Cellular Adaptation in Pathophysiology

Pathophysiology Overview

• Pathophysiology studies altered bodily functions due to disease.
• "Pathos" (suffering) and "physis" (form) are its Greek roots.
• Diseases emerge when cells, tissues, and organs fail to maintain homeostasis under stress.

Cellular Adaptation

• Cells and tissues adapt to shield themselves from damage due to adverse conditions.
• Adaptations can be either permanent or temporary.
• Atrophy involves a decrease in cell size due to losing subcellular components.
  • The number of cells stays constant.
  • It's an attempt to cope with unfavorable conditions or disuse.
• Hypertrophy is the increase in cell size through synthesis of additional subcellular components.
• Hyperplasia involves an increase in the number of cells within a tissue or organ.
• Dysplasia includes variations in cell size, shape, and organization.
  • It's often found in epithelial cells with atypical changes.
• Metaplasia is a reversible adaptation where one adult cell type is replaced by another.

Fluid and Electrolyte Balance

• Biochemical reactions require an aqueous environment in the body.
• Disruptions in fluid and electrolyte balance can instigate or worsen diseases.
• Imbalances arise from excessive fluid output or input.
  • Examples include profuse sweating, salt intake, or dehydration.
• Water deprivation for three or more days could be fatal.
• The degree of fluid imbalance impacting homeostasis depends on size, age, and underlying conditions.
  • A loss of 30% of total body fluid could compromise homeostasis in a healthy adult.
  • A loss of only 10-15% of total body fluid could compromise homeostasis in a small child.
• Fluid therapy is a crucial step in resuscitation.

Edema

• Edema is accumulation of fluid in interstitial spaces.
• Increased capillary hydrostatic pressure, perhaps from venous obstruction, can be a cause.
• Edema can occur with an increased vascular volume.
• Adrenocortical hormones, pregnancy, and environmental heat stress can induce edema too.
• Prolonged standing increases the effects of gravity resulting in edema too.
• Decreased colloid osmotic pressure in capillaries occurs via plasma protein loss.
• Lymphatic vessel obstruction from infection, disease, or removal can cause edema.
  • Peripheral edema in ankles and feet is common.
• Sacral edema often occurs in bedridden patients.
• Ascites refers to fluid accumulation in the peritoneal cavity, also deemed edema.

Clinical Manifestations and Assessment of Edema

• Edema can be localized or widespread.
• Pulmonary edema may occur in cardiac patients or those falling due to submersion.
• Narcotic overdoses or high altitude pulmonary edema (HAPE) are also causes.
• Pulmonary Edema assessment should include auscultation of breath sounds, assessment of sacral edema, and jugular venous distention (JVD).
• Diagnostic tools incorporate ECG and vital signs monitoring.
• Medical history, including current and past medications, is crucial.
• Treatment mirrors the patient's chief complaint and presenting problem.
• Interventions involve CPAP, supplemental oxygen, or positional therapy.
• Nitrates and diuretics often have a role in hospitals.

Isotonic Fluid Imbalances

• Isotonic fluid deficit: extracellular fluid loss disproportionate to sodium and water levels.
  • Common via vomiting, diarrhea, plasma or blood loss (burns, hemorrhage).
  • Loop diuretics, fever, reduced fluid intake, and excessive sweating also play a part.
  • Comorbidities with physical exertion can exacerbate fluid loss.
• Isotonic fluid excess means a proportionate increase in both sodium and water in extracellular fluid.
  • Causes: heart failure, liver cirrhosis, renal failure, steroids, or excess sodium intake.
• Dehydration leads to orthostatic hypotension and decreased urine output (oliguria).
• High sodium levels increase risk of delirium and coma.

Electrolyte Imbalances: Sodium (Na+)

• Sodium (Na+) is vital for fluid balance, total fluid volume, and blood pressure regulation.
• Sodium facilitates muscle contraction and nerve impulse transmission
• Normal sodium level: 136–142 mEq/L.
• Abnormalities: nausea, weakness, confusion, and seizures.
• Hypertonic fluid deficit: water loss occurs without proportionate sodium loss which can cause hypernatremia.
  • Sodium level exceeds 143 mEq/L.
• Hypotonic fluid deficit: sodium loss exceeds water loss - can cause hyponatremia.
  • Serum sodium level falls below 135 mEq/L.
  • Causes: heart failure, cirrhosis, renal failure.
  • Syndrome of inappropriate antidiuretic hormone (SIADH) can also cause this
• Normal fluid volume with hyponatremia can be caused by SIADH.
  • Symptoms: fatigue, loss of appetite, nausea, muscle cramps, weakness, abdominal discomfort, headaches, confusion, seizures.
• Medical findings depend on the sodium level, as well as, how the abnormality developed.
  • The more acute the sodium level change, the more intense the symptoms.

Electrolyte Imbalances: Potassium (K+)

• Potassium (K+) regulates acid-base balance, muscle control, enzyme reactions, and osmolarity.
• Normal potassium levels: 3.5–5 mEq/L.
• Hypokalemia is the lack of potassium.
  • Common through decreased intake/absorption, potassium shifting into cells, renal/external losses.
  • Symptoms: muscle weakness, fatigue, cramping, ascending paralysis.
  • Can be fixed with IV potassium and supplements.
• Hyperkalemia is elevated potassium level.
  • Common via decreased excretion (kidney failure/medications), potassium shifts from within cells, dietary intake.
  • Interferes with neuromuscular function causing fatigue, nausea, muscle weakness, altered sensations, ascending paralysis.
  • ECG reflects cardiac dysrhythmias.

Electrolyte Imbalances: Calcium (Ca2+)

• Calcium is essential for bone and teeth strength and stability.
• Calcium enters through the gastrointestinal tract.
• Calcium depends on the presence of vitamin D
• Calcium is stored in bone tissue and excreted by the kidney
• Normal Calcium level: 8.2–10.2.
• Hypocalcemia is caused by decreased intake or absorption (lack of vitamin D), increased loss (alcoholism, diuretics), endocrine disease, sepsis.
  • Symptoms: muscle spasms, cramping, seizures, altered sensations, dysrhythmias observed on ECG.
• Hypercalcemia comes from increased intake/absorption (excess antacid use), endocrine disorders (adrenal insufficiency), neoplasms.
  • Symptoms: fatigue, weakness, nausea, constipation, frequent urination (polyuria) occur.
  • Treatment addresses the underlying cause

Electrolyte Imbalances: Phosphate (PO43-)

• Phosphate is an intracellular ion.
• Phosphate levels are regulated by the same mechanisms as calcium.
• Normal level: 2.3–4.7.
• Hypophosphatemia is caused by a lack of absorption.
  • Excessive loss in those with hyperparathyroidism or alcoholism also result in this
  • It can occur after glucose or anabolic steroid administration.
  • Abnormal loss of nutrients followed by inadequate replenishment in patients with diabetic ketoacidosis or chronic alcoholism also cause it.
  • Symptoms: dysrhythmias, hypotension, muscle weakness, altered mental status, breakdown of muscle fibers, loss of appetite, tremors, seizures, coma, susceptibility to infection.
• Hyperphosphatemia can happen via excessive vitamin D or laxative/enema use
• Vitamin D and laxatives can cause this
  • Metabolic acidosis and decreased excretion into the urine can also happen with acromegaly
  • Symptoms: tremors, overactive reflexes, confusion, seizures, muscle weakness, hypotension, heart failure, prolonged QT interval.

Electrolyte Imbalances: Magnesium (Mg2+)

• Magnesium is in the top intracellular cations.
• Normal range: 1.3–2.1.
• Hypomagnesemia can occur from diminished absorption/intake (alcohol use, malabsorption, malnutrition), renal losses (diuretics, chronic kidney disease), GI loss (diarrhea, vomiting).
  • Symptoms: weakness, muscle cramps, CNS issues, tremors, insomnia, personality changes, hypertension/tachycardia, dysrhythmias, confusion.
• Hypermagnesemia occurs with kidney insufficiency and insufficient excretion.
  • Symptoms: muscle weakness, decreased reflexes, altered mentality, dysrhythmias, paralysis, cardiac arrest.