Fluid and Electrolytes

Question 1

Electrolyte

Answer 1

An element or compound that, when dissolved or dissociated in water or solvent, separates into ions

Question 2

Ions

Answer 2

Cations: positively charged (Na+, K+, Ca²+)
Anions: negatively charged (Clˉ, HCO3ˉ, SO4ˉ)

Question 3

Osmolality

Answer 3

is a measure of the solute concentration per kg in a solution.

Question 4

Solute

Answer 4

is a substance dissolved in a solvent

Question 5

Solvent

Answer 5

is a substance that is capable of dissolving a solute (liquid or gas).

Question 6

Tonicity

Answer 6

is the tension or effect that the osmotic pressure of a solution with impermeable solutes exerts on cell size due to water movement across the cell membrane.

Question 7

Hypertonic

Answer 7

Solutes move out of the cell, having a higher osmotic pressure than a particular fluid.

Question 8

Hypotonic

Answer 8

Solutes move into the cell, having a lower osmotic pressure than a particular fluid.

Question 9

Capillary permeability

Answer 9

the movement of fluid
components (i.e. electrolytes, glucose, minerals)
between organs & between cells.

Movement depends on the ability of the cell membrane to allow the passage of fluid components with in the vascular system.

Occurs because of osmosis, diffusion, filtration, or active transport

Question 10

Osmosis

Answer 10

Movement of water across a semipermeable membrane from an area of lesser to one of greater concentration

Water moves into the vascular compartment/intracellular space from extracellular space

Question 11

Diffusion

Answer 11

Random movement of a solute through a semipermeable membrane from higher to lower concentration

Question 12

Capillary Filtration

Answer 12

Movement of water through capillary pores due to mechanical forces

Question 13

Active Transport

Answer 13

Movement of ions against their concentration gradient. Requires energy

Question 14

Filtration & Hydrostatic pressure

Answer 14

Venous side should have lower hydrostatic pressure
Chronic hypertension can cause edema in interstitial space
Colloid osmotic pressure contains protein (less in people with renal disease, with edema)

Question 15

Hydrostatic Pressure

Answer 15

Fluid pushing force inside the capillary

Inside capillaries hydrostatic pressure and capillary filtration pressure are equal

Question 16

Colloidal Osmotic Pressure

Answer 16

Pulling force created by particles (i.e. plasma proteins) that do not pass through capillary pores
Capillary colloidal pressure is greater than interstitial colloidal pressure

Question 17

Lymph Drainage

Answer 17

Return of fluids and osmotically active plasma proteins from interstitium into the lymphatic system to return to circulation

Question 18

Factors Causing Edema

Answer 18

Increased capillary filtration pressure
Decreased capillary colloidal osmotic pressure
Increased capillary permeability
Obstruction of lymph flow: mastectomy/impaired lymphatic drainage

What does an increased _____ pressure cause? How does edema form?
Anasarca: edema throughout the body. Can be caused by capillary osmotic pressure?
> Blood volume = higher capillary filtration pressure

Question 19

Regulation of Body Fluids

Answer 19

Fluid intake: Thirst-control center: the hypothalamus
Intake is about 2200 to 2700 ml/day (2-3 L)

Hormone Regulation: Antidiuretic hormone (ADH) Renin-angiotensin-aldosterone mechanism
Atrial natriuretic peptide: release fluid to prevent edema

Fluid Output: Fluid is lost through kidneys, skin, lungs (humidity, increasing respiratory rate), and GI tract
Insensible loss: increasing respiratory rate

maintain homeostasis

Question 20

Cations

Answer 20

Sodium (Na+)
Potassium (K+)
Calcium (Ca2+)
Magnesium (Mg2+)

Question 21

Anions

Answer 21

Chloride (Cl-)
Bicarbonate (HCO3–)
Phosphate (PO43-)

Question 22

Sodium (Na+)

Answer 22

135-145 mEq/L
- the most abundant cation in ECF
- functions: maintain water balance, nerve
impulse transmission, regulate acid-base
balance, and participate in cellular
chemical reactions.
- regulated by dietary intake & aldosterone
secretion

Question 23

Antidiuretic Hormone (ADH)

Answer 23

AKA: vasopressin (stimulates arterial vasoconstriction)
Levels controlled by ECF volume and osmolality
High osmolality = High ADH, Hypernatremia
Some conditions favor abnormal increases in ADH (tumors). Swollen, hyponatremic
ETOH (alcohol) inhibits ADH

Question 24

Hyponatremia

Answer 24

< 135 mEq/L
Causes: sodium loss (GI, renal, & skin losses: sweating);
pshychogenic
polydipsia (drinking water increase); water intoxication; SIADH (Excess ADH)

Question 25

S/S of Hyponatremia

Answer 25

lethargy, edema, headache, disorientation, seizures, coma.

Pure Na loss: hypovolemia
Dilutional: Hypervolemia

Question 26

Hypernatremia

Answer 26

> 145mEq/L
Causes: Excess salt intake, aldosterone secretions, Diabetes Insipidus, increased sensible & insensible water loss, water deprivation (hypertonic/hypernatremic)

Question 27

S/S of Hypernatremia

Answer 27

thirst, dry & flushed skin, dry & sticky m.m., postural hypotension, fever, CNS: agitation, decreased reflexes, convulsions, restlessness, & irritability.

Question 28

If you were walking across the Sahara Desert with an empty canteen, the amount of ADH secreted would most likely:

Answer 28

increase. (High plasma osmolality, hypernatremia, hypertonic)
Because your body would probably be dehydrated, it would try to retain as much fluid as possible. To retain fluid, ADH secretion increases.

Question 29

If you placed two containers next to each other, separated only by a semipermeable membrane, and the solution in one container was hypotonic relative to the other, fluid in the hypotonic container would:

Answer 29

move out of the hypotonic container into the other.
Fluid would move out of the hypotonic container
into the other container to equalize the
concentration of fluid within the two containers.

Question 30

Potassium (K)

Answer 30

3.5 – 5 mEq/L
- principle cation in ICF compartment
- functions: transmission & conduction of
nerve impulses, normal cardiac
conduction, skeletal/smooth muscle
contraction, and regulates metabolic
activities.
- Regulated by dietary intake & renal
excretion.
Kidney failure: can’t excrete Potassium
Aldosterone: releases K into urine (moves out)
Insulin: K moves into cell

The ion for DIASTOLE

Question 31

Potassium’s role in the Acid-Base Balance

Answer 31

Acidosis- potassium shift occurs from the ICF to the ECF as hydrogen ions move into cells, aldosterone deficiency leads to hyperkalemia.

Alkalosis- potassium shift from ECF to ICF in exchange for hydrogen ions, thus lowering potassium in the ECF.

Question 32

Hypokalemia (K)

Answer 32

< 3.5 mEq/L
Causes: Use of K+ wasting diuretics (most), polyuria, GI losses (vomiting, diarrhea, NG/colostomy outputs), alkalosis, Tx of DKA with insulin.

S/S: Skeletal muscle weakness 
	U wave/ ECG changes (PR Interval increase)
	Constipation, ileus
	Toxic effects of digoxin
	Irregular, weak pulse
	Orthostatic hypotension
	Numbness (paresthesias)

Question 33

Hyperkalemia (K)

Answer 33

> 5 mEq/L
Causes: Renal failure, fluid volume deficit, massive cellular damage (burns & trauma), acidosis (esp DKA), rapid infusion of stored blood, use of K+-sparing diuretics, salt substitutes.

S & S: ECG changes (tall, tented T wave), paresthesias, muscle weakness, abdominal cramping, diarrhea.

Question 34

Calcium

Answer 34

8.5 – 10.5 mg/dL
- 50% bound to bound to albumin, 40%
free ionized, 10% in bone and teeth.
- functions: bone & teeth formation, blood
clotting, hormone secretion, cardiac conduction, nerve impulse transmission, & muscle contraction.
- PTH & Vitamin D responsible for maintaining
“Parathyroid pulls… Calcitonin keeps”

Question 35

Hypocalcemia

Answer 35

8.5 mg/dL
Causes: Rapid administration of blood containing citrate, hypoalbuminemia, hypoparathyroidism, vitamin D deficiency, alkalosis, pancreatitis, Chronic Renal Failure (Vitamin D not activated), chronic alcoholism

Question 36

S/S of Hypocalcemia

Answer 36

S & S: numbness & tingling of fingers and circumoral (around mouth) region, hyperactive reflexes, +Trousseau’s (nerve excitability/tetany of fingers during BP) & +Chvostek’s sign (Stroking cheek), muscle cramps, fractures (if chronic). ECG: prolonged ST & QT

Question 37

Hypercalcemia

Answer 37

10.5 mg/dL
Causes: Hyperparathyroidism, Cancer, Paget’s disease, osteoporosis, prolonged bed rest, thiazide diuretics

S/S: Anorexia, abdominal pain & constipation, muscle weakness, hypoactive reflexes, lethargy, flank pain (if kidney stones), ECG: shortened QT & ST segment

Question 38

Magnesium

Answer 38

1.5 – 2.5 mEq/L
the second most abundant cation in ICF
regulated by dietary intake, renal mechanisms, and actions of PTH.

Functions: enzyme reactions during carbohydrate metabolism, helps produce ATP, role in protein synthesis, and affects cardiac and skeletal muscle excitability.

Question 39

Hypomagnesemia

Answer 39

1.5 mEq/L
Causes: inadequate intake, inadequate absorption, excessive loss from GI tract or urinary system. Alcoholics.

Similar to hypocalemia… The 3 Ts (tremors, twitching, tetany) & hyperactive Deep Tendon Reflexes. Chvostek’s & Trousseau’s sign.

CNS irritation: lethargy, confusion, seizures. Dysrythmias, N/V

STARVED

Question 40

Hypermagnesemia

Answer 40

2.5 mEq/L
Causes: Renal failure, excessive intake.

S/S: hypoactive DTRs, weakness, drowsiness, decreased rate/depth of respirations, bradycardia, hypotension, flushing.

RENAL