Regulation of Bicarbonate/Carbonic Acid Buffer System

What is the main goal of the regulation of the bicarbonate/carbonic acid system?

Which organ is responsible for regulating the metabolic component (HCO-3) in the bicarbonate/carbonic acid system?

What is the duration of respiratory compensation?

What is the effect of H2CO3 reduction on kidney function?

What is the term for a decrease in HCO-3 levels in the blood?

How many types of acid-base disturbances are there?

What is the primary function of buffer systems in the body?

What is the measure of the concentration of hydrogen ions in an aqueous solution?

How many moles of H+ are yielded by reactions in the body per day?

What is the term for the state of internal balance to maintain physical and chemical conditions by living systems?

What is the term for a molecule or ion capable of donating a proton (H+)?

What is the primary role of the kidney in regulating acid-base balance?

What is the term for a disturbance in which the body has too much acid?

What is the term for a disturbance in which the body has too much base?

What is the ratio of HCO3- to H2CO3 in normal arterial blood?

How do the kidneys respond to a decrease in HCO3- levels in the blood?

What is the pH of the renal tubular fluid when the Na+ – H+ exchange system stops?

What is the main mechanism by which the lungs regulate H2CO3 levels?

What happens to H2CO3 levels in the blood during hyperventilation?

What is the role of the kidneys in regulating the metabolic component of the acid-base balance?

What is the effect of an increase in H+ concentration on the respiratory center?

What is the pK of the buffer at 37°C?

Respiratory compensation is fast and reaches maximal capacity in 24 hours
Changes in ventilation affect the denominator (respiratory) component of the H-H equation

The ultimate aim of regulation is to maintain a ratio of 20 Bicarbonate : 1 Carbonic Acid
At this ratio, arterial blood pH = 7.40 ± 0.05
Kidneys regulate the metabolic component (HCO-3)
Lungs regulate the respiratory component (H2CO3)
Regulation also includes compensation for excess or deficiency of the other

There are four types of acid-base disturbances:
- Metabolic acidosis
- Metabolic alkalosis
- Respiratory acidosis
- Respiratory alkalosis

Happens due to:
- Build-up of acid in blood
- Excess HCO3- loss by excretion via kidney or diarrhea
Results in:
- Low HCO3- in blood
- Disruption of HCO3-/ H2CO3 ratio
The body tries to maintain the HCO3-/ H2CO3 ratio of 20:1 to keep the pH 7.40

Kidneys regulate the metabolic (HCO3-) component
Depending on the acid-base status, kidneys may:
- Excrete HCO3- in urine
- Reabsorb HCO3- partially or completely
- Synthesize HCO3- by renal tubules
Changes introduced by the kidneys affect the numerator of the H-H equation
HCO3- synthesis, excretion, or reabsorption involves the Na - H+ exchange mechanism by the kidney tubules

Lungs regulate the respiratory (H2CO3) component
Regulation is mainly by ventilation, i.e., Hypoventilation or Hyperventilation
In hypoventilation:
- CO2 is retained
- pCO2 in alveolar spaces ↑
- H2CO3 in the blood ↑
In hyperventilation:
- CO2 is exhaled "blown off"
- pCO2 in alveolar space ↓
- H2CO3 in the blood ↓

Homeostasis is the state of internal balance to maintain physical and chemical conditions by living systems
Acid is a molecule or ion capable of donating a proton (H+)
Base is a substance that dissociates in aqueous solution to form hydroxide ions OH−
Buffers are substances that maintain a constant pH by neutralizing the effects of hydrogen ions
pH is a measure of how acidic/basic water is or a measure of the concentration of hydrogen ions in an aqueous solution
pK is the pH value at which a chemical species will accept or donate a proton