Question

Imagine a friend tells you, “I heard that most people’s bodies are too acidic these days and we need to drink alkaline water to get ourselves back into balance.”

How would you respond? Include in your response information about our buffer system and information about the activity of either the lungs or kidneys.

Answer 1

The friend is having some misconceptions. The body maintains a balance between acid base system of the body through buffer systems, respiratory system and renal system.
If the blood becomes more acidic it is known as acidosis and if it becomes more alkaline it is known as alkalosis. Both these conditions are harmful to the body's proper functioning.
If we take too mych alkaline food it results in increase in bicarbonate level in blood which may result in alkalosis.
Maintenance of acid-base balance in body:

1. buffer system: There are three buffer system present in the blood. The bicarbonate buffer system is the main buffer. The other two are protein buffer system and phosphate buffer system.
The protein system uses hemoglobin, amino acid and plasma protein to maintain the blood ph.

Bocarbonate buffer system : The CO2 produced during cellular metabolic processes reacts with water to form H2CO3 in presence of carbonic anhydrase. H2CO3 rapidly dissociates into H+ and HCO3 - ions this maintaining acid base balance. H2CO3 is carried to lungs where it releases CO2. The CO2 is then expelled out of the body through expiration.
Resliratory system plays an important part in acid base balance. When the blood becomes to much acidic, chemoreceptors activates and signals the respiratory centre in the midbrain. The respiratory centre increases the rate and depth of breathing through increasing the activity of respiratory muscles. This causes removal of excess CO2 from the body. Removing the excess CO2 from body reduces formation of carbonic acid and restores acid base balance. Similarly when blood becomes more alkaline the rate of respiration decreases and results in increased level of CO2 in blood restoring the acid base balance.

- Kidneys sense too much H+ ions in the blood leading to acidosis. This causes the kidneys to increase HCO3- reabsorption and increase H+ secretion. This helps restore acid base balance.
When the blood becomes more alkaline due to increased bicarbonate in blood, kidneys reduce HCO3- reabsorption and reduce H+ excretion. This restores acid base balance in body.