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Questions and Answers
What is one major cause of potassium excess related to renal function?
What is one major cause of potassium excess related to renal function?
Which condition is known to increase extracellular fluid potassium concentration?
Which condition is known to increase extracellular fluid potassium concentration?
What symptom might a patient experience due to potassium excess related to neuromuscular excitability?
What symptom might a patient experience due to potassium excess related to neuromuscular excitability?
Which treatment option is used to redistribute potassium from the extracellular fluid into the intracellular fluid?
Which treatment option is used to redistribute potassium from the extracellular fluid into the intracellular fluid?
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Metabolic acidosis is characterized by a decrease in which of the following?
Metabolic acidosis is characterized by a decrease in which of the following?
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What is a common cause of acute lactic acidosis?
What is a common cause of acute lactic acidosis?
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Which of the following medications can cause hyperkalemia by sparing potassium?
Which of the following medications can cause hyperkalemia by sparing potassium?
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How does the body compensate for decreased pH in metabolic acidosis?
How does the body compensate for decreased pH in metabolic acidosis?
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What is the urine output and urine osmolality status in hypernatremia?
What is the urine output and urine osmolality status in hypernatremia?
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What is the defining serum potassium level for hypokalemia?
What is the defining serum potassium level for hypokalemia?
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Which of the following causes can lead to hypokalemia?
Which of the following causes can lead to hypokalemia?
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What physical symptoms can occur in severe hypokalemia?
What physical symptoms can occur in severe hypokalemia?
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What effect does insulin have on potassium levels?
What effect does insulin have on potassium levels?
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What is a common symptom of metabolic alkalosis associated with severe hypokalemia?
What is a common symptom of metabolic alkalosis associated with severe hypokalemia?
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Which of the following correctly describes hyperkalemia?
Which of the following correctly describes hyperkalemia?
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Which gastrointestinal symptom is associated with severe hypokalemia?
Which gastrointestinal symptom is associated with severe hypokalemia?
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What is the primary role of body fluids?
What is the primary role of body fluids?
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What are electrolytes primarily known for?
What are electrolytes primarily known for?
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How are cations differentiated from anions?
How are cations differentiated from anions?
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What is diffusion in the context of body fluids?
What is diffusion in the context of body fluids?
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Which describes osmosis?
Which describes osmosis?
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What does tonicity refer to in body fluids?
What does tonicity refer to in body fluids?
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Why are substances like glucose and urea classified as nonelectrolytes?
Why are substances like glucose and urea classified as nonelectrolytes?
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What happens when a positively charged hydrogen ion is exchanged?
What happens when a positively charged hydrogen ion is exchanged?
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What happens to respiratory rate during metabolic acidosis?
What happens to respiratory rate during metabolic acidosis?
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Which condition is a common cause of metabolic acidosis?
Which condition is a common cause of metabolic acidosis?
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How is metabolic alkalosis primarily defined?
How is metabolic alkalosis primarily defined?
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What can lead to the loss of fixed acids and contribute to metabolic alkalosis?
What can lead to the loss of fixed acids and contribute to metabolic alkalosis?
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Which treatment may be indicated for metabolic acidosis?
Which treatment may be indicated for metabolic acidosis?
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What is the relationship between Cl⁻ and HCO3⁻ in metabolic conditions?
What is the relationship between Cl⁻ and HCO3⁻ in metabolic conditions?
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Which medication can lead to metabolic alkalosis?
Which medication can lead to metabolic alkalosis?
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What is a common symptom of metabolic acidosis?
What is a common symptom of metabolic acidosis?
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Which conditions commonly accompany the development of metabolic alkalosis?
Which conditions commonly accompany the development of metabolic alkalosis?
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What is the primary serum pH level indicating metabolic alkalosis?
What is the primary serum pH level indicating metabolic alkalosis?
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Which neurologic sign is less frequently associated with metabolic alkalosis compared to other acid-base disorders?
Which neurologic sign is less frequently associated with metabolic alkalosis compared to other acid-base disorders?
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What is the consequence of severe metabolic alkalosis?
What is the consequence of severe metabolic alkalosis?
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What role does potassium chloride play in the treatment of metabolic alkalosis?
What role does potassium chloride play in the treatment of metabolic alkalosis?
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What is respiratory acidosis primarily characterized by?
What is respiratory acidosis primarily characterized by?
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Which of the following can cause acute respiratory acidosis?
Which of the following can cause acute respiratory acidosis?
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In patients with chronic lung disease, what effect does oxygen therapy have?
In patients with chronic lung disease, what effect does oxygen therapy have?
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Study Notes
Fluids and Electrolytes
- Fluids and electrolytes are present in body cells, the tissue spaces between the cells, and in the blood that fills the vascular compartment.
- Body fluids transport gases, nutrients, and wastes; help generate the electrical activity needed to power body functions; take part in the transforming of food into energy; and otherwise maintain the overall function of the body.
Introductory Concepts
- Electrolytes are substances that dissociate in solution to form charged particles, or ions. For example, a sodium chloride (NaCl) molecule dissociates to form a positively charged Na and a negatively charged Cl ion.
- Particles that do not dissociate into ions, such as glucose and urea, are called nonelectrolytes.
- Positively charged ions are called cations because they are attracted to the cathode of a wet electric cell, and negatively charged ions are called anions because they are attracted to the anode.
- Cations and anions may be exchanged for one another, providing they carry the same charge. For example, a positively charged hydrogen ion (H+) may be exchanged for a positively charged K+ and a negatively charged bicarbonate ion (HCO3-) may be exchanged for a negatively charged chloride ion (Cl-).
- Diffusion is the movement of charged or uncharged particles along a concentration gradient.
- Osmosis is the movement of water across a semipermeable membrane (i.e., one that is permeable to water but impermeable to most solutes).
- Tonicity refers to the tension or effect that the effective osmotic pressure of a solution with impermeable solutes exerts on cell size because of water movement across the cell membrane.
Hypernatremia
- Hypernatremia refers to an increase in serum sodium levels above 145 mEq/L (145 mmol/L).
- Hypernatremia is often associated with an increase in serum osmolality.
- Serum osmolality is a measure of the total number of dissolved particles, or solutes, in the serum.
- Causes of hypernatremia include:
- Inadequate intake of free water.
- Excessive loss of water such as from fever, sweating, diarrhea, or diabetes insipidus
- Excessive administration of sodium.
- Manifestations of hypernatremia include:
- Thirst
- Lethargy
- Confusion
- Seizures
- Coma
- Urine output is decreased, and urine osmolality is increased because of renal water-conserving mechanisms.
- Body temperature frequently is elevated, and the skin becomes warm and flushed.
Hypokalemia
- Hypokalemia refers to a decrease in serum potassium levels below 3.5 mEq/L (3.5 mmol/L).
- Causes of hypokalemia include:
- Inadequate intake.
- Excessive gastrointestinal, renal, and skin losses.
- Redistribution between the ICF and ECF compartments.
- A wide variety of adrenergic agonist drugs (e.g., decongestants and bronchodilators) shift potassium into cells and cause transient hypokalemia.
- Insulin also increases the movement of potassium into the cell. Because insulin increases the movement of glucose and potassium into cells, potassium deficit often develops during treatment of diabetic ketoacidosis.
- The signs and symptoms of potassium deficit seldom develop until serum potassium levels have fallen to less than 3.0 mEq/L (3.0 mmol/L).
- Signs and Symptoms of Hypokalemia
- Urine output and plasma osmolality are increased, urine specific gravity is decreased, and complaints of polyuria, nocturia, and thirst are common.
- Metabolic alkalosis and renal chloride wasting are signs of severe hypokalemia.
- Atony (loss of tone) of the gastrointestinal smooth muscle cause constipation, abdominal distention, and, in severe hypokalemia, paralytic ileus.
- Electrocardiographic (ECG) changes.
- Muscle paralysis with life-threatening respiratory insufficiency can occur with severe hypokalemia.
Hyperkalemia
- Hyperkalemia refers to an increase in serum levels of potassium in excess of 5.0 mEq/L (5.0 mmol/L).
- It seldom occurs in healthy persons because the body is extremely effective in preventing excess potassium accumulation in the extracellular fluid.
- The three major causes of potassium excess are:
- Decreased renal elimination
- Movement of potassium from the ICF to ECF compartment
- Excessively rapid rate of administration
- Other Causes:
- Chronic kidney disease
- Acidosis also increases ECF potassium concentration
- A decrease in aldosterone-mediated potassium elimination
- Potassium-sparing diuretics can produce hyperkalemia
- The signs and symptoms of potassium excess are closely related to a decrease in neuromuscular excitability.
- Signs and Symptoms of Hyperkalemia
- Generalized muscle weakness or dyspnea secondary to respiratory muscle weakness
- ECG changes
Management of Hyperkalemia
- Calcium antagonizes the potassium-induced decrease in membrane excitability, restoring excitability toward normal.
- The redistribution of potassium from the ECF into the ICF compartment can be accomplished by the administration of sodium bicarbonate, B-agonists (e.g., nebulized albuterol), or insulin to rapidly decrease the ECF concentration.
- Intravenous infusions of insulin and glucose may also be used for this purpose.
Metabolic Acidosis
- It involves a decreased serum HCO3- concentration along with a decrease in pH.
- In metabolic acidosis, the body compensates for the decrease in pH by increasing the respiratory rate in an effort to decrease PCO2 and H2CO3 levels.
- Metabolic acidosis can be caused by one or more of the following four mechanisms:
- Increased production of fixed metabolic acids or ingestion of fixed acids such as salicylic acid.
- Decreased renal excretion of fixed acids such as occurs in renal failure or with the use of drugs such as acetazolamide.
- Loss of HCO3- from the body such as occurs in diarrhea or with ileostomy drainage.
- An increased serum Cl-concentration.
- Causes of Metabolic Acidosis include
- Lactic acid
- Ketoacids
Lactic Acid
- Most cases of lactic acidosis are caused by inadequate oxygen delivery, as in shock or cardiac arrest.
Hyperchloremic Acidosis
- Hyperchloremic acidosis occurs when Cl- levels are increased.
- Because Cl- and HCO3- are exchangeable anions, an increase in one will lower the other.
Manifestations of Metabolic Acidosis
- Metabolic acidosis is characterized by a decrease in serum pH (7.35).
- Acidosis typically produces a compensatory increase in respiratory rate with a decrease in PCO2.
- The signs & symptoms of metabolic acidosis include alterations in cardiovascular, neurologic, and musculoskeletal function resulting from the decreased pH.
- With diabetic ketoacidosis, which is a common cause of metabolic acidosis, there is an increase in blood and urine glucose and a characteristic smell of ketones to the breath.
Treatment of Metabolic Acidosis
- The use of supplemental sodium bicarbonate (NaHCO3) may be indicated in the treatment.
Metabolic Alkalosis
- Metabolic alkalosis is a systemic disorder caused by an increase in serum pH due to a primary excess in HCO3.
- It is caused by loss of gastric hydrochloric acid (e.g., prolonged vomiting), loss of potassium or chloride, and administration of alkali such as sodium bicarbonate and citrate.
- Metabolic alkalosis can be caused by
- A gain of base via the oral or intravenous route.
- Loss of fixed acids.
- Maintenance of the increased bicarbonate levels.
Causes of Metabolic Alkalosis
- Oral ingestion of bicarbonate-containing antacids (e.g., Alka-Seltzer) or intravenous infusion of NaHCO3 or base equivalent (e.g., lactate in Ringer lactate, and citrate in blood transfusions).
- The loss of fixed acids occurs mainly through the loss of acid from the stomach and through the loss of chloride in the urine.
- Bulimia nervosa with self-induced vomiting also is associated with metabolic alkalosis.
- The loop and thiazide diuretics are commonly associated with metabolic alkalosis, the severity of which varies directly with the degree of diuresis
Manifestations of Metabolic Alkalosis
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Metabolic alkalosis is characterized by a serum pH above 7.45.
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Persons with metabolic alkalosis often are asymptomatic or have signs related to ECF volume depletion or hypokalemia.
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Neurologic signs and symptoms (e.g., hyperexcitability) occur less frequently with metabolic alkalosis than with other acid-base disorders because HCO3 enters the cerebrospinal fluid (CSF) more slowly than CO2.
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Metabolic alkalosis also leads to a compensatory hypoventilation with development of various degrees of hypoxemia and respiratory acidosis.
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Significant morbidity occurs with severe metabolic alkalosis, including respiratory failure, arrhythmias, seizures, and coma.
Treatment of Metabolic Alkalosis
- Potassium chloride is used as a therapy, the Cl- anion replaces the HCO3- anion and the K+ corrects the potassium deficit, allowing the kidneys to retain H+ while eliminating K+.
Respiratory Acidosis
- It is also known as hypercapnia, its characterized by a sustained increase in arterial PCO2, resulting in renal adaptation with a more marked increase in plasma HCO3 & lesser decrease in pH.
Causes of Respiratory Acidosis
- Acute disorder of ventilation.
- Chronic disorders of ventilation
- Acute respiratory acidosis can be caused by impaired function of the respiratory center in the medulla (as in narcotic overdose), lung disease, chest injury, weakness of the respiratory muscles, or airway obstruction.
- Patients with chronic lung disease who receive oxygen therapy at a flow rate that is sufficient to raise their PO2 to a level that produces a decrease in ventilation.
- In these persons, the medullary respiratory center has adapted to the elevated levels of CO2 and no longer responds to increases in PCO2.
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Description
Explore the fundamental concepts of fluids and electrolytes in the human body. This quiz delves into the roles of body fluids, the importance of electrolytes, and their dissociation into ions. Test your knowledge on how these elements contribute to maintaining overall bodily functions.
