Physiology pH Balance

• Blood pH level range necessary for life is 6.8-7.8
• Normal blood pH is 7.4-7.42 = 40 nmol/L - 42 nmol/L
• Acidemia/acidosis: pH< 7.35
• Low pH levels = lower neurons and CNS activity
• Acidemia/ acidosis can result in a coma & lack of respiratory stimulus
• Alkalemia/alkalosis: pH >7.45
• High pH levels = increased neuron activity
• Alkalemia/alkalosis can cause potential muscle tetanus & inactivity of respiratory muscle cycles
• pH buffers (usually acid buffers) help to maintain blood pH
• Acid buffers reversibly bind H+
• Base buffer reversibly binds OH-
• Bicarbonate has a free HCO3 that can buffer nonvolatile acids (lactic acids, etc.)
• Gaining H+ can lower pH levels
• Most H+ is bound to Hb
• Hypoventilation: respiratory disease (asthma & COPD)
• Metabolic production of nonvolatile acids from proteins, causes lower pH
• Types of nonvolatile acids: phosphoric acids, sulfuric acids, lactic acids
• Ingestion of acids can cause low pH levels
• Loss of HCO3 can lower pH levels (through urine or diarrhea)
• Secreting H+ can fix low pH
• Exhaling CO2 can increase pH
• The renal H+/K+ antiport can cause secretion of H+ and increase reabsorption of K+
• The renal antiport can potentially cause hyperkalemia
• Ingestion of buffers can increase pH
• Reabsorb & making new HCO3- can increase pH (urine)
• Loss of H+ can cause an increase in pH
• Metabolism of organic ions can cause loss of H+
• Urine can cause loss of H+
• Gaining HCO3- causes a loss in pH (vomitting)
• Keeping H+ can lower pH (hypoventilation)
• H+/K+ antiport: reabsorbs H+ and increase secretion of K+ (potential kypokalemia
• Filter and secrete HCO3- lowers pH (urine)
• 1. Respiratory compensation: for non-respiratory changes in pH (metabolic only)
• Compensation of acid-base balance- manipulate excretion & retention of H+ via CO2
• 2. Renal compensation: major menas of compensation for changes in pH+ (metabolic or respiratory)
• Compensation of acid-base balance- Manipulate renal excretion & reabsorption of H+ & HCO3-
• Respiratory center response to metabolic acidemia/acidosis- increase H+ to increase stimulation of peripheral chemoreceptors & inspiratory neurons
• respiratory center response to metabolic alkalemia/alkalosis- decrease H+ to decrease stimulation of peripheral chemoreceptors & inspiratory neurons
• Renal compensation: for respiratory & metabolic changes in H+
• H+ secretion= H+ filtered + H+ secreted - H+ reabsorbed