Fluid Balance 2

  1. What is the function of renin?
    • Activates angiotensin, which is converted to angiotensin II in the lungs and causes vasoconstriction and stimulates the adrenal cortext to produce aldosterone
  2. What is the function of aldosterone?
    • Increases salt and water reabsorption in the kidney (increases blood volume)
    • Causes the kidneys to excrete potassium (K+)
    • Has an indirect effect on water because the water follows the sodium and the sodium is affects by the aldosterone
  3. Where is ADH released from and what does it do?
    ADH is released from the pituitary gland and causes water conservation, which increases peripheral vascular resistance and arterial BP
  4. What is the main determinant of extracellular fluid (ECF) volume?
    sodiom ions
  5. What would happen if there was an increase in Na+ in the plasma?
    Fluid would be pulled from the interstitial and intracellular compartments into the plasma, causing hypovolemia
  6. What is hypovolemia?
    Dehydration of the interstitial and intracellular compartments (low blood volume)
  7. What happens when there is a decrease in Na+ in the plasma?
    Fluid will move from the plasma into the interstitial and intracellular compartment (causing hypervolemia)
  8. What is the job of baroreceptors?
    Baroreceptors are connected to the vagus nerve (parasympathetic) and they detect how much blood volume there is
  9. Explain the order in which the renin-angiotensin-aldosterone system works
    • 1) Renin is release in the kidney when the kidney senses hypovolemia (low BP)
    • 2) Renin stimulates the release of Angiotensin I, which then turns into Angiotensin II
    • 3) Angiotensin II causes the retention of NA+ by the kidney (via Aldosterone), water retention by the kidney (via vasopression), increased salt appetite, increased drinking, and increased BP
  10. What is the function of Atrial Natriuetic Peptid (ANP) and what causes it to be released?
    • It is released as a result of atrial stretch
    • Lowers BV and BP by
    • -Causing vasodilation (suppressess renin-angiotensin system)
    • -Decreases aldosterone (increased urinary excretion)
    • -Increases glomerular filtration rate (increases rate of urine production/excretion)
  11. What is the function of Brain Natriuetic Peptid (BNP) and what causes it to be released?
    • Released as a result of ventricular stretch
    • Lowers BV and BP by
    • -Vasodilation
    • -Decreasing release of aldosterone
    • -Causing diuresis of sodium/water
  12. What triggers the release of antidiuretic hormone (ADH) and what does the release of ADH cause?
    Triggered by a drop in BP/BV or a rist in blood osmolarity (increased blood concentration)

    Causes the kidneys to absorb more water, which results in (higher vascular volume, decreased urine output)
  13. What inhibits the release of antidiuretic hormone (ADH) and what does the inhibition of ADH cause?
    Inhibited by a rise in BP/BV or a drop in blood osmolarity (decreased concentration)

    Inhibition causes the kidneys to excrete more water in the urine, which results in lower vascular volume and high urinary output of dilute urine
  14. What happens in the body when hypervolemia occurs?
    • ECF volume increased
    • Increase in BV and atrial distention
    • Increased ANP release
    • Decreased aldosterone/ADH release, decreased thirst
    • Increased Na+/water loss
    • homeostatsis restored
  15. What happens in the body when hypovolemia occurs?
    • ECF volume decreases (fluid/sodium loss)
    • Decrease in BV/BP
    • Increasted renin secretion and angiotensin II activation
    • Increased aldosterone/ADH release
    • Increased Na+/water retention, increased thirst
    • Homeostasis restored
  16. What happens when hypernatremia occurs?
    • Increased concentration of Na+ in the ECF
    • Osmoreceptors stimulated
    • Increased ADH release, increased thirst
    • Decreased urinary water loss, increased water gain
    • Additional water dilutes ECP, volume increased
    • Homeostasis restored
  17. What happens when hyponatremia occurs?
    • Decreased Na+ concentration in the ECF
    • Osmoreceptors inhibited
    • Decreased thirst/ADH release
    • Increased urinary water loss, decreased water gain
    • Water loss concentrates ECF, volume reduced
    • Homeostasis restored
  18. What are the main purposed of fluid therapy?
    • Isotonic: to increase ECF
    • Hypotonic: to increase ECF and rehydrate
    • Hypertonic: to dehydrate cells
    • Colloid: to increase plasma volume
  19. What is osmosis and how does it work?
    Water moves by the concentration gradient from an area of high concentration to low concentration
  20. What is diffusion and how does it work?
    The electrolytes more from an area of high concentrattion to low concentration
  21. What is the concentration of sodium in the blood?
    0.9% (isotonic)
  22. Hypertonic vs. Hypotonic
    Hypertonic: there is more salt in the solution than there is in the body (ie. 3% NS in an IV bag)

    Hypotonic: there is less salt in the solution than there is in the body (ie. 0.3% NS in an IV bag)
  23. What are 3 examples of an isotonic solution?
    • Normal saline (NS)
    • Ringers solution
    • Lactated ringer's(LR)
  24. What does a hypotonic solution do and what is an example?
    • Has a lower osmolarity than normal plasma
    • Pulls water out of the vessels into the cells
    • Results in decreased vascular volume

    ie. D5W or 0.45% NS
  25. What is a hypertonic solution, what is it used for, and what is an example?
    A hypertonic solution has a higher osmolarity than normal plasma, so water is pulls from the cells into the vessels

    Used to promote osmotic diuresis (rarely used; can be used for cerebral edema and to decrease intercranial pressure)

    Example: 10% dextrose, 5% NS
  26. What are colloids and what is an example of one?
    Colloids are large solute particles that are volume expanders

    Ie. Albumin (pulls fluid in and promotes osmosis into the vascular system)
  27. What could cause a fluid volume deficit?
    • Isotonic fluid loss
    • Hypertonic dehydration
    • Third-spacing (ascites)
  28. What could cause a fluid volume excess?
    • Isotonic fluid excess
    • Hypotonic fluid excess
    • Synrom of inappropriate ADH (SIADH)
    • Polydypsia
  29. How do the kidneys compensate for acidosis vs. alkalosis?
    Acidosis: increased hydroden secretion

    Alkalosis: bicarbonate and pH concentration in urine to rise
  30. An anion gap is...

    A low anion gap is caused by _______

    A high anion gap is caused by _______
    # Cations (-) # Anions= Anion Gap

    low= alkalosis

    high= acidosis

    *normal is 9-26 mEq/L

    *is commonly used in the diagnosis of metabolic acidosis
  31. Causes of metabolic acidosis (high, normal, and low)
    • High
    • anion gap:
    • DKA, starvation, lactic acidosis, renal failure

    • Normal anion gap:
    • Pancreatic/biliary fistulas, diuretics

    • Decreased anion gap
    • Hypermagnesemia
Card Set
Fluid Balance 2
Pharm 505