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133 Cards in this Set
- Front
- Back
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acidosis
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an acid-base imbalance characterized by an increase in H+ concentration (decreased blood pH). A low arterial pH due to reduced bicarbonate concentration is called metabolic acidosis; a low arterial pH due to increased PCO2 is respiratory acidosis
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active transport
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physiologic pump that moves fluid from an area of lower concentration to one of higher concentration; active transport require ATP for energy
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alkalosis
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an acid-base imbalance characterized by a reduction in H+ concentration (increased blood pH). A high arterial pH with increased bicarbonate concentration is called metabolic alkalosis; a high arterial pH due to reduced PCO2 is respiratory alkalosis
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diffusion
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the process by which solutes move from an area of higher concentration to one of lower concentration; does not require expenditure of energy
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hemostasis
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a dynamic process that involves the cessation of bleeding from an injured vessel, which requires activity of blood vessels, platelets, coagulation and fibrinolytic systems
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homeostasis
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maintenance of a constant internal equilibrium in a biological system that involves positive and negative feedback mechanisms
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hydrostatic pressure
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the pressure created by the weight of fluid against the wall that contains it. In the body, hydrostatic pressure in blood vessels results from the weight of fluid itself and the force resulting from cardiac contraction.
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hypertonic solution
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a solution with an osmolality higher than that of serum
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hypotonic solution
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a solution with an osmolality lower than that of serum
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isotonic solution
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a solution with the same osmolality as serum and other body fluids. Osmolality falls within normal range for serum (280-300 mOsm/kg)
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osmolality
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the number of osmoles (the standard unit of osmotic pressure) per kilogram of solution. Expressed as mOsm/kg. Used more often in clinical practice than the term osmolarity to evaluate serum and urine. In addition to urea and glucose, sodium contributes the largest number of particles to osmolality.
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osmolarity
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the number of osmoles (the standard unit of osmotic pressure) per LITER of solution. It is expressed as milliosmoles per liter (mOsm/L); describes the concentration of solutes or dissolved particles.
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osmosis
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the process by which fluid moves across a semipermeable membrane from an area of low solute concentration to an area of high solute concentration; the process continues until the solute concentrations are equal on both sides of the membrane
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tonicity
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the measurement of the osmotic pressure of a solution; another term for osmolality
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urine specific gravity measures...
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the kidneys' ability to excrete or conserve water
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specific gravity varies inversely with...
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urine volume. normally, the larger the volume of urine, the lower the specific gravity.
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top 2 best indicators for urine concentration
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1. urine osmolality
2. urine specific gravity |
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what can cause a falsely elevated specific gravity?
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increased glucose or protein in the urine
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SERUM osmolality primarily reflects...
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the concentration of Na, although BUN and glucose also play a major role in determining serum osmolality
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URINE osmolality is determined by...
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urea, creatinine, and uric acid
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normal serum osmolality
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275-300 mOsm/kg
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normal urine osmolality
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250-900 mOsm/kg
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sodium predominates in the _____ and holds ____ in this compartment
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ECF
water |
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how do you estimate serum osmolality
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by doubling the serum sodium level
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factors that increase URINE osmolality and increase URINE specific gravity
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severe dehydration
free water loss diabetes insipidus hypernatremia hyperglycemia stroke or head injury renal tubular necrosis consumption of methanol or ethylene glycol (antifreeze) |
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factors that decrease URINE osmolality and decrease URINE specific gravity
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FVE
SIADH renal failure diuretic use adrenal insufficiency hyponatremia overhydration paraneoplastic syndrome associated with lung cancer |
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factors that increase serum osmolality
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FVD
SIADH CHF acidosis |
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factors that decrease SERUM osmolality
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FVE
DI hyponatremia aldosteronism pyelonephritis |
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BUN is made up of ..
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urea, which is an end product of the metabolism of protein (from both muscle and dietary intake) by the liver. amino acid breakdown produces large amounts of ammonia molecules, which are absorbed into the bloodstream. ammonia molecules are converted to urea and excreted in the urine
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normal BUN
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10-20 mg/dL
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BUN level varies with
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urine output
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factors that increase BUN
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decreased renal function
GI bleeding dehydration increased protein intake fever sepsis |
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factors that decrease BUN
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end-stage liver disease
low-protein diet starvation and condition that results in expanded fluid volume (e.g. pregnancy) |
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creatinine is the end product of...
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muscle metabolism
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creatinine is a better indicator of renal function than BUN because...
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it does not vary with protein intake and metabolic state
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normal serum creatinine
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0.7-1.4 mg/dL
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creatinine concentration depends on (in a normal person)
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lean body mass and varies from p2p
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as renal function decrease, serum creatinine levels
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increase
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normal hematocrit male
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42-52% male
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normal hematocrit female
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35-47% female
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factors that increase the hematocrit
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dehydration
polycythemia |
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factors that decrease hematocrit
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overhydration
anemia |
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urine sodium values change with
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sodium intake and the status of flui volume
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normal URINE sodium
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75-200 mEq/24h
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a random specimen of urine contains more than _____ of sodum
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40 mEq/L
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urine sodium levels are helpful in the diagnosis of
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hyponatremia
acute renal failure |
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How much plasma do the kidneys filter each day? How much urine is excreted?
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180 L
1.5 L |
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how do the kidneys regulate ECF volume and osmolality?
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by selective retention and excretion of body fluids
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how do the kidneys regulate electrolyte levels in the ECF?
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by selective retention of needed substances and excretion of unneeded substances
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How do the kidneys regulate the pH of the ECF?
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by retention of hydrogen ions
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how do the kidneys regulate metabolic wsates and toxic substances?
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by excreting them
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name 3 things that decline with advanced age
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renal function
muscle mass daily exogenous creatinine production |
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in the elderly, what might high-normal and minimally elevated serum creatinine values represent?
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substantially reduced renal function, in the elderly
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failure of the pumping action of the heart interferes with renal...
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perfusion and thus with water and electrolyte regulation
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in the healthy adult, through exhalation, the lungs remove approximately ...
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300 mL of water daily
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hyperpnea
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abnormally deep respiration
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what increased water loss through lungs?
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hyperpnea
continuous coughing |
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what decreases water loss through lungs?
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mechanical ventilation with excessive moisture
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normal aging results in decreased respiratory function, causing...
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increased difficulty in pH regulation in older adults with major illness or trauma
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what manufacture ADH and where is it stored?
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the hypothalamus manufactures ADH and it ADH is stored in the posterior pituitary gland and released as needed
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ADH causes ...
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the body to retain water
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functions of ADH
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maintaining the osmotic pressure of the cells by controlling the retention or excretion of water by the kidneys and by regulating blood volume
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aldosterone is a
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mineralcorticoid secreted by the zona glomerulosa of the adrenal cortex, and has a profound effect on fluid balance
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increased secretion of aldosterone causes
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sodium, and thus water, retention
potassium loss |
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decreased secretion of aldosterone causes ...
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sodium and water loss and potassium retention
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cortisol, when secreted in large quantities, can produce
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sodium and fluid retention
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secretion of PTH causes..
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and increase in serum calcium levels
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can changes in the interstitial compartment within the ECF occur without affecting body function?
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yes
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baroreceptors
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small nerve receptors that detect changes in pressure within blood vessels and transmit this information to the CNS
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low-pressure barorecptors are in the
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cardiac atria, particularly the left atrium
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high-pressure baroreceptors are in the
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aortic arch and the carotid sinus, as well as in the afferent arteriole of the juxtaglomerular apparatus of the nephron
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as arterial pressure decreases, baroreceptors
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transmit fewer impulses from the carotid sinuses and the aortic arch to the vasomotor center.a decrease in impulses stimulates the sympathetic nervous system and inhibits the PNS. the outcome is an increase in cardiac rate, conduction, and contractility and an increase in circulating blood volume. sympathtic stiumulation constricts renal arterioles; this increases the release of aldosterone, decreases glomerular fitration, and increases sodium ad water reabsorption
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about the RAA system
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decreased renal perfusion causes release of renin in the kidneys. the converts angiotensinogen into angiotensin I. ACE (angiotensin-converting enzyme) conerts angiotensin I to angiotensin II. a-II causes vasoconstriction and therefore increases arterial perfusion pressure and stimulates thirst. as the SNS is stimulated, aldosterone is released in response to an increased release of renin.
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aldosterone can be released in response to...
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release of renin
increase of serum potassium decrease of serum sodium increase of ACTH |
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wht is the most significant substance in determining whether the urine that is excreted is concentrated or dilute?
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ADH
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where are osmoreceptors?
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the surface of the hypothalamus
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what do osmoreceptors do?
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sense changes in sodium concentration. as osmotic pressure increases, the neurons become dehydrated and quickly release impulses to the posterior pituitary, which increases the release of ADH.
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osmoreceptors basically stimulate...
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the release of ADH
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where is atrial natriuretic peptide (ANP) synthesized, stored, and released?
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muscle cells of the atria of the heart
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factors that stimulate release of ANP
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increased atrial pressure
angiotensin II stimulation endothelin sympathetic stimulation any condition that results in volume expansion, hypoxia, or increased cardiac filling pressures |
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action of ANP
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decreased BP and volume
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RAA system has the opposite action of
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ANP
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normal serum ANP
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20-77 pg/ mL
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ANP increases in...
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acute heart failure
-paroxysmal atrial tachycardia -hyperthyroidism -subarachnoid hemorrhage -small cell lung cancer |
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what can improve left ventricular functionafter left ventricular aneurysm repair by decreasing myocardial fibrosis?
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ANP
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first sign of fluid deficit in young vs. elderly
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young-thirst
elderlky-confusion or cognitive impairment |
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FVD, fluid volume DEFICIT, is aka
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hypovolemia
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FVD occurs when
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loss of ECF volume exceeds the intake of fluid
-when water and electrolytes are lost in the same proportion as they exist in normal body fluids |
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dehydration is not FVD
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TRUE
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dehydration refers to
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loss of water alone, with increased sodium levels
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ration of electrolytes to water in FVD
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the same
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in FVD, might serum electrolyte concentrations be changed?
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yes, only if other imbalances are present concurrently
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causes of FVD
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abnormal fluid losses (vomiting, diarrhea, GI suctioning, sweating)
decreased intake |
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risk factors of FVD
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-DI
-adrenal insufficiency -osmotic diuresis -hemorrhage -coma -third space fluid shifts |
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characteristics of FVD (may be rapid and mild to severe)
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-acute weight loss (loss of 1lb. weight = fluid loss of 500 mL)
-decreased skin turgor (test this on sternum, forehead, or inner thighs; and serially; not as valid in elderly) -tongue turgor - more than one longitudinal furrows and tongue is smaller (not affected by age -oliguria <30mL/hr (after FVD has developed) -concentrated urine -postural hypotension -weak rapid heart rate -flattened neck veins -decreased temp -decreased CVP (if normal cardiac fning) -cool, clammy skin r/t peripheral vasoconstriction -thirst -anorexia -nausea -lassitude -muscle weakness -cramps -if renal fn is ok, specific gravity should by greater than 1.020, showing its attempt to concentrate urine and conserve water |
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lab data common in FVD
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-BUN r/t serum creatinine
-increase BUN -WNL creatinine -ratio greater than 20:1 -increase hematocrit -urine specific gravity increased (r/t kidneys attempt to conserve water, but is decreased with DI) -urine osmolality >450 -hypo-or hyper- kalemia or-natremia may occur |
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BUN can be elevated r/t
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dehydration
decreased renal perfusion and function |
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in FVD, change in potassium and sodium occur with
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-GI and renal losses->hypokalemia
-adrenal insufficiency->hyperkalemia -increased thirst and ADH release->hyponatremia -increased insensible losses and DI->hypernatremia |
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correction of fluid loss for the patient with FVD
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-oral route preferred
-to expand blood volume and increase BP -if IV-isotonic electrolyte solutions -when they become BP WNL - hypotonic electrolyte solution (to provide for electrolytes and water for renal excretion of metabolic wastes |
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ex. isotonic electrolyte solutions
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lactated Ringer's solution
0.9% sodium chloride |
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ex. hypotonic electrolyte solution
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0.45% sodium chloride
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with FVD, assess...
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I&O, weight, vital signs, CVP, LOC, breath sounds, and skin color to determine when therapy should be slowed to avoid volume overload
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with severe FVD, if the patient is oliguric, give a fluid challenge test.... to determine...
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whether the depressed renal function is caused by reduced renal blood flow 2 to FVD (prerenal azotemia) or more seriously by acute tubular necrosis
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ex. of a fluid challenge test
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give 100-200mL NS solution over 15 minutes. goal is to provide fluids rapidly enough to attian adequate tissue perfusion without compromising the CV system.
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fluid challenge results if normal renal function
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increased urine output, increase BP and increase CVP
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loss of what percent of intravascular volume can lead to shock?
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25%
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parameter of postural hypotension
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a decrease in systolic P exceeding 15 mm Hg when the patient moves from a lying to a sitting position
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what kind of IV solution is used to increase ECF volume
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isotonic solutions
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FVE aka hypervolemia refers to..
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an isotonic expansion of the ECF caused by the abnormal retention of WATER AND SODIUM in approximately the SAME PROPORTIONS in which they normally exist int he ECF
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FVE is always 2 to
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an increase in the total body sodium content, which, in turn, leads to an increase in total body water
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FVE may be r/t
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simple fluid overload
heart failure renal failure cirrhosis of the liver consumption of excessive amounts of salts -excessive admin of sodium-containing fluid in a patient with impaired regulatory mechanisms may predispose a person to FVE |
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manifestation of FVE
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-edema
-distended neck veins -crackles in lungs -increased HR -increased BP, pulse pressure, CVP -increase weight -increase urine output -SOB/wheezing |
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lab values common in FVE
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-may be decreased r/t dilution
-if chronic renal failure is the issue, both SERUM osmolality and the sodium level are decreased due to excessive retention of water, but URINE sodium level is increased if the kidneys are attempting to excrete excess volume -chest x-rays - congestion -if cirrhosis, heart failure, or nephrotic syndrome -> aldosterone is the problem, it is being chronically stimulated, so the URINE sodium level does not increase |
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medical management of FVE
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#1. dc sodium infusions
#2 sodium restrictions #3. thiazide diuretics, if severe loop diuretics #4. dialysis |
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what do diuretics do?
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reduce edema by inhibiting the reabsorption of sodium and water by the kidneys
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what does a thiazide diuretic do?
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blocks sodium reabsorption in the distal tubule, where only 5% to 10% of filtered sodium is reabsorbed
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ex. thiazides
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hydrochlorothiazide (Hydrodiuril)
metolazone (Mykrox, Zaroxolyn) |
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action of loop diuretic
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blocks sodium reabsorption in the ascending limp of the loop of Henle, where 20% to 30% of filtered sodium is normally reabsorbed
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ex. loop diuretics
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- furosemide (Lasix)
- bumetanide (Bumex) - torsemide (Demadex) |
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what electrolyte imbalances can occur with diuretics?
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- all diuretics except those that work in the last distal tubule (spironolactone) -->hypokalemia (and hyperkalemia can occur with the spironolactone!)
-the increased release of ADH secondary to reduction in circulating volume can --> hyponatremia (rebound effect??) -loop and thiazides--> decreased reabsorption and increased excretion of magnesium-->hypomagnesium |
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azotemia def
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increased nitrogen levels in the blood
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azotemia can occur with FVE when
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urea and creatinine are not excreted due to decreased perfusion by the kidneys and decreased excretion of wastes
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hyperuricemia can occur in FVE with
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increased reabsorption and decreased excretion of uric acid by the kidneys
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nutritional therapy of FVE
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-sodium restriction (as little as 250mg, down from normal intake of 6 to 15 g salt)
-distilled water -avoid water softeners that add sodium to water in exchange for other ions -protein intake may be increased in those with low protein levels to increase capillary oncotic pressure and pull fluid out of the tissues into vessles for excretion by the kidneys |
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does sodium OR sodium salt contribute to edema?
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sodium salt (sodium chloride)
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potassium sparing diuretics
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spironolactone
triamterene amiloride |
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potassium retention is associated with what disease
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renal disease - dont give potassium containing salt substitutes
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in patients with liver damage and FVE, dont give ________
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salt substitutes containing ammonium chloride
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bed rest periods may be beneficial to the patient with FVE because
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bed rest favors diuresis of edema fluid
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with FVE, if dyspnea or orthopnea is present place the patient in what position
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semi-Fowler's to promote lung expansion
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anasarca
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severe generalized edema
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meds that can cause edema
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-NSAIDS
-estrogens -corticosteroids -antihypertensive agents |
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adrenal insufficiency leads to a ...
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deficiency in aldosterone and therefore predisposes the pt to sodium deficiency
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