Chapter 6 Pathos

Q1: What are the main body fluid compartments?

• Intracellular fluid (ICF): Inside cells (≈ 2/3 of total body water).

• Extracellular fluid (ECF): Outside cells (includes interstitial, intravascular, and transcellular fluids).

  • Interstitial fluid: Between cells.

  • Intravascular fluid: In blood vessels (plasma).

  • Transcellular fluid: “Third space” — CSF, pleural, peritoneal; not normally available for circulation

Q2: What determines water movement between compartments?

• Osmosis: Water moves from high → low concentration.

• Osmolarity: Solute concentration.

• Tonicity: Osmotic pressure between two solutions.

  • Isotonic: Equal concentration → no shift.

  • Hypotonic: Water moves into cells → swelling.

  • Hypertonic: Water moves out of cells → shrinkage

Q3: What are the major fluid regulators in the body?

• ADH (Antidiuretic Hormone): Retains water → ↓ urine output.

• Aldosterone: Retains sodium (and water); excretes potassium.

• ANP (Atrial Natriuretic Peptide): Released from overstretched atria → ↑ urine output, ↓ sodium/water

Q4: What does tonicity mean for cells?

• Hypertonic serum: Water leaves cells → shrink (crenate).

• Hypotonic serum: Water enters cells → swell or rupture

Q5: How are fluid levels monitored clinically?

• Daily weight: 1 kg = 1 L of fluid.

• I&O: Intake > Output = fluid retention.

• Labs: Hct, osmolality, electrolytes

Q6: What causes fluid excess?

• Intake/retention: Excess Na⁺ or water (high-sodium diet, hypertonic fluids, renal failure, Cushing’s, SIADH).

• Inadequate elimination: Heart/liver/renal failure

Q7: What are the manifestations of fluid excess?

Weight gain, edema (peripheral/periorbital/anasarca), JVD, bounding pulse, crackles, hypertension, dyspnea

Q8: How is fluid excess treated?

Diuretics, sodium/fluid restriction, Fowler’s position, compression stockings

Q9: What causes dehydration?

Poor intake, excessive loss (GI, diuretics, sweating, burns, hemorrhage, diabetes insipidus, 3rd spacing)

Q10: What are the signs of dehydration?

Thirst, dry mucous membranes, poor skin turgor, hypotension, tachycardia, weak pulse, oliguria, weight loss, flat neck veins

Q11: How is dehydration treated?

Identify cause and replace fluids orally or IV (isotonic or hypotonic based on need)

Q12: What are electrolytes and their charges?

• Cations (positive): Na⁺, K⁺, Ca²⁺, Mg²⁺

• Anions (negative): Cl⁻, HCO₃⁻, PO₄³⁻
  They regulate muscle/nerve activity, acid-base balance, and hydration

Q13: Normal range and function?

• 135–145 mEq/L

• Controls osmolarity, nerve/muscle impulses, acid-base balance

Q14: Causes and signs of hypernatremia?

• Causes: Excess Na⁺ or water loss (Cushing’s, hypertonic IVs, dehydration).

S/S: Thirst, dry mucosa, flushed skin, weakness, confusion, seizures

• Treatment: Hypotonic fluids, water replacement.

Q15: Causes and signs of hyponatremia?

• Causes: Diuretics, vomiting, excess water, renal/heart failure.

• S/S: Headache, confusion, seizures, edema, poor skin turgor

• Treatment: Limit fluids, give sodium

Q16: Normal range and function?

• 3.5–5 mEq/L

• Major intracellular cation; essential for electrical conduction, muscle contraction, and acid-base regulation

Q17: What causes hyperkalemia and what are its effects?

• Causes: Renal failure, acidosis, tissue damage, K⁺ supplements.

• S/S: Muscle weakness, paresthesia, bradycardia, arrhythmias, cardiac arrest

• Treatment: Calcium gluconate, insulin + glucose, diuretics, dialysis.

Q18: What causes hypokalemia and what are its effects?

• Causes: Vomiting, diuretics, steroids, alkalosis.

S/S: Weakness, cramps, hypotension, irregular pulse, constipation, cardiac arrest

• Treatment: Oral/IV K⁺ replacement.

Q19: Normal range and function?

• 8.6–10.5 mg/dL (4–5 mEq/L)

• Bone/teeth health, nerve transmission, muscle contraction, clotting.

• Regulated by PTH (raises Ca²⁺) and calcitonin (lowers Ca²⁺)

Q20: What are causes/symptoms of hypercalcemia?

• Causes: Cancer, immobility, thiazide diuretics, hyperparathyroidism.

• S/S: Lethargy, confusion, weakness, constipation, kidney stones, arrhythmias

  Treatment: IV fluids, diuretics, calcitonin, mobility.

Q21: What are causes/symptoms of hypocalcemia?

• Causes: Hypoparathyroidism, renal failure, Vit D deficiency, diarrhea.

• S/S: Muscle spasms, tetany, paresthesia, positive Trousseau’s & Chvostek’s signs

• Treatment: Calcium and Vit D replacement, treat phosphorus excess.

Q22: Normal range and function of magnesium?

• 1.8–2.5 mEq/L

• Maintains nerve/muscle function, cardiac rhythm, and metabolism

Q23: Hypermagnesemia vs. Hypomagnesemia — causes and S/S?

Type	Causes	Symptoms	Treatment
Hypermagnesemia (>2.5)	Renal failure, antacid use	Lethargy, decreased reflexes	Diuretics, dialysis, IV calcium
Hypomagnesemia (<1.8)	Malnutrition, alcoholism, diarrhea	Tremors, tetany, confusion	Mg replacement (oral/IV)

Q24: What is the normal blood pH and ABG values?

• pH: 7.35–7.45

• PaCO₂: 35–45 mmHg

• HCO₃⁻: 22–26 mEq/L

• PaO₂: 75–100 mmHg

• SaO₂: 95–100%

Q25: What are the main systems that regulate acid–base balance?

• Buffer systems (immediate):

  • Bicarbonate–carbonic acid system (primary ECF buffer).

  • Protein, phosphate, and hemoglobin systems.

• Respiratory system: Excretes CO₂ (acid).

• Renal system: Excretes H⁺ and retains HCO₃⁻ (base)

Q26: How does potassium affect pH?

In acidosis, H⁺ moves into cells → K⁺ moves out → hyperkalemia.
In alkalosis, H⁺ moves out → K⁺ moves in → hypokalemia

Imbalances chart

Type	pH	Main Problem	Example Causes
Metabolic Acidosis	↓ pH, ↓ HCO₃⁻	Acid excess or base loss	DKA, lactic acidosis, diarrhea, renal failure
Metabolic Alkalosis	↑ pH, ↑ HCO₃⁻	Acid loss or base excess	Vomiting, diuretics, antacids
Respiratory Acidosis	↓ pH, ↑ CO₂	CO₂ retention	COPD, hypoventilation, drug overdose
Respiratory Alkalosis	↑ pH, ↓ CO₂	CO₂ loss	Anxiety, hyperventilation, fever.

Q27: What is the anion gap and its significance?

• Formula: Na⁺ – (Cl⁻ + HCO₃⁻)

• Normal: 6–9 mEq/L.

• ↑ Gap: Indicates metabolic acidosis (lactic or ketoacidosis)

Q28: What are signs of acidosis vs. alkalosis?

• Acidosis: Weakness, confusion, dysrhythmias, Kussmaul’s respirations (deep, rapid).

• Alkalosis: Irritability, paresthesia, muscle cramps, tetany, seizures

Q29: How do you determine if the imbalance is respiratory or metabolic?

• HCO₃⁻ abnormal → metabolic

• PaCO₂ abnormal → respiratory

• pH shows direction (acidic <7.35, basic >7.45

Q30: What does “compensation” mean in acid-base balance?

The body adjusts other systems to restore pH.

• Metabolic issue → lungs compensate by changing CO₂.

• Respiratory issue → kidneys compensate by adjusting HCO₃⁻

Q31: How are ABGs interpreted step-by-step?

• Check pH (acidic/basic).

• Check PaCO₂ (acidic if ↑, basic if ↓).

• Check HCO₃⁻ (acidic if ↓, basic if ↑).

• Match pH with CO₂ or HCO₃⁻ to identify cause.

• Determine if compensation is present