Acid-base balance: The physiology

Summary

This video provides a comprehensive overview of acid-base physiology, focusing on the regulation of blood pH in the body. It covers the roles of acids, bases, and hydrogen ions, explaining how they influence pH levels. Key buffering systems such as the bicarbonate, protein, hemoglobin, and phosphate buffers are explored, along with the respiratory and renal compensation mechanisms that help maintain pH stability. The script also highlights how the body responds to changes in pH, such as acidosis or alkalosis, through processes like bicarbonate reabsorption and hydrogen ion excretion, ensuring overall metabolic balance.

Takeaways

• 😀 Acids release hydrogen ions (H⁺), while bases bind to hydrogen ions, affecting the body's pH.
• 😀 The pH scale measures hydrogen ion concentration, with a normal blood pH range of 7.35 to 7.45.
• 😀 A pH above 7.45 indicates alkalosis, while a pH below 7.35 indicates acidosis.
• 😀 The main sources of hydrogen ions in the body are carbonic acid formation, protein metabolism, and organic acids like lactic and fatty acids.
• 😀 The bicarbonate buffering system is key in maintaining pH by binding excess hydrogen ions with bicarbonate to form carbonic acid.
• 😀 Respiratory compensation helps regulate pH by adjusting the rate of CO₂ removal from the body, affecting breathing patterns.
• 😀 If hydrogen ion concentration rises, breathing rate increases to expel CO₂, reducing acidity. If it decreases, breathing slows to retain CO₂ and increase acidity.
• 😀 Renal compensation takes longer (hours to days) and involves the kidneys reabsorbing bicarbonate and secreting hydrogen ions to restore pH balance.
• 😀 The kidney's role in acid-base balance is crucial, with reabsorption of bicarbonate in the proximal tubule and secretion of hydrogen ions in the distal tubules.
• 😀 High-protein diets, which increase the production of sulfuric and phosphoric acids, can lead to acidosis, requiring compensatory mechanisms to maintain pH homeostasis.

Q & A

What is the definition of an acid and a base in the context of acid-base physiology?

An acid is a substance that releases hydrogen ions, while a base is a substance that combines or attaches to hydrogen ions.

How is hydrogen ion concentration expressed in the human body?

Hydrogen ion concentration is expressed through the term pH, where a higher concentration of hydrogen ions corresponds to a lower pH and vice versa.

What is the normal pH range for blood?

The normal pH range for blood is between 7.35 and 7.45.

What happens when the blood pH is above 7.45 or below 7.35?

A pH above 7.45 indicates alkalosis, while a pH below 7.35 indicates acidosis.

What are the primary sources of hydrogen ions in the body?

The primary sources of hydrogen ions are carbonic acid formation from metabolically produced CO2, organic acids from nutrient breakdown (especially proteins), and organic acids like lactic acid and fatty acids.

How does the bicarbonate and carbonic acid buffering system work?

The bicarbonate and carbonic acid buffering system works by either attaching bicarbonate to hydrogen ions to form carbonic acid, or dissociating carbonic acid to release bicarbonate and hydrogen ions to restore the pH balance.

What is respiratory compensation and how does it work?

Respiratory compensation helps regulate pH by increasing or decreasing the rate of breathing to adjust CO2 levels. When hydrogen ions increase, breathing rate increases to expel CO2, which reduces hydrogen ion concentration.

How does renal compensation work in acid-base balance?

Renal compensation works by adjusting the levels of hydrogen ions, bicarbonate, and ammonia. The kidneys reabsorb bicarbonate to regulate pH and excrete hydrogen ions in the urine.

What is renal tubular acidosis and how does it relate to acid-base compensation?

Renal tubular acidosis occurs when the kidneys are unable to reabsorb enough bicarbonate, leading to acidosis. This can be classified into different types, such as type 2 renal tubular acidosis, which involves impaired bicarbonate reabsorption in the proximal convoluted tubule.

What happens in the case of a Western diet that increases hydrogen ions in the body?

A high-protein Western diet generates more hydrogen ions, leading to acidosis. The buffering system works to neutralize these hydrogen ions, and the kidneys compensate by reabsorbing bicarbonate and excreting more hydrogen ions into the urine.