Clinical Significance

Question 1

What is the major cation of the Extracellular Fluid (ECF)?

Answer 1

Sodium (Na+)
90%
Largely determines Osmolality of plasma

Question 2

What are the primary processes associated with Sodium (Na+)?

Answer 2

Intake of water in response to thirst
Excretion of water
Blood volume status

Question 3

How much of the filtered Sodium (Na+) is reabsorbed in the Proximal Tubule?

Answer 3

60% - 75%

Question 4

What is the term for Serum/Plasma Na+ being < 135mmol/L?

Answer 4

Hyponatremia

Question 5

What can caused decreased levels of Na+?

Answer 5

Increased Na+ loss
Increased water retention
Water imbalances
Vomiting, Diarrhea, Severe burns

Question 6

What do we see in patients with Acute Hyponatremia ( < 120mmol/L)?

Answer 6

Medical Emergency
Seizures, Coma, Respiratory Depression

Question 7

What is the term for Serum/Plasma Na+ > 150mmol/L?

Answer 7

Hypernatremia

Question 8

What can cause Hypernatremia?

Answer 8

Excess loss of water (Hypovolemia)
Decreased water intake
Increase in Na+ intake

Question 9

What happens with patients with a Serum Na+ > 160mmol/L?

Answer 9

A high mortality rate
60% - 75%

Question 10

What is the major Intracellular Cation inside the body?

Answer 10

Potassium (K+)

Question 11

What are the functions that K+ performs in the body?

Answer 11

Neuromuscular Excitability regulation
Heart Contraction
ICF Volume
H+ concentration

Question 12

What role does Aldosterstone have in K+ reabsorption?

Answer 12

Causes additional K+ to be secreted into urine
Na+ is exchanged

Question 13

What is the major player in determining K+ excretion?

Answer 13

Distal Tubule

Question 14

What are some factors that influence K+ distribution?

Answer 14

ATPase pump inhibition caused by: Hypoxia, Hypomagnesemia, Digoxin Overdose
Insulin promotes acute entry of K+
Catecholamines (Epinephrine)promote K+
Acidosis/Alkalosis

Question 15

What can happen with Uncontrolled Diabetes Mellitus in regards to K+?

Answer 15

Hyperosmolality
Water diffuses from cells carrying K+
Depletion of K+

Question 16

What is the term for Serum/Plasma K+ < 3.5mmol/L?

Answer 16

Hypokalemia

Question 17

What causes Hypokalemia?

Answer 17

GI or urinary loss of K+
Increased uptake of K+ by cells
reduced intake of K+ with the use of Diuretics

Question 18

What are symptoms of Hypokalemia?

Answer 18

Weakness, Fatigue, Constipation

Question 19

What is the term for Serum/Plasma > K+ 5.1mmol/L?

Answer 19

Hyperkalemia

Question 20

What is the most common cause of Hyperkalemia?

Answer 20

Therapeutic K+ administration

Question 21

What are symptoms of Hyperkalemia?

Answer 21

Mental Confusion, Weakness, fatigue, tingling, paralysis

Question 22

What causes Peripheral Vascular Collapse and Cardiac Arrest?

Answer 22

Prolonged Severe Hyperkalemia (> 7.0mmol/L)

Question 23

What is the major extracellular anion?

Answer 23

Chloride (Cl-)

Question 24

What is Cl- mostly involved in?

Answer 24

Osmolality maintenance
Blood volume
Electric neutrality

Question 25

How does Cl- maintain Electrical Neutrality?

Answer 25

Reabsorbed with Na+ (Rate limiter)
Chloride Shift

Question 26

What is the term given to Serum/Plasma Cl- < 98mmol/L?

Answer 26

Hypochloremia

Question 27

What causes Hypochloremia?

Answer 27

Prolonged Vomiting
Diabetic Ketoacidosis
Aldosterone Deficiency
Pyelonephritis

Question 28

What is the term given to Serum Plasma Cl- > 107mmol/L?

Answer 28

Hyperchloremia

Question 29

What can cause Hyperchloremia?

Answer 29

Excess loss of HCO3-
Renal Tubular Acidosis
Metabolic Acidosis

Question 30

What is the second most abundant anion in the ECF?

Answer 30

Bicarbonate (HCO3-)

Question 31

What is the major buffering system in the blood?

Answer 31

Bicarbonate

Question 32

HCO3- diffuses out of the cell in exchange for Cl- to maintain what?

Answer 32

Ionic Charge Neutrality

Question 33

How much HCO3- gets reabsorbed?

Answer 33

85% by Proximal Tubules
15% by Distal Tubules