Acid-base Balance Flashcards
PH
• pH = measure of H* concentration
• Scale 0-14
• Below 7 = acidic
• Above 7 = basic
• 7 = neutral
Acid-Base Balance
• Production of hydrogen ions = loss of hydrogen ions
• Acidosis; results from a pH below 7.35
• Alkalosis: results from a pH above 7.45
Fixed acids
• Can only be eliminated by kidneys
• Generated through catabolism of amino acids, phospholipids and nucleic acids
Metabolic acids
• By-products of cellular metabolism (pyruvate, lactic acid, ketone bodies synthesized from acetvl-CoA)
• Metabolized quickly, do not accumulate
Volatile acids
Are exhaled
When amount of CO2 goes up
-combines with water> more H+> pH drops (acidic)
When CO2 goes down
Less H2CO3> less H+ ions> higher pH (basic)
Buffer systems
• Stabilize pH by adding or removing H+ from solution
• Neutralize acids as they travel through body
• Protein buffer systems
• Phosphate buffer system
• Carbonic acid - bicarbonate buffer system
Phosphate buffer system
Has an important role in buffering pH of the ICF and of urine
Protein buffer systems
•contribute to the regulation of pH in the ECF and IFC. These buffer systems interact extensively with the other two buffer systems
•hemoglobin buffer system (RBCS only)
•amino acid buffers (all proteins)
•plasma protein buffers
carbonic acid-bicarbonate buffer system
Is most important in the ECF
Carbonic acid - bicarbonate buffer system
• Prevents changes in the pH of the ECF due to organic or fixed acids
•need more bicarbonate then use the bicarbonate reserve
Carbonic acid - bicarbonate buffer system limitations
• Can’t protect against changes in pH due to CO, levels
• Can only function when respiratory system is working properly
Maintaining acid-base balance
• Buffer systems are a temporary solution
• Respiratory compensation: increase or decrease respiratory rate and depth
• Renal compensation: alter rates of H+ & HCO-reabsorption & secretion
Response to acidosis
Starts with an increase in H+> increase in H2CO3 (carbonic acid)> increase in CO2
Response to alkalosis
Remove H+> decease carbonic acid and CO2
-can slow breathing to fix this
Respiratory acidosis
• Respiratory system can’t eliminate all of the CO2
•usually caused by hypoventilation (not breathing enough)
• Acute
• Immediate, life-threatening (drowning)
• Chronic (COPD)
• Compensatory mechanisms still functioning
• Due to injuries/damage to CNS and/or damage to respiratory system
• Respiratory alkalosis
•Respiratory system lowers CO2 to below-normal levels (hypocapnia)
• Temporarily caused by hyperventilation
• relatively uncommon
Metabolic Acidosis
• Production of fixed or metabolic acids
• Lactic acidosis
• Ketoacidosis
• Kidney damage (inability to excrete H+ like in diabetes)
• loss of bicarbonate (diarrhea)
Metabolic Alkalosis
• HCOz becomes elevated
• Alkaline tide (bicarbonate levels in blood increase when HCI is produced in stomach)
• Repeated vomiting
• Uncommon
