water in the distal renal tubules into the blood, causing increases in the volume of ECF.
Increases urinary excretion of potassium and hydrogen ions.
Produced from specialized cells in the atrial muscle of the heart. Released in response to stretching of the atrial muscle during periods of circulatory overload
Atrial natriuretic peptide (ANP)
Inhibits ADH by increasing loss of sodium and water in the urine. Opposes the effect of aldosterone.
What is the primary regulator of fluid intake?
Thirst. Hypothalamus is activated.
Chemical compounds that do not dissociate in solution. Are the chemical end products of carbs, proteins, fats
Non-electrolytes
Chemical compounds that dissociate in solution to form ions (charged particles)
Electrolytes
Positive are cations, negative are anions. They combine to make mineral salts/electrolytes.
What is sensible and insensible fluid loss?
Sensbile is kidneys and GI tract
Insensible (not visible) is skin and respirations
Expands fluid volume without causing a fluid shift. Expands the ECF. Have the same osmolality or tonicity as blood. Used for patients who are hypotensive due to hypovolemia.
Isotonic solutions
0.9% sodium chloride
Lactated Ringers
Allows fluids to shift out of blood vessels to move into cells. Has a lower osmolality and is more dilute than blood. Used for patients who need cellular hydration (DKA or increased glucose levels)
Hypotonic solutions
0.45% sodium chloride (half normal saline)
5% dextrose
Causes fluid to shift from the interstitial and intracellular space into the intravascular space. Has a higher osmolality and is more concentrated than blood. Used to decrease peripheral edema, stabilize BP, and adequate urinary output.
Hypertonic
D10W, D20W
3% NaCl
What is the most common electrolyte to be added to IVs?
Potassium (K+). Can only be given IV or PO. Must be diluted. Cannot be given faster than 10 mEq/hr. Max that can be given is 40 mEq/hr.
How much weight lost is equal to how much fluid?
1 kf og weight gained or lost Is equal to 1 liter of fluid gained or lost
Dehydration
Fluid overload
Hypovolemia
Hypervolemia
Decreased intake due to fluids being unavailable
Fluid deficit. Diuretic therapy, diarrhea, vomiting, gastric suctioning, anorexia, third spacing-fluid is not available or use, sweating
What are the characteristics of body fluids?
Fluid amount/volume
Concentration/osmolality
Composition/electrolyte concentration
Degree of acidity/pH
Fluid that’s between the cells and outside blood vessels
Interstitial fluid
Fluids such as cerebrospinal, pleural, peritoneal, and synovial fluids that are secreted by epithelial cells
Transcellular fluids
Examples of cations in body fluids?
Sodium, potassium, calcium, magnesium
Examples of anions in body fluids?
Chloride and bicarbonate
A measure of the number of particles per kg of water
Osmolality
Concentrations of what are higher in the ECF?
Sodium, chloride, bicarbonate
Concentrations of what are higher in the ICF?
Potassium, magnesium, and phosphate
How do cells maintain their high intracellular electrolyte concentration?
Active transport. Requires energy in the form of ATP to move electrolytes across cell membranes against the concentration gradient, from areas of lower concentration to higher.
The force of fluid pressing outward against a surface. Capillary vs interstitial fluid?
Hydrostatic pressure.
Capillary one moves fluid from capillaries to the interstitial fluid. IF is a weaker opposing force that tends to push fluid back into capillaries.
An inward-pulling force caused by blood proteins that helps move fluid from the interstitial area back into capillaries
Colloid osmotic pressure, or oncotic pressure
Normally a very small opposing force
What happens at the arterial end of a normal capillary?
Capillary hydrostatic pressure is strongest, and fluid moves from the capillary into the interstitial area, bringing nutrients into cells.
What happens at the venous end of a normal capillary?
Capillary hydrostatic pressure is weaker and the colloid osmotic pressure of the blood is stronger. Fluid moves into the capillary, removing waste products from cellular metabolism.
How does fluid distribution occur?
Between extra cellular and intracellular occurs by osmosis.
Between vascular and interstitial parts of the ECF by filtration.
An infants proportion of total body water is greater than that of children or adults. How much? Risks?
70-80%. Have greater water needs and immature kidneys. Greater risk for ECV deficit and hypernatremia because body water loss is proportionately greater per kg of body weight.
