Acid-Base Imbalances – Vocabulary Flashcards

Page 1: Acid-Base Imbalances Overview

• Topic: Metabolic Acidosis & Alkalosis, Respiratory Acidosis & Alkalosis
• Context: Course material for NURS 3110; focus on regulation, imbalance types, compensation, and clinical questions.

Page 2: Announcements

• Regulation of Acid-Base Balance – reminders and updates
• Check-in: Dr. Perez on iClicker subscription
• Optional Review Session: tomorrow 11:30–12:45 in Room 320 and by Zoom (link in Canvas)
• Kahoot! Session: Sundays at 7 PM by Zoom with Aubrey and Isaac
• Exam Platforms: Examplify/ExamSoft for exam administration
• For pre-nursing students: look for an email from Josh Ballinger-Walker; if not received, email today confirming you looked but did not receive it
• Exam 1: Tuesday, close to NCLEX conditions
  • Prepare by placing phones, watches, bottles, etc., in a bag against a wall
  • Only a pencil/pen and your device with Examplify downloaded
  • Scratch paper provided; write your name on it and return when you show your green screen to receive credit
• TRIO – STEM–H speaker

Page 3: Acid-Base Measurement

• Topic heading only (intro to measurement concepts)

Page 4: pH Scale

• The pH scale expresses the concentration of hydrogen ions [H+] in a solution
• Normal blood pH: 7.35–7.45 (slightly alkaline)
• Stomach contents: pH ~1–2 (very acidic)
• Memory cues:
  • Lower pH means more acidic: “Drop acid”
  • The pH 1–14 scale can be remembered as A…B with 1…14 (simplified mnemonic)
• Alkaline substances have higher pH values

Page 5: Exponents and the pH Scale

• Relationships between numbers and their powers of 10:
  • 0.1 = 10^{-1}
  • 1 = 10^{0}
  • 10 = 10^{1}
  • 100 = 10^{2}
  • 1000 = 10^{3}
• Exponent notation for small/large numbers on the pH scale:
  • 0.00000000000001 = 10^{-14}
  • 0.0000001 = 10^{-7}
  • 0.01 = 10^{-2}
  • 0.1 = 10^{-1}
• Note: Five pH values represent the concentration exponent without the minus sign (as illustrated in the slide visuals)

Page 6: Regulation of Acid-Base Balance

• Section heading for broader regulation concepts

Page 7: Buffer Systems

• A buffer is any molecule that will accept a hydrogen ion (H+) and increase the pH of the fluid
• Primary buffers discussed:
  • Bicarbonate ion (HCO3-): primarily in plasma and urine filtrate
  • Phosphate (PO4^{3-}): primarily in cytoplasm and urine filtrate

Page 8: Acid Removal Systems (General Concept)

• Acid removal systems can eliminate acids and/or retain bases (alkaline molecules)
• Lungs: regulate CO2
  • CO2, when dissolved in water, is converted to carbonic acid (a relatively weak acid):
  • ext{CO}2 + ext{H}2 ext{O}
    ightleftharpoons ext{H}2 ext{CO}3
    ightleftharpoons ext{H}^+ + ext{HCO}_3^-
  • The same equation works in reverse depending on circumstances

Page 9: Lung Regulation of Acid-Base Balance

• Low plasma pH stimulates an increase in respiratory rate (and the reverse when pH is higher)
• Mechanism: increased respiratory rate leads to more CO2 removal (Blow off CO2)
• CO2 + H2O ⇌ H2CO3 ⇌ H+ + HCO3-

Page 10: Kidney (Renal) Acid Removal Systems

• Renal tubules regulate acid-base balance by:
  • Secreting/excreting H+ into urine filtrate
  • Retaining/regenerating bicarbonate ion (HCO3-)

Page 11: Test Your Knowledge – Q1

• Question: What happens to the pH of the blood when the kidneys retain H+?
  • Options: pH decreases; pH increases
  • Answer: Retaining H+ makes the blood more acidic; pH decreases
  • Focus: Kidney H+ retention lowers blood pH; bicarbonate is not retained in this case

Page 12: Test Your Knowledge – Q2

• Question: What happens to the pH of the blood when the lungs blow off CO2?
  • Options: pH decreases or increases
  • Answer: pH increases (blood becomes less acidic) as CO2 is exhaled; reaction shifts away from carbonic acid
  • Note: CO2 + H2O ⇌ H2CO3 ⇌ H+ + HCO3-

Page 13: Concepts in Acid-Base Imbalance

• Section heading for key concepts

Page 14: Core Concepts (Recap)

• Normal arterial blood/plasma pH range: 7.35–7.45
• Definitions:
  • Acidosis: pH < 7.35
  • Alkalosis: pH > 7.45
• Causes are categorized as respiratory vs metabolic (non-respiratory)
• Distinction: Respiratory vs metabolic etiologies for acidosis and alkalosis

Page 15: Compensation for pH Alteration

• Renal compensation for respiratory acidosis or alkalosis
• Respiratory compensation for metabolic acidosis or alkalosis
• Correction vs. compensation:
  • Correction: the faulty system corrects itself (e.g., respiratory system correcting to restore pH)
  • Compensation: the other system compensates (e.g., metabolic system compensates for a respiratory problem)
• Mechanisms:
  • Kidneys can increase or decrease secretion/excretion of H+
  • Lungs can increase or decrease CO2 removal

Page 16: Types of Acid-Base Imbalances

• Overview heading

Page 17: Overview Table – Types and Causes

• Categories:
  • Metabolic Acidosis / Metabolic Alkalosis
  • Respiratory Acidosis / Respiratory Alkalosis
• Indicate primary problem (metabolic vs respiratory) and direction of pH shift

Page 18: Metabolic Acidosis – Common Causes

• Common causes:
  • Increase in non-carbonic (metabolic) acids
  • Renal (kidney) failure
  • Lactic acid overproduction
  • Ketone overproduction
  • Renal retention of H+

Page 19: Metabolic Acidosis – Pathophysiology & Compensation

• Pathophysiology:
  • Low pH due to accumulation of non-carbonic acids (lactic acid, ketones)
  • Renal response: excrete H+ and regenerate/reabsorb HCO3- (if kidneys are functional)
  • Increased CO2 removal indirectly reduces carbonic acid (H2CO3)
• Compensation:
  • Renal: increased H+ excretion and HCO3- regeneration/reabsorption
  • Respiratory compensation: low plasma pH stimulates respiratory centers to increase rate and depth of breathing (Kussmaul respirations in severe metabolic acidosis)
• Notes: “Kussmaul respirations” described as a deep, prolonged exhalation pattern

Page 20: Metabolic Alkalosis – Common Causes

• Common causes:
  • Loss of non-carbonic (metabolic) acids
  • Prolonged vomiting or gastric suctioning
  • Net loss of H+ with retention of bicarbonate

Page 21: Metabolic Alkalosis – Pathophysiology & Compensation

• Pathophysiology:
  • High pH due to H+ loss and/or bicarbonate retention
• Correction/Compensation:
  • Renal: retention of H+ with bicarbonate excretion
  • Increased CO2 retention (to increase carbonic acid) raises H2CO3 levels
• Compensation:
  • Respiratory: elevated plasma pH stimulates brain stem to decrease respiratory rate

Page 22: Test Your Knowledge – Q: Renal Failure and Acid-Base Imbalance

• Question: Which imbalance is caused by renal failure?
  • Options: Metabolic acidosis or metabolic alkalosis
  • Correct: Metabolic Acidosis (kidneys retain H+; pH lowers)

Page 23: Test Your Knowledge – Q: Renal Failure Compensation (Time permitting, breakout rooms)

• Question: How does the body compensate for metabolic acidosis caused by renal failure?
  • Options include: kidneys excrete HCO3-, kidneys excrete H+, lungs retain or blow off CO2
  • Correct interpretation: The lungs can blow off CO2 to increase pH; kidneys would normally excrete H+ and retain HCO3- but in renal failure this compensation may be impaired

Page 24: Respiratory Acidosis – Common Causes

• Primary issue: CO2 retention
• Decreased respiratory rate due to:
  • Brain stem trauma
  • Over-sedation or opioid overdose
  • Paralysis of respiratory muscles

Page 25: Respiratory Acidosis – Additional Causes

• Other causes: increase in carbonic acid due to CO2 retention; disorders of the chest wall impairing breathing (e.g., broken ribs, kyphoscoliosis, extreme obesity)

Page 26: Respiratory Acidosis – Additional Causes (continued)

• Decreased ventilation and/or gas exchange from pulmonary disease (e.g., pneumonia, emphysema, cystic fibrosis)
• Example listed: Pneumonia

Page 27: Respiratory Acidosis – Pathophysiology & Compensation

• Pathophysiology:
  • CO2 retention → increased carbonic acid → decreased plasma pH
• Correction: None – lungs alone cannot correct the acid-base imbalance rapidly
• Compensation: In chronic respiratory acidosis, renal compensation occurs (kidneys secrete/excrete H+ and regenerate/reabsorb HCO3-)

Page 28: Test Your Knowledge – Q: Respiratory Acidosis (Clinical Findings)

• Select all that apply:
  • Hypoventilation (true)
  • Hyperventilation (false)
  • Vomiting (false)
  • Low pH (true)
  • High pH (false)

Page 29: Test Your Knowledge – Q: Respiratory Acidosis – Teaching Point

• Which statement indicates need for further teaching?
  • Options include:
  • “This happens because my lungs are removing too much CO₂.” (Incorrect for acidosis; removing too much CO2 would cause alkalosis)
  • “My breathing may slow down or become shallow.” (True in some cases; may need clarification)
  • “Chronic bronchitis can lead to this condition.” (True association)
  • “I should use my incentive spirometer regularly to prevent this.” (Clinical practice relevant to prevention)
  • “This means my blood is more acidic due to high CO₂ levels.” (True)

Page 30: Respiratory Alkalosis – Common Causes

• Causes of increased CO2 removal (hyperventilation):
  • Hyperventilation due to hypoxemia (e.g., high altitude, acute respiratory conditions), fever, anemia
  • Improper use of mechanical ventilation (ventilator rate too high)
  • Hyperventilation associated with anxiety/panic attacks
• Hypoxemia tends to drive hyperventilation
• Consequence: increased respiration blows off CO2, reducing carbonic acid levels

Page 31: Respiratory Alkalosis – Pathophysiology & Compensation

• Pathophysiology:
  • Hyperventilation removes CO2 → decreased carbonic acid → increased pH
• Note: Renal compensation for respiratory alkalosis is unusual because causes are typically acute and reversible

Page 32: Test Your Understanding – Q: Ventilated patient with pH 7.49 and low CO2

• Likely diagnosis: Respiratory alkalosis (not metabolic alkalosis, which would not present with low CO2 and high pH in that context)

Page 33: Test Your Understanding – Q: Pneumonia patient with pH 7.30 and high CO2

• Likely diagnosis: Respiratory acidosis (high CO2 indicates carbonic acid accumulation)

Page 34: Test Your Understanding – Q: Compensation for Respiratory Acidosis

• How does the body compensate?
  • Correct answer: Kidneys retain HCO3- (bicarbonate) to buffer the excess H+; they also excrete H+ as needed
  • Other options (retaining H+, retaining CO2, etc.) are not the primary compensatory pathway for respiratory acidosis

Page 35: Exponents and the pH Scale (Closing)

• Review of exponent notation:
  • 1000 = 10^{3}
  • 100 = 10^{2}
  • 0.00000000000001 = 10^{-14}
  • 0.0000001 = 10^{-7}
  • 0.01 = 10^{-2}
  • 0.1 = 10^{-1}
• Final reminder: pH relates to hydrogen ion concentration; lower pH means higher [H+] and more acidity, higher pH means lower [H+] and more alkalinity

Key Equations and Concepts (summary)

• Buffer systems:
  • Buffers resist pH change by accepting H+; major buffers include ext{HCO}3^- in plasma/urine filtrate and ext{PO}4^{3-} in cytoplasm/urine filtrate
• Carbonic acid buffering in lungs:
  • ext{CO}2 + ext{H}2 ext{O}
    ightleftharpoons ext{H}2 ext{CO}3
    ightleftharpoons ext{H}^+ + ext{HCO}_3^-}
• For metabolic acidosis, compensation includes renal H+ excretion with bicarbonate regeneration and increased CO2 removal via faster respiration (Kussmaul respirations in severe cases)
• For metabolic alkalosis, compensation includes renal H+ retention with bicarbonate excretion and increased CO2 retention; respiratory compensation reduces ventilation to increase CO2 and carbonic acid
• For respiratory acidosis, compensation occurs mainly via kidneys (renal) to regenerate HCO3- and excrete H+ over time; for acute cases, compensation is limited
• For respiratory alkalosis, renal compensation (H+ retention, HCO3- excretion) is less common in acute settings; frequent teaching notes emphasize the acute, reversible nature of causes
• Normal arterial pH range: 7.35-7.45
• Acid-base disorders are categorized as metabolic or respiratory, and as acidosis or alkalosis based on the direction of pH change

Quick reference for exam-style prompts

• If pH is < 7.35 and CO2 is elevated: respiratory acidosis (if acute) or metabolic acidosis with respiratory compensation (context matters)
• If pH is > 7.45 and CO2 is low: respiratory alkalosis
• If pH is < 7.35 with low HCO3-: metabolic acidosis; check time course for compensation
• If kidneys are retaining H+ and bicarbonate is decreasing: metabolic acidosis with renal involvement
• If lungs are retaining CO2 and pH is low: respiratory acidosis with possible renal compensation in chronic stages