Sodium and Water Balance Flashcards
differentiate the intracellular from the extracellular components by:
a. distribution & composition of water
b. electrolyte concentrations
A: ICF compartment is the larger of the two compartments. ECF is the smaller of the two compartments.
B: ECF has large amounts of sodium and chloride and moderate amounts of bicarb, but only small amounts of potassium, magnesium, calcium and phosphorous.
relate the concept of the concentration gradient to diffusion and osmosis.
diffusion is the movement of charged or uncharged particles along a concentration gradient. Diffusion is natural. Particles undergoing diffusion move from a higher concentration to an area of lower concentration.
osmosis is the movement of water across a semipermeable membrane. As with particles, water diffuses DOWN the concentration gradient, moving from the side of the membrane with the lesser number of particles and greater concentration of water to the side with the greater number of particles and lesser concentration of water.
define tonicity and explain how it affects cell volume/size
tonicity: refers to the tension or effect that the effective osmotic pressure of a solution with impermeable solutes exerts on cell size because of water movement across the cell membrane.
Tonicity is the relative concentration between intracellular and extracellular effects movement of water into and out of cells
AND, therefore cell size
define the terms hydrostatic pressure and osmotic pressure, as they relate to the capillary fluid and the interstitial fluid.
hydrostatic pressure: the pushing force exerted by a fluid.
osmotic pressure: the pulled forced created by the presence of evenly dispersed particles, such as the plasma proteins that cannot pass through the pores of the capillary membrane.
see also: force required to push a solvent through solution.
hydrostatic pressure is more prevalent with the interstitial fluid, and osmotic pressure is more prevalent with the capillary fluid.
describe the roles of the hormones ADH and aldosterone on sodium and water balance.
WATER:
ADH increases water reabsorption by increasing the nephron’s permeability to water, while aldosterone works by increasing the reabsorption of both sodium and water.
SODIUM:
ASK ABBY
concerning extracellular fluid volume, contrast volume deficit and volume excess by the causes and clinical signs.
volume deficit
volume deficit: causes:
Vomiting/diarrhea Gastric suctioning Diuretics Sweating, exercise Adrenal insufficiency Hemorrhage Diaphoresis (excessive sweating) Third-spacing (accumulation of fluid from the blood within body cavities, intestinal areas, or areas of the body that normally contain little fluid)
volume deficit: clinical signs Weight loss (1 L = 1 kg) Not always HR BP (Orthostasis) Delayed cap refill Neuro signs (brain is working harder than normal) Oliguria (low urine output) Skin, membranes (skin is rough, dry and flaky, slow turgor)
concerning extracellular fluid volume, contrast volume deficit and volume excess by the causes and clinical signs.
volume excess
volume excess: causes: Excessive aldosterone Excessive isotonic fluid administration Kidney disease (acute and chronic) Cushing disease and corticosteroids Heart failure, liver failure What about salt intake?
volume excess: clinical signs: Weight gain Edema Pulse (tachy, bounding) Neck veins Lungs Orthopnea
normal sodium levels in the body
A normal blood sodium level is between 135 and 145 milliequivalents per liter (mEq/L). Hyponatremia occurs when the sodium in your blood falls below 135 mEq/L.
normal potassium levels in the body
HOW MANY BANANAS?
3.5-5 mEq/dL
**you usually only buy 3-5 bananas at the store
normal hematocrit levels in the blood
men and women
for men: 40-50%
for women: 37-47%
contrast hyponatremia with hypernatremia concerning causes and effect on cell size.
Hyponatremia
Excessively dilute extracellular fluid—>low osmolality
Gain of more water than salt
Cell would swell and burst. uh oh :0
Causes: SIADH, inflammation and stress, psychogenic polydipsia, beer potomania, IV fluids, medications (SSRIs), thiazide diuretics, replacing only water (not electrolytes)
hypernatremia
Water deficit, hyperosmolality
Basic: gain more salt than water, lose more water than salt
Causes: hypertonic feedings and IV fluids, reduced fluid intake, reduced access to fluids, difficulty ingesting, altered thirst
Diabetes insipidus, osmotic diuretics, fluid loss through V/D and sweating without replacement
contrast hyponatremia with hypernatremia concerning clinical signs
clinical signs: hyponatremia:
Malaise, anorexia, nausea, vomiting, headache
Severe: confusion, lethargy, seizures, coma (cerebral edema)
clinical signs: hypernatremia:
Thirst, decreased UOP
What happens to neurons?
Confusion, lethargy, seizures, coma
contrast dehydration with edema
Edema: palpable swelling produced by expansion of the interstitial fluid volume
causes: increase capillary filtration pressure, decrease the capillary colloid osmotic pressure, increase capillary permeability, produce obstruction to lymph flow.
Tx: maintaining life (if swelling involves vital structures, correcting/controlling the cause, and precenting tissue injury, diuretics commonly used, TED hose as well.
Dehydration: occurs when you use or lose more fluid than you take in, and your body doesn’t have enough water and other fluids to carry out its normal functions.
causes: Extreme thirst, Less frequent urination, Dark-colored urine
Fatigue, Dizziness, Confusion
Tx: fluid replacement ASAP
explain the various physiologic mechanisms that cause edema.
decreased capillary colloidal osmotic pressure: when the force necessary to pull fluid back into the capillary is lacking, so fluid builds up in the tissues (edema) as a result.
increased capillary permeability: when the capillary pores become enlarged or the integrity of the capillary wall is damaged, capillary permeability is increased. This allows for plasma proteins and other osmotically active substances to leak back out, increasing the accumulation of interstitial fluid.
obstruction of lymph flow: if fluid cannot rely on the lymphatic system for movement back into the circulatory system, edema will begin to build up.
FLUID HAS TO MOVE. EDEMA INHIBITS THE MOVEMENT OF FLUID.
differentiate edema from third space fluid accumulation.
edema is caused by increase capillary pressure, decreased colloidal osmotic pressure, increased capillary permeability, and obstruction of lymph flow.
third space fluid accumulation is where the fluid is lost or trapped in the ECF or the transcellular space. Third space fluid accumulation is causes by systemic inflammatory response syndrome, leaky capillary syndrome (pancreatitis), hypoalbuminemia (severe liver failure)
