Fluid, Electrolyte, and Acid-Base Balance

Question 1

Body fluids are distributed in two distinct compartments. Briefly explain each one.

Answer 1

a. Extracellular: outside the cells (1/3 of total body water)
b. Intracellular: inside the cells (2/3 of total body water)

Question 2

Cations:

Answer 2

ions that are positively charged; sodium, potassium, calcium, and magnesium

Question 3

Anions:

Answer 3

ions that are negatively charged; chloride, and bicarbonate

Question 4

mmol/L:

Answer 4

represent the number of milligrams of the electrolyte divided by its molecular weight that are contained in a liter of the fluid being measured; (how labs report electrolyte measurements)

Question 5

osmosis -

Answer 5

process by which water moves through a membrane that separates fluids with different particle concentrations

Question 6

osmotic pressure -

Answer 6

an inward-pulling force caused by particles in the fluid

Question 7

osmolarity -

Answer 7

a measure of the number of particles per kilogram of water

Question 8

isotonic solution -

Answer 8

fluid with the same concentration of nonpermeant particles as normal blood

Question 9

hypertonic solution -

Answer 9

is more concentrated than normal blood

Question 10

hypertonic solution -

Answer 10

is more dilute than the blood

Question 11

diffusion -

Answer 11

passive movement of electrolytes or other particles down the concentration gradient (from areas of higher concentration to areas of lower concentration)

Question 12

filtration -

Answer 12

fluid moves into and out of capillaries (between the vascular and interstitial compartments)

Question 13

List the three processes that maintain fluid homeostasis.

Answer 13

A fluid intake and absorption
B fluid distribution
C fluid output

Question 14

Define how antidiuretic hormone (ADH) regulates fluid balance.

Answer 14

ADH regulates the osmolarlity of the body of fluids by influencing how much water is excreted in the urine. More ADH is released if body fluids become more concentrated. Factors that increase ADH levels: severely decreased blood volume (dehydration, hemorrgage), pain, stressors, and some medications. ADH levels decrease if body fluids become too dilute. This allows more water to be excreted in urine, creating a larger volume of dilute urine and concentrating the body fluids back to normal osmolality. (example, alcohol decreases ADH release, and when people drink they urinate frequently.)

Question 15

Changes in renal perfusion initiate the renin-angiotension-aldosterone mechanism. Explain the mechanism.

Answer 15

RAAS regulates extracellar fluid volume by influencing how much sodium and water are excreted in urine.

Question 16

Angiotension I:

Answer 16

Renin converts angiotensionogen to angiotensin I, which other enzymes in the lung capillaries convert to angiotensin II.

Question 17

Angiotension II:

Answer 17

has several functions, vasoconstriction in some vascular beds. The important fluid homeostatsis function of angiotensin II includes stimulation of aldosterone release form the adrenal cortex

Question 18

aldosterone

Answer 18

circulates to the kidneys where it causes resorption of sodium and water in isotonic proportion in the distal renal tubules. Removing sodium and water from the renal tubules and retuning it to the blood increases the volume of the extracellular fluid. Contributes to electrolyte and acid base balance by increasing urinary excretion of potassium and hydrogen ions

Question 19

What is atrial natriuretic peptide?

Answer 19

Regulates ECV by influencing how much sodium and water are excreted in the urine; so opposes the effect of aldoesterone

Question 20

Potassium

Answer 20

3.5 – 5.0 mEq/L; Maintains resting membrane potential of skeletal, smooth, and cardiac muscle, allowing for normal muscle function

Question 21

Calcium

Answer 21

9.0 – 10.5; Influences excitability of nerve and muscle cells; necessary for muscle contraction

Question 22

Magnesium

Answer 22

1.5 – 2.5; Influences function of neuromuscular junctions and is a cofactor for numerous enzymes

Question 23

Phosphate

Answer 23

2.5 – 4.5 Necessary for production of ATP, the energy source for cellular metabolism

Question 24

Extracellular fluid volume deficit:

Answer 24

insufficient isotonic fluid in the extracellular compartment

Question 25

Extracellular fluid volume excess:

Answer 25

too much isotonic fluid in the extracellular compartment

Question 26

Hypokalemia labs

Answer 26

Serum K+ levels less than 3.5 mEq/L , possible ECG abnormalities

Question 27

Hypokalemia s&s

Answer 27

Bilateral muscle weakness that begins in quadriceps and may ascend to respiratory muscles, abdominal distention, decreased bowel sounds, constipation, cardiac dysrhythmias, signs of digoxin toxicity at normal digoxin levels

Question 28

Hyperkalemia labs

Answer 28

Serum K+ level greater than 5 mEq/L possible ECG abnormalities

Question 29

Hyperkalemia s&s

Answer 29

Bilateral muscle weakness that begins in quadriceps, transient abdomical craps and diarrhea, cardiac dysrhythmias, cardiac arrest

Question 30

Hypocalcemia labs

Answer 30

Total serum Ca 2+ less than 8.4 mg/dL or serum ionized Ca2+ levels less than 4.5 mg/dL; ECG abnormalities possible

Question 31

Hypocalcemia s&s

Answer 31

Positive chvostek’s sign, positive trousseau’s sign and circumoral region, hyperactive reflexes, muscle twitching and cramping, tetany, seizures, larygospams, cardiac dyrhythmias

Question 32

Hypercalcemia labs

Answer 32

Total serum Ca 2+ less than 10.5 mg/dL or serum ionized Ca2+ greater than 5.3 mg/dL; ECG abnormalities possible

Question 33

Hypercalcemia s&s

Answer 33

Anorexia, N&V, constipation, fatigue, diminished reflexes, lethargy, decreased level of consciousness, confusion, personality change, cardiac dysrhythmias; possible flank pain from renal calcuil; shift of calcium from bone, pathological fractures; signs of digoxin toxicity at normal digoxin levels

Question 34

Hypomagnesemia labs

Answer 34

Serum Mg2+ level less than 1.5 mEq/L

Question 35

Hypomagnesemia s&s

Answer 35

Positive Chvostek’s and Trousseau’s signs, hyperactive deep tendon reflexes, insomia, muscle cramps and twitching, grimacing, dysphagia, tachycardia, hypertension, tetany, seizures, cardiac dysrhythmias; signs of digoxin toxicity at normal digoxin levels

Question 36

Hypermagnesemia labs

Answer 36

Serum Mg2+ level greater 2.5 mEq/L; ECG abnormalities possible

Question 37

Hypermagnesemia s&s

Answer 37

Lethargy, hypoactive deep tendon reflexes, bradycardia, hypotension, acute elevation in magnesium levels; flushing, sensation of warmth; severe hypermagnesemia; flaccid muscle paralysis, decreased reate and depth of respirations and cardiac dysrhythmias, cardiac arrest