Fluid and Electrolyte

Question 1

What are the 3 fluid compartments

Answer 1

extracellular
Intravascular(part of the extracellular)
intracellular

Question 2

Relative fluid distribution between extracellular and intracellular

Answer 2

Extracellular 1/3

Intracellular 2/3

Question 3

Major Extracellular Ion

Answer 3

Na+

Question 4

Minor Extracellular Ions

Answer 4

HCO3-
Cl-
Ca++

Question 5

Major Intracellular Ion

Answer 5

K+

Question 6

Minor Intracellular Ions

Answer 6

Mg++
HPO4-
Proteins-

Question 7

Avg. Fluid Concentration in body compartments

Answer 7

285-295 mOsm

Good estimate of mOsm is to find the sodium concentration and double it.

Question 8

Define Osmosis

Answer 8

movement of liquid (water) to equalize concentrations across a membrane.

Question 9

Define Hydrostatic Pressure

Answer 9

force of water/liquid across the membrane
(ie. blood pressure in peripheral circulation)
pressure gradient from aorta -> venacava

Question 10

Oncotic Pressure

Answer 10

Water movement/being drawn towards large solutes.

plasma proteins/albumin

Question 11

Diffusion

Answer 11

Movement of molecules (eg. Na+, Ca++) down their concentration gradient (chemical or electrical) Passive Process!

Question 12

Pressures at the arterial end

Answer 12

Hydrostatic Pressure > Oncotic Pressure

Net movement of fluid into the interstitial space

Question 13

Pressures at the venous end

Answer 13

Oncotic Pressure > Hydrostatic Pressure

Net movement of fluid into the vasculature

Question 14

Osmolality vs Osmolarity

Answer 14

Osmolality (mOsm/kg)
Osmolarity (mOsm/L)

since 1 L of water = 1kg relatively interchangeable for our applications.

Question 15

Serum Osmolality

Answer 15

= (2 x {Na + K}) + (BUN/2.8) + (glucose/18)

Question 16

Isotonic Overhydration (Hypervolemia)

Answer 16

• Gain of isotonic fluid (eg. 0.9 NS)
• Osmolality unchanged
• ICF volume (no change)
• ECF volume (high)

Question 17

What is RAAS

Answer 17

Renin-Angiotensin-Aldosterone_System

Question 18

Function of Renin

Answer 18

Angiotensinogen -> Angiotensin I coversion

Question 19

Function of ACE

Answer 19

Angiotensin I -> Angiotensin II conversion

Question 20

What does Angiotensin II do

Answer 20

Direct Vasoconstriction 
Aldosterone release (Na+ and H2O retention)
Sympathetic activity 
ADH release (H2O retention)

Question 21

What does Aldosterone do

Answer 21

Distal Tubule/Collecting Duct (Na+ absorption and K+ excretion)
H2O absorption follows Na+

Question 22

Isotonic Dehydration (Hypovolemia)

Answer 22

• Loss of Isotonic fluid (hemorrhage)
• Osmolality unchanged
• ICF volume (no change)
• ECF volume (low)

Question 23

Hypernatremia (Water Deficit)

Answer 23

• poor fluid/water intake (imobility)
• loss of hypotonic solutes (dilute urine, diabetes insipidus)
• Increased ECF osmolarity with subsequent fluid shift into the extra cellular space.

Question 24

Hypernatremia (overhydration)

Answer 24

Hypertonic IV solutions/Hyperaldosteronism
Increased ECF osmolarity with subsequent fluid shift into the extra cellular space.
ECF volume (high)

Question 25

Hyponatremia (Water Excess)

Answer 25

``` Excess water intake/water intoxication Hypotonic IV fluids (D5W, 1/2 NS) SIADH Decreased ECF osmolarity with subsequent fluid shift into the ICF Cells swell ```

Question 26

Hyponatremia (Dehydration)

Answer 26

Inadequate sodium intake/ excessive Na+ loss Decreased ECF osmolarity with subsequent fluid shift into the ICF cells swell

Question 27

What is a Cation

Answer 27

positive charged ion | Na+, K+, Ca++, H+

Question 28

What is an Anions

Answer 28

negative charged ions | Cl-, HCO3-

Question 29

Normal Serum Sodium (Na+)

Answer 29

135 - 145 mEq/L

Question 30

Physiological roles of Na+

Answer 30

- 90% of all ECF cations - water/osmotic balance regulation - nerve conduction/neuromuscular function - acid base balance - concentration gradient for membrane transport

Question 31

Hyponatremia Symptoms

Answer 31

Neuro: lethargy, headache, confussion, seizure, coma. Muscles: Cramps, weakness, fatigue Gastro: Nausea, vomiting

Question 32

Hypernatremia Symptoms

Answer 32

Neuro: Confusion, irritability, restlessness. Seizures (if severe Na+ increase) Thirst Fever/Flushed Skin

Question 33

Normal Serum Chlorine (Cl-)

Answer 33

97 - 105 mEq/L

Question 34

Physiological roles of Cl-

Answer 34

Provides electroneutrality, pairs with Na+ | Moves with Na+, also important in Acid-base balance.

Question 35

Hypochloremia Symptoms

Answer 35

(usuallu goes along with hyponatremia) | signs of alkalosis, Low Na+ or Low K+

Question 36

Hyperchloremia Symptoms

Answer 36

(usuallu goes along with hypernatremia) fluid retention tachypnea / tachycardia weakness, lethargy +++ most symptoms in hyperchloremic patients are due to associated accidosis++++

Question 37

Normal Serum Potassium K+

Answer 37

3.5 - 4.5 mEq/L | ICF 156 mEq/L

Question 38

Physiological roles of K+

Answer 38

cell membrane re-polirization intracellular fluid and ion balance neuromuscular transmission acid base balance (H+/K+ exchange)

Question 39

Fluctuation of serum K+

Answer 39

Insulin (K+ moves intracellulary, serum K+ decreases) Catecholomines, B agonists ( lowers serum K+) Acidosis (serum K+ increases)

Question 40

Hypokalemia Symptoms

Answer 40

Weakness/Flaccid Paralysis Postural Hypotention Arrhythmia (U wave), flat/absent P wave, PVC's

Question 41

Hyperkalemia Symptoms

Answer 41

>5.5 mEq/L Peaked T's, wide QRS, sinusoidal wave Bradycardia, heart block, cardiac arrest Cramps, Nausea, vomiting

Question 42

Normal serum Calcium (Ca++)

Answer 42

4.5 - 5.5 mEq/L or (9-10.5 mg/dl) | 99% of calcium stored in bone

Question 43

Normal serum Phosphate (HPO4-)

Answer 43

2.5 - 4.5 mg/dl inverse relationship with Ca++ 9 if one decreases the other increases.

Question 44

Normal serum Magnesium (Mg++)

Answer 44

1.8-2.4 mEq/L