The Cellular Environment - Chapter 3 Flashcards

Vocabulary flashcards covering key fluid, electrolyte, and acid-base concepts from Chapter 3: The Cellular Environment.

Starling Hypothesis

The law describing fluid movement across capillary membranes, defined as $\text{Net filtration} = \text{forces favoring filtration} - \text{forces opposing filtration}$.

Forces Favoring Filtration

Pressures that push fluid out of the capillary into the interstitial space, consisting of capillary hydrostatic pressure (blood pressure) and interstitial oncotic pressure.

Forces Favoring Reabsorption

Pressures that pull or hold fluid inside the capillary, consisting of plasma oncotic pressure and interstitial hydrostatic pressure.

Edema

The accumulation of fluid in the interstitial space caused by a plasma-to-interstitial fluid shift due to elevated hydrostatic pressure, decreased plasma oncotic pressure, elevated interstitial oncotic pressure, or lymphatic obstruction.

Sodium ($\text{Na}^+$)

The primary extracellular fluid (ECF) cation with a normal range of $135\text{-}145\,mEq/L$, responsible for regulating osmotic forces, acid-base balance, neuromuscular irritability, and cellular reactions.

Chloride ($\text{Cl}^-$)

The primary extracellular fluid (ECF) anion with a normal range of $96\text{-}106\,mEq/L$ that provides electroneutrality in relation to sodium.

Isotonic Alterations

Changes in total body water accompanied by a proportional change in electrolyte concentration, resulting in conditions like isotonic volume depletion or isotonic volume excess.

Osmotic Demyelination Syndrome

A severe neurological complication that can occur as a result of correcting hyponatremia too rapidly.

Potassium ($\text{K}^+$)

The major intracellular cation with a normal range of $3.5\text{-}5.0\,mEq/L$, maintained by the $\text{Na}^+/\text{K}^+$ pump, essential for nerve impulse conduction, cardiac rhythms, and muscle contraction.

Calcium ($\text{Ca}^{2+}$)

An essential element mostly stored in bone as hydroxyapatite, regulated by parathyroid hormone (PTH), vitamin D, and calcitonin, and required for nerve impulse transmission, myocardial contraction, muscle contraction, and blood clotting.

Phosphate ($\text{HPO}_4^{2-}$)

An anion primarily located in bone ($85\%$) necessary for high-energy ATP and creatine phosphate bonds, which maintains an inverse relationship with calcium defined by $\text{Ca}^{2+} \times \text{HPO}_4^{2-} = K$.

Magnesium ($\text{Mg}^{2+}$)

An intracellular cation with a normal value of $1.3\text{-}2.0\,mEq/L$ that functions as a cofactor in protein/nucleic acid synthesis, is required for ATPase activity, and decreases acetylcholine release at the neuromuscular junction.

Volatile Acids

Body acids, such as carbonic acid ($\text{H}_2\text{CO}_3$), that can be converted into and eliminated as carbon dioxide ($\text{CO}_2$) gas by the lungs.

Nonvolatile Acids

Metabolic acids such as sulfuric, phosphoric, and organic acids that cannot be eliminated by the lungs and must be excreted by the renal tubules with $\text{HCO}_3^-$ regulation.

Carbonic Acid-Bicarbonate Pair

The major plasma buffering system operating in the lungs and kidneys that maintains a standard ratio of $20:1$ bicarbonate to carbonic acid at a normal pH of $7.4$.

Compensation

The pH adjustment mechanism where the respiratory or renal systems adjust bicarbonate and carbonic acid levels to restore the normal $20:1$ ratio and normalize arterial pH.

Respiratory Acidosis

An acid-base disorder characterized by an arterial pH of $<7.35$ and an elevation of $\text{pCO}_2$ caused by alveolar hypoventilation or respiratory failure.

Respiratory Alkalosis

An acid-base disorder characterized by an arterial pH of $>7.45$ and a depression of $\text{pCO}_2$ caused by alveolar hyperventilation.

Metabolic Acidosis

An acid-base disorder characterized by an arterial pH of $<7.35$ due to a primary reduction in $\text{HCO}_3^-$ or an accumulation of noncarbonic acids.

Metabolic Alkalosis

An acid-base disorder characterized by an arterial pH of $>7.45$ due to an elevation of $\text{HCO}_3^-$, typically resulting from excessive loss of metabolic acids.

Anion Gap

A measurement reflecting the balance between cations and anions in blood serum, calculated as $(\text{Na}^+ + \text{K}^+) - (\text{Cl}^- + \text{HCO}_3^-)$, with a normal threshold value of $<16\,mEq/L$.

SLUMPED

An acronym representing causes of a widened anion gap metabolic acidosis: Salicylates, Lactic acidosis, Underfed/uremia, Methanol, Paraldehyde, Ethanol/ethylene glycol, and DKA.

ROME Mnemonic

A rule for reading arterial blood gases stating Respiratory is Opposite (Alkalosis: $\uparrow\text{pH}, \downarrow\text{PaCO}_2$; Acidosis: $\downarrow\text{pH}, \uparrow\text{PaCO}_2$) and Metabolic is Equal (Acidosis: $\downarrow\text{pH}, \downarrow\text{HCO}_3^-$; Alkalosis: $\uparrow\text{pH}, \uparrow\text{HCO}_3^-$).