Fluid and Electrolyte Balance

A comprehensive set of flashcards covering key concepts in fluid and electrolyte balance, suitable for exam preparation.

What percentage of water content do infants have?

Infants have 73% or more water content.

What is the typical body water content percentage for a healthy male?

A healthy male is approximately 60% water.

What is the body water content percentage for healthy females?

Healthy females have about 50% body water content.

What is the minimum body water content for the elderly?

The elderly have about 45% body water content.

Which two compartments make up total body fluid?

Intracellular Fluid Compartment (ICF) and Extracellular Fluid Compartment (ECF).

What fraction of body fluid volume is contained in the Intracellular Fluid Compartment?

The Intracellular Fluid Compartment contains 2/3 of the body's volume of fluid.

What fraction of body fluid volume is contained in the Extracellular Fluid Compartment?

The Extracellular Fluid Compartment contains 1/3 of the body's volume of fluid.

What are the main components of Extracellular Fluid Compartments?

Plasma and interstitial fluid.

What is the term for substances dissolved in water?

Solutes.

How are solutes classified?

Solutes are classified as nonelectrolytes and electrolytes.

What do nonelectrolytes do in water?

Nonelectrolytes do not dissociate in water.

Provide examples of nonelectrolytes.

Examples include glucose, lipids, creatinine, and urea.

How do electrolytes behave in water?

Electrolytes dissociate into ions in water.

What is one characteristic of ions in body fluids?

Ions conduct electrical current.

Why do electrolytes have greater osmotic power than nonelectrolytes?

Electrolytes' ability to dissociate into two or more ions gives them greater osmotic power.

What is NaCl when dissolved in water?

Sodium chloride disassociates into Na+ and Cl-.

What is the major cation found in extracellular fluid?

The major cation in ECF is Na+.

What are the major anions in intracellular fluid?

The major anion in ICF is HPO4 2–.

What is the primary characteristic that distinguishes extracellular and intracellular fluids?

Each compartment has a distinctive pattern of electrolytes.

How does fluid exchange occur between plasma and interstitial fluid?

Exchanges occur across capillary walls.

What happens to fluid at the arteriolar end of the capillary?

Fluid leaks from the arteriolar end of the capillary.

What picks up remaining fluid not reabsorbed by the capillaries?

Lymphatics pick up remaining fluid and return it to blood.

What regulates continuous exchange and mixing of fluids?

Osmotic and hydrostatic pressures.

What happens to ECF osmolality as Na+ concentration increases?

↑ ECF osmolality causes water to leave the cell.

What stimulates the thirst mechanism?

A rise in osmolality stimulates thirst.

Describe how water intake and output must relate to maintain balance.

Water intake must equal water output, approximately 2500 ml/day.

What are the sources of water intake?

Most water is taken in via ingested foods and beverages with some from metabolism.

What percentage of water output occurs through urine?

About 60% of water output occurs through urine.

What triggers ADH release during high osmolality?

A rise in osmolality stimulates ADH release.

What is the effect of drinking water on the thirst center?

Drinking water inhibits the thirst center.

What is the main driving force for water intake?

The thirst mechanism governed by the hypothalamic thirst center.

What does the hypothalamic osmoreceptors respond to?

Increased plasma osmolality of 1-2% and dry mouth.

What physical signals suppress the thirst sensation?

Relief of dry mouth and activation of stomach and intestinal stretch receptors.

What happens to urine volume when ADH decreases?

Decreased ADH leads to dilute urine and a drop in the volume of body fluids.

What factors can trigger ADH release besides osmolality changes?

Large changes in blood volume or pressure also trigger ADH release.

What is the consequence of hyperkalemia?

Hyperkalemia can lead to bradycardia, cardiac arrhythmias, and arrest.

What is the primary role of sodium in fluid and electrolyte balance?

Sodium is the most abundant cation in ECF, controlling fluid movements.

How does aldosterone affect sodium and potassium balance?

Aldosterone increases Na+ reabsorption and promotes K+ secretion.

What happens to the water volume in body fluids if Na+ content increases?

Increased Na+ content typically leads to an increase in water volume.

What do baroreceptors monitor in the cardiovascular system?

Baroreceptors monitor changes in blood volume and pressure.

What regulates blood levels of alkaline substances?

The kidneys regulate blood levels of alkaline substances.

How do hormones influence sodium balance in the body?

Hormones like aldosterone and ANP regulate sodium balance by controlling its reabsorption and excretion.

What is edema?

Edema is an atypical accumulation of interstitial fluid resulting in swelling.

What condition may occur due to hypotonic hydration?

Hypotonic hydration causes cellular overhydration or water intoxication.

What are the signs of dehydration?

Signs include 'cottony' oral mucosa, thirst, dry skin, and oliguria.

What happens in hyponatremia?

ECF osmolality decreases, leading to net osmosis of water into tissue cells, causing swelling.

What is the consequence of hypercalcemia on muscle and nerve activity?

Hypercalcemia inhibits neurons and muscle cells, potentially causing arrhythmias.

What role do chemical buffer systems have in pH regulation?

They resist pH changes when strong acids or bases are added.

What are the three major buffering systems?

Bicarbonate buffer system, phosphate buffer system, and protein buffer system.

What is the effect of respiratory acidosis on blood pH?

Respiratory acidosis causes blood pH to drop.

What condition indicates the inability of the respiratory system to eliminate CO2 effectively?

Respiratory acidosis.

What is the significance of PCO2 levels in acid-base balance?

PCO2 levels are the most important indicator of respiratory function in acid-base balance.

What conditions can result in metabolic acidosis?

Diabetic ketoacidosis, prolonged diarrhea, and alcohol ingestion can lead to metabolic acidosis.

How do kidneys participate in pH balance?

Kidneys excrete nonvolatile acids and regulate bicarbonate levels.

What occurs in metabolic alkalosis?

Metabolic alkalosis is indicated by an increase in blood pH and bicarbonate levels.

What physiological changes occur during respiratory compensation for metabolic acidosis?

The respiratory system increases the rate and depth of breathing.

What does hyperventilation lead to?

Hyperventilation can cause respiratory alkalosis due to decreased CO2 in the blood.

What is the role of aldosterone in potassium regulation?

Aldosterone stimulates the secretion of potassium into urine.

What is the typical blood pH range for arterial blood?

The normal arterial blood pH range is about 7.35 to 7.45.

What happens to calcium levels when parathyroid hormone (PTH) is released?

PTH increases calcium levels in the blood by promoting its release from bones.

Which electrolyte imbalance can lead to neuromuscular excitability and tetany?

Hypocalcemia can increase neuromuscular excitability, leading to tetany.

What buffer system is primarily responsible for maintaining ECF pH?

The bicarbonate buffer system is the main buffer in ECF.

What are the consequences of acid-base imbalances on the nervous system?

Severe imbalances can lead to CNS depression or overexcitation, potentially resulting in convulsions.

What is the consequence of high blood concentrations of HCO3-?

Elevated HCO3- indicates metabolic alkalosis.

What must the kidneys do to reabsorb bicarbonate?

To reabsorb bicarbonate, kidneys must secrete H+ ions.

What is the typical serum value for hypernatremia?

Hypernatremia is indicated by serum sodium levels greater than 145 mEq/L.

What mechanism prevents excessive sodium excretion?

Aldosterone promotes sodium reabsorption back into the bloodstream.

What effects does ANP induce on blood pressure?

ANP decreases blood pressure by inhibiting aldosterone and promoting sodium excretion.

What are the possible consequences of excessive aldosterone production?

Excessive aldosterone can lead to increased Na+ reabsorption, hypertension, and hypokalemia.

What are the signs of hypokalemia?

Signs of hypokalemia include muscle weakness and cardiac arrhythmias.

What is the effect of chemical buffers during exercise?

Chemical buffers help maintain blood pH during the elevated lactic acid production from exercise.

How does plasma protein contribute to pH balance?

Plasma proteins can bind to H+ ions, helping to stabilize pH.

What mechanism corrects metabolic acidosis?

The respiratory system increases ventilation to expel CO2 and reduce acidity.

What is considered normal ECF osmolality?

Normal ECF osmolality is about 280-300 mOsm.

What happens to muscle excitability at low potassium levels?

Low potassium levels can lead to hyperpolarization and decreased excitability of muscle cells.

What physiological buffer system operates during a prolonged period without respiration?

The renal system gradually compensates for acid-base imbalances during prolonged absence of respiration.

Where is the primary site for potassium regulation in the kidneys?

Potassium balance is primarily regulated in the distal convoluted tubule (DCT) and collecting duct.

What occurs to fluid shifts when Na+ levels change?

Changes in Na+ levels can prompt shifts in water retention or excretion and affect blood volume.

Explain the effect of hypotonic hydration on cells.

Hypotonic hydration causes cells to swell as ECF osmolality decreases, leading to water moving into the cells.

What are symptoms of metabolic alkalosis?

Metabolic alkalosis may result in confusion, muscle twitching, and irritability.

How does the body respond to low blood pressure?

The body triggers the renin-angiotensin-aldosterone system to retain water and sodium.

What condition may arise from dehydration and prolonged loss of fluids?

Dehydration can lead to weight loss, hypotension, and potentially hypovolemic shock.

What are the consequences of hyperphosphatemia?

Hyperphosphatemia can lead to reciprocal changes in calcium levels and metabolic disorders.

Describe how edema affects tissue function.

Edema increases the distance for nutrient diffusion and oxygen transfer, impairing tissue function.

What is the relationship between sodium concentration and blood pressure?

Sodium concentration affects blood volume, which in turn influences blood pressure.

What physiological role do stretch receptors play in thirst regulation?

Stretch receptors in the stomach provide feedback to inhibit thirst when the stomach is full.

What are the main contributions of ECF to sodium levels?

Sodium salts in the ECF contribute significantly to its overall osmotic concentration.

What symptom characterizes hypernatremia?

Common symptoms include confusion, lethargy, and possible coma.

What is a common cause of hyponatremia?

Hyponatremia may result from excessive water intake diluting sodium levels.

What factors can cause respiratory acidosis?

Respiratory acidosis can arise from conditions like pneumonia and chronic obstructive pulmonary disease.

How is metabolic acidosis corrected?

Compensated by increasing the rate and depth of respiration to expel CO2.

What effect does aldosterone have on urine output?

Aldosterone decreases urine output by promoting sodium and water reabsorption.

What pH indicates acidosis in the body?

A pH of less than 7.35 indicates acidosis.

What bodily mechanism compensates for respiratory acidosis?

The kidneys will compensate by reabsorbing bicarbonate and excreting H+.

How do dietary changes affect sodium balance?

Increased dietary sodium can elevate blood pressure as kidneys retain more fluid.

What happens in the body during hyperkalemia?

Hyperkalemia can lead to potentially fatal heart arrhythmias and neuromuscular issues.

What buffers are present in intracellular fluid?

Intracellular proteins and phosphates serve as buffers in ICF.

What process raises bicarbonate levels in the blood?

Metabolism generates H+, requiring the kidneys to produce more HCO3-.

What classifies disorders of electrolyte balance?

Disorders of electrolyte balance can be classified based on the anion or cation involved.

What is the importance of maintaining fluid balance?

Fluid balance is crucial for proper circulation, temperature regulation, and cellular function.