Exam 1- Fluids And Electrolytes Flashcards
Potassium
Major determinant of the resting membrane potential necessary for transmission of nerve impulses.
Most abundant inside the cell
Sodium
Regulator of fluids
Maintenance of neuromuscular conduction of nerve impulses
134-145 meq/L
Most abundant outside the cell
Capillary Hydrostatic pressure
One of the four forces affecting filtration vs reabsorption
At the arterial end of capillaries, fluid moves from the interstitial space into the interstitial space because the capillary hydrostatic pressure is higher than the capillary oncotic pressure.
Oncotic pressure
Heavily influenced by plasma proteins. Low plasma albumin causes edema as a result of reduction in plasma oncotic pressure.
Natriuretic peptides
Released from heart when it stretches from too much fluid. Gets rid of fluid. Hormones that include atrial natriuretic peptide (ANP) produced by the myocardial atria, BNP produced by the ventricles, and urodilation within the kidney. Decrease BP and increase sodium and water excretion.
RAAS (renin angiotensin-aldosterone system)
1) When circulating blood volume or BP is reduced, renin, an enzyme secreted by the kidney, is released.
2) renin stimulates release of angiotensin 1 from the liver into the bloodstream.
3) the king releases angiotensin-converting enzyme (ACE) and converts it to angiotensin 2
4) angiotensin 2 causes vasoconstriction and stimulates release of aldosterone
5) aldosterone promotes Na reabsorption by the proximal tubules of the kidneys, thus preserving sodium, blood volume, and BP
Hypernatremia
Sodium >147
Movement of water from the cell to the extracellular fluid.
Causes: inadequate water intake, hypertonic saline, over secretion of aldosterone.
Symptoms: confusion, convulsions, cerebral hemorrhage, coma.
Hyponatremia
<135
Causes: diuretics, vomiting, diarrhea, hypotonic IV, kidney failure, heart failure, liver failure (ascites)
Symptoms:
Hyperkalemia
Causes: Addison’s disease, trauma, insulin deficiency
Symptoms: peaked T waves, arrhythmias
Hypokalemia
Causes: loop diuretics, vomiting, diarrhea
Symptoms: flattened t-waves, AV block, bradycardia, paralytic ileus.
Hypercalcemia
> 10-12 mg/dl
Causes: hyperparathyroidism, bone nets with calcium reabsorption
Symptoms: nonspecific, fatigue, weakness, lethargy, anorexia, etc.
Inverse relationship with phosphorous. Of high, the other is low.
Hypocalcemia
<8.5 mg/dl
Inadequate intestinal absorption, massive blood admin, elevated calcitonin, hypoalbuminemia
Symptoms: increased neuromuscular excitability, tingling, muscle spasms, intestinal cramping
Phosphate
Buffer in acid-base regulation Energy (ATP) for muscle contraction. Controlled by PTH. Inverse relationship with with calcium.
Low phosphate can be caused by hyperparathyroidism because calcium levels are high.
If high, we worry about the calcium level being low which can lead to arehythmias and laryngospasms.
Hydrostatic pressure
Determined by BP and blood volume.
Water movement between plasma and interstitial space
Determined by 4 forces: Capillary hydrostatic pressure (BP) Capillary (plasma) oncotic pressure Interstitial hydrostatic pressure Interstitial oncotic pressure.
Mostly relies on capillary pressure
Edema
Excessive accumulation of fluid within the interstitial space. Usually a problem with fluid distribution, not fluid excess. Four causes are increase capillary hydrostatic pressure, decreases plasma oncotic pressure, increased capillary membrane permeability, and lymphatic obstruction.
Edema from increased capillary hydrostatic pressure
Venous obstruction or sodium and water retention.
Ex: DVT, R-sides HF, tight clothing around extremities, prolonged standing, hepatic obstruction.
Edema from decreases plasma oncotic pressure
Losses or diminished production of albumin, which decreases oncotic attraction of fluid into the capillary, leaving fluid in the interstitial spaces.
Ex: liver disease, protein malnutrition, burns
Increased capillary membrane permeability
Inflammation and immune response. Fluid escapes plasma into interstitial spaces.
Ex: shock
Edema from lymphatic obstruction
Lymphatic channels blocked from tumor or infection.
SIADH
Excessive secretion of ADH, which decreases diuresis. Increases body water and dilutes urine.
Diabetes insipidus
Decreased secretion of ADH. increased diuresis, loss of body water, hypernatremia.
Aldosterone
Regulates sodium balance. Increases reabsorption of sodium by distal tubule of the kidney.
Magnesium
Major intracellular action. Regulated by PTH. Functions in enzymatic reactions and often interacts with calcium at a cellular level.
Atrial natriuretic peptide (ANP)
Stimulate by increased volume in the atria. Causes the increased renal sodium and water excretion.
Calcitonin
Stimulates by high plasma calcium. Causes inhibition of osteoclasts in bone.
Filtration
Fluid moving out of the capillary into the interstitial space
Osmosis
Fluid moving into or out of cell
Total body water
Sum of ICF and ECF. 60% of body weight.
ECF (20%) intravascular, lymph, and interstitial spaces.
ICF (40%)
Serum osmolality
Concentration of the blood.
280-300
Urine specific gravity
Concentration of the urine
1.005-1.030
High in dehydrated patients, UNLESS they have DI, because they are unable to concentrate urine.
ADH
Antidiuretic hormone, aka vasopressin
Pituitary
When released, tells kidney hold (reabsorb) sodium and water. Slows down diuresis.
Stimulated by low sodium, low blood volume or body fluid, and high osmolality of body fluids.
Magnesium
Major IC cation.
Interacts with calcium on a cellular level. Necessary for absorption and utilization of other electrolytes. Regulated by PTH.
Relaxant. Without it, our body is tense and irritable.
Chloride
Hand in hand with sodium.
Inverse relationship with bicarbonate.
Low chloride level= metabolic alkalosis
