Acid Base Physiology | Part Two | Respiratory Regulation | Respiratory Physiology

Summary

This video explains how the lungs regulate acid-base balance in the body. It covers the role of the Henderson-Hasselbalch equation, which links pH to bicarbonate and carbon dioxide concentrations. The lungs manage blood pH by adjusting carbon dioxide levels through ventilation, in response to central and peripheral chemoreceptors. The video also explores how respiratory and metabolic acidosis and alkalosis affect pH and how the kidneys compensate for these imbalances. This comprehensive overview highlights the interconnectedness of the lungs, kidneys, and buffers in maintaining a stable blood pH of around 7.4.

Takeaways

• 😀 The body has three systems that regulate acid-base balance: buffers, lungs, and kidneys.
• 😀 pH is determined by the concentration of hydrogen ions, with low pH indicating acidosis and high pH indicating alkalosis.
• 😀 The Henderson-Hasselbalch equation describes the relationship between pH, bicarbonate, and CO2 levels: pH = pK + log([HCO3^-] / (0.03 * PCO2)).
• 😀 The lungs regulate blood pH by controlling CO2 levels through respiration. An increase in CO2 leads to acidosis (low pH), and a decrease leads to alkalosis (high pH).
• 😀 Central chemoreceptors in the brainstem and peripheral chemoreceptors in the carotid and aortic bodies help regulate ventilation based on CO2 and pH levels.
• 😀 Increased metabolism results in more CO2 production, which lowers pH (acidosis). Increased ventilation helps expel CO2 and raise pH (alkalosis).
• 😀 The blood-brain barrier allows CO2 to cross, which then combines with water to form carbonic acid and release hydrogen ions, stimulating increased ventilation to normalize pH.
• 😀 The kidneys compensate for acid-base imbalances by increasing or decreasing bicarbonate reabsorption and hydrogen ion excretion.
• 😀 There are four primary types of acid-base disturbances: respiratory acidosis, respiratory alkalosis, metabolic acidosis, and metabolic alkalosis.
• 😀 In respiratory acidosis (hypoventilation), CO2 retention causes a drop in pH, and the kidneys compensate by increasing bicarbonate production.
• 😀 In metabolic acidosis, low pH stimulates peripheral chemoreceptors to increase ventilation, helping to remove CO2 and raise pH.

Q & A

What are the three regulatory systems of acid-base balance in the body?

The three regulatory systems of acid-base balance are buffers, the lungs, and the kidneys.

What is the significance of the Henderson-Hasselbalch equation in acid-base balance?

The Henderson-Hasselbalch equation helps determine the pH of a solution, which is essential for understanding how acid-base balance is maintained in the body.

How do the lungs regulate acid-base balance?

The lungs regulate acid-base balance by controlling the levels of carbon dioxide in the blood, which influences the pH according to the Henderson-Hasselbalch equation.

What is the normal pH of blood, and what happens during acidosis and alkalosis?

The normal pH of blood is around 7.4. During acidosis, the pH drops due to increased hydrogen ion concentration, while during alkalosis, the pH rises due to a decrease in hydrogen ions.

What role do chemoreceptors play in the regulation of acid-base balance?

Chemoreceptors in the brainstem (central chemoreceptors) and carotid and aortic bodies (peripheral chemoreceptors) monitor changes in hydrogen ion concentration and oxygen levels to adjust ventilation and maintain pH balance.

How does an increase in cellular metabolism affect acid-base balance?

An increase in cellular metabolism leads to more carbon dioxide production, which lowers pH and can cause acidosis if not properly regulated by the lungs and kidneys.

What happens when carbon dioxide crosses the blood-brain barrier?

When carbon dioxide crosses the blood-brain barrier, it forms carbonic acid, which dissociates into hydrogen ions, triggering the inspiratory center in the brainstem to increase ventilation and remove excess CO2, normalizing pH.

How do kidneys compensate for respiratory acidosis?

In respiratory acidosis, the kidneys compensate by increasing bicarbonate reabsorption and secreting more hydrogen ions, which raises the pH toward normal.

What is the difference between respiratory and metabolic acid-base disturbances?

Respiratory disturbances involve changes in carbon dioxide levels (e.g., respiratory acidosis or alkalosis), while metabolic disturbances involve changes in bicarbonate levels (e.g., metabolic acidosis or alkalosis).

How does hyperventilation lead to respiratory alkalosis?

Hyperventilation causes excessive carbon dioxide elimination, which lowers the partial pressure of carbon dioxide (pCO2) in the blood. This increase in pH is compensated by the kidneys lowering bicarbonate levels.