Cellular Environment Alterations 2023.pdf

Online lecture for HLSC2460U Pathophysiology I Cellular Environment Alterations https://phys.org/news/2016-04-ion-impacts-million-molecules.html Selected topics from Chapter 3 (McCance &...

Online lecture for HLSC2460U Pathophysiology I Cellular Environment Alterations https://phys.org/news/2016-04-ion-impacts-million-molecules.html Selected topics from Chapter 3 (McCance & Huether 8th edition) by Syed Qadri 1 Topics to be covered Edema (to be reviewed in class) Alterations in Na+, Cl- & H20 balance (Tonicity) Alterations in K+ & Ca2+ balance Acid-Base imbalances 2 Alterations in Sodium, Chloride and Water Balance Water imbalances caused by changes in osmotic gradients sensitive to NaCl concentration Changes in tonicity (effective osmolality) Osmolality ≠ Osmolarity Normal plasma osmolality 280 – 294 mOsm/kg 3 4  Water & Solute Imbalances Alterations Mechanism Common Examples Isotonic = Changes in H2O are Loss: Hemorrhage, accompanied by proportional Hypovolemic Shock changes in [NaCl] Excess: Kidney failure, excess Extracellular [NaCl] normal i.v. fluids No change in cell shape Hypotonic = Extracellular [NaCl] Hyponatremia; water decreased intoxication H2O moves to intracellular space and cells swell Hypertonic = Extracellular osmolality Hypernatremia elevated Water deficit H2O moves to extracellular Hyperglycemia space and cells shrink 5 Homeostatic Response to Hyponatremia 6 Homeostatic Response to Hypernatremia 7 Alterations in Potassium and Calcium Balance Hypokalemia or Hyperkalemia Hypocalcemia or Hypercalcemia 8  Effects of K and Ca ions on membrane excitability Threshold Potential Resting Potential Muscle weakness Muscle excitability Heart dysrhythmias Seizures 9  ECG changes Serum [K+] 5.0 mEq/L Renal failure, burns, massive injuries hemolysis, RBC transfusion Increased neuromuscular excitability Cardiac dysrhythmias 10  Common Causes ❖ Hyperparathyroidism ❖ Decrease in PTH production (e.g surgical) ❖ Bone metastases ❖ Nutritional deficiency of calcium ❖ Prolonged immobilization ❖ Inadequate intestinal absorption ❖ Vitamin D deficiency Clinical ❖ Asymptomatic or with non-specific symptoms ❖ Increase in neuromuscular excitability Manifestations ❖ Can get complicated with kidney stone ❖ Chvostek or Trousseau's sign formation ❖ Convulsions or tetany Hormonal Regulation in Response to Calcium Imbalance Hypercalcemia & Hypocalcemia 11 Acid-Base Imbalances = Changes in the concentration of acids or bases in the blood that are not neutralized by buffering systems Types: Acidosis or Alkalosis Cause (etiology): Respiratory or Metabolic 12 Important Terms Acidosis Systemic increase in [H+] or loss of base = Decreased pH Alkalosis Systemic decrease in [H+] or excess of base = Increased pH Respiratory acidosis or alkalosis Imbalance caused by respiratory disorders Metabolic acidosis or alkalosis Imbalance caused by metabolic disorders (mostly renal) 13  The carbonic acid-bicarbonate buffering system Hydrogen ions Carbon dioxide Carbonic + + Acid Bicarbonate Water H+ + HCO3- H2CO3 CO2 + H2O Removed Released Removed from to from blood blood blood by by by kidney kidney alveolar tubules tubules ventilation 14  Primary and Compensatory Acid-Base Changes 15  Common Causes of Acid-Base Imbalances (we will study them throughout Patho I & Patho II) Acidosis Alkalosis Respiratory Depression of the respiratory center Alveolar hyperventilation Airway obstruction (e.g. heart failure, high altitudes, Disorders of lung improper use of mechanical ventilators) Disorders of chest wall or respiratory muscles Metabolic Renal failure Prolonged vomiting Diabetic ketoacidosis Gastric suctioning Excessive bicarbonate intake 16 Done! http://apod.nasa.gov/apod/ap120822.html 17