Acid Base Balance (MOD EXAM-1)

Describe acids in the blood and the types there are in the body

• Molecules that release H+ into the blood

• Hydrochloric acid:

• •HCl → H⁺ + Cl^-

  •HCL really want to move to the right (strong)

• Carbonic Acid

  • •H₂CO₃  →  H⁺ + HCO₃^–

Strong acids dissociate_______ than weak acids

easier

Describe bases in the blood

• Molecules that can accept H+ or increase OH- when in water

• Bicarbonate

  • •HCO₃^– + H⁺ →  H₂CO₃      

Strong bases react _____ and _____ to neutralize H+

rapidly and strongly

Describe buffers in the blood

• Substances that reversibly bind to H+ to keep the body's pH in balance and prevent the body from becoming too acidic or alkalotic.

• Carbonic acid is the most important buffer

Identify the normal range for pH

arterial blood pH is 7.35 to 7.45

Describe the respiratory response to altered pH

• The lungs control the "acid" by regulating carbon dioxide.

• If arterial pCO2 increases, the alveoli work harder to excrete more CO2.

• Hyperventilation →gets rid of CO2→ (decreasing arterial pCO2)→ causing a respiratory alkalosis

• Hypoventilation→ holds onto CO2 (increasing arterial pCO2)→ causing a respiratory acidosis

Describe the renal response to altered pH

• The kidneys control the "base" by regulating bicarbonate.

• Their two main jobs are to get rid of hydrogen ions through the urine and to regenerate bicarbonate from the urine to account for acid production

• Carbonic anhydrase enzyme drives acid-base balance and bicarbonate reabsorption

Discuss the relationship of potassium in response to acid base disturbances.

• 98% of the body's potassium is intracellular (inside the cell).

• In acidemia (too much H+), the cell exchanges its intracellular K+ for the extracellular H+ to compensate. This causes increased K+ in the blood (hyperkalemia), which can lead to fatal arrhythmias.

• In alkalemia (too little H+), the cell exchanges intracellular H+ for extracellular K+, leading to decreased K+ in the blood (hypokalemia).

What does acidemia lead to with regards to potassium?

HYPERkalemia

What does alkalemia lead to with regards to potassium?

HYPOkalemia

Describe the difference between (1) acidosis and (2) acidemia

1. An excess of acid in the body fluids

2. Specifically refers to arterial blood pH dropping below 7.35 (think of numbers)

Describe the difference between (1)alkalosis and (2) alkalemia

1. An excess of base in the body fluids

2. Specifically refers to arterial blood pH rising above 7.45 (think of numbers)

State which values in a normal arterial blood gas are actually measured, and which is/are calculated from the others.

MEASURED: pH, pCO2, pO2

CALCULATED: HCO3- (Bicarbonate), Base Excess / Deficit, SO2 (Oxygen Saturation)

Demonstrate the ability to interpret a set of ABG values (pH, pCO2 and HCO3) and indicate which type is present. (respiratory acidemia/alkalemia or metabolic acidemia/alkalemia)

• Interpret these values using the ROME rule

• Respiratory is Opposite: If pH goes up and PCO2 goes down, it is Respiratory alkalosis. If pH goes down and PCO2 goes up, it is Respiratory acidosis.

• Metabolic is Equal: If pH goes up and HCO3 goes up, it is Metabolic alkalosis. If pH goes down and HCO3 goes down, it is Metabolic acidosis.

If pH goes up and PCO2 goes down, it is…

Respiratory alkalosis

If pH goes down and PCO2 goes up, it is..

Respiratory acidosis

If pH goes up and HCO3 goes up, it is..

Metabolic alkalosis

If pH goes down and HCO3 goes down, it is…

Metabolic acidosis

Describe what it means to have a simple disturbance

• The disturbance is limited to just the primary disorder and the body's expected secondary (adaptive) response

Describe what it means to have a mixed acid-base disturbance

• There are at least 2 separate primary acid-base abnormalities occurring at the exact same time. A mixed disturbance is suspected when the body's adaptive response is not what you would expect it to be

• Need to look at the hx and PE in these pts to understand the process occuring