Electrolytes

What is the total body water for males and females?

60 and 50% respectively

Of the total body water percentage, what percent makes up the intracellular fluid and what percent makes up the extracellular fluid?

ICF = 40%

ECF = 20%

What is extracellular fluid?

includes the plasma volume and interstitial fluid (surrounding cells)

What electrolytes do we see in ECF?

Na, Cl, HCO3

What is intracellular fluid?

Fluid within the cells

What electrolytes do we see in ICF?

K, Mg, PO4, and Na

What are electrolytes?

Ions that carry a charge

What are some electrolyte functions?

body hydration, enzyme activation, pH blood maintenance, coagulation factors, and bone stability

What is the most abundant extracellular cation?

Na

What are the main functions of sodium?

To maintain osmolality, or ECF volume

To transmit nerve pulses

In serum, how is sodium regulated (what two hormones)?

ADH (anti-diuretic hormone) and RAAS (renin-angiotensin aldosterone system)

Explain the general process of RAAS and how it increases blood pressure and blood volume.

1. If BP, BV, or sodium levels in serum are low, then renin is produced in the kidneys

2. Renin causes conversion of angiotensinogen into angiotensin I

3. Angiotension I converts to II with ACE enzymes in the lungs

4. Angiotensin II influences aldosterone production, increases vasoconstriction, and releases ADH from brain

5. aldosterone influences resorption of sodium from the kidneys, and excretes potassium

6. resorption of sodium and vasoconstriction increases BP or BV

Where is renin produced?

juxtaglomerular cells

What is the function of renin?

convert angiotensinogen into angiotensin I

Where is angiotensinogen produced?

Liver

What is the function of the ACE enzyme? Where is it produced?

converts angiotensin I to II, comes from the lungs

What is the function of aldosterone? Where is it produced?

To regulate sodium and potassium levels in serum

made in the adrenal gland

What is the function of ADH (vasopressin)? Where is it produced?

To maintain water volume, made in the brain

When is ADH produced and what are its functions?

Produced when plasma osmolality increases

Fx: decreases urine output, decreases sweating, and increases BP/BV

When aldosterone increases, what happens to the levels of sodium and potassium?

sodium resorption increases, potassium excretion increases

What is hyponatremia?

Decreased sodium in the blood

What are the causes of hyponatremia?

poor diet, diuretics, water overload, and syndrome of inappropriate ADH (SIADH)

What is the sodium concentration for hyponatremia?

<135 mEq/L

What is depletional hyponatremia?

When there is decreased ECF volume and sodium

What is dilutional hyponatremia?

When there is increased ECF volume and decreased sodium

What is SIADH? What does it stand for and what can it cause?

Syndrome of inappropriate ADH is where a tumor on the pituitary gland overproduces ADH

• increased ADH levels causes increased water retention (or dec. urine output), sweating, edemas in the brain

What is hypernatremia?

Increased sodium in the blood

What is the sodium concentration of hypernatremia?

<145 mEq/L

What causes hypernatremia?

sodium-poor body fluids, sodium overloading, and decreased ADH

What is the major intracellular electrolye?

Potassium

What are the functions of potassium in ICF?

regulates neuromuscular junctions, cardiac muscle contractions, and controls pH of arterial blood

What is hypokalemia?

Decrease of potassium in the blood

What is the concentration of potassium in hypokalemia?

<3.5 mmol/L

What causes hypokalemia?

Decreased dietary intake, drug use, insulin therapy (sequestered into cells), loss of body fluid, and increased aldosterone

What is hyperkalemia?

Increased potassium in the blood

What is the concentration of potassium in hyperkalemia?

>5.5 mmol/L

What are causes of hyperkalemia?

excess potassium intake, adrenal gland failure, low aldosterone, tissue damage, renal failure

What is the major extracellular anion?

Chloride

What is the function of chloride in the ECF?

Maintain osmotic pressure and electrical neutrality of RBCs

What is hypochloremia? What can cause this?

Decreased chloride in the blood, caused by chronic pyelonenephritis

What is hyperchloremia? What can cause this?

Increased chloride in the blood, caused by dehydration

For hypo and hyperkalemia, what are the most severe consequences?

Hypo: cardiac dysrhythmias

Hyper: cardiac arrhythmias

What is the second most abundant extracellular anion?

bicarbonate

What are the functions of bicarbonate in ECF?

act as a buffer and maintain electrical neutrality

When there is decreased bicarbonate in the blood, what is the condition called?

metabolic acidosis

When there is increased bicarbonate in the blood, what is the condition called?

metabolic alkalosis

What is the anion gap?

the measurement of the acid/base balance in the body

Why is the anion gap clinically significant?

It assesses the cause of metabolic acidosis based on the gap value

• If there is a normal AG, then the initial cause is loss of bicarbonate

• If there is an increased AG, then the initial cause is presence of organic acids

What is the normal value for AG?

8-12

What is the formula of AG?

Na - (Cl + HCO3) = AG