10/2: pH & the buffer system

Tanya Paull

• Professor in Molecular Genetic & Microbiology

• Research in the Paull lab is focused on DNA damage response in eukaryotic cells, specifically the checkpoint aviation and DNA repair responses 

• Thiamine deficiency can lead to the formation of reactive oxygen species 

pH

• -log[H^+]

• A measure of hydrogen ion concentration [H^+]

H^+

• 10^-pH

pH + pOH =

14

What is the relationship between H^+ and pH?

• Acidic = low pH and high H^+

• Basic = high pH and low H^+

Normal blood pH

• 7.35 to 7.45

What is acidosis?

• Low pH

• Less than 7.35

• Too Acidic 

  • Losing too many bicarbonate (base)

• When getting acidosis, you’re increasing the amounts of hydrogen in your system 

What are the causes of acidosis?

• Diarrhea

• Kidney failure

• Elevated CO2 due to asthma, emphysema, etc

What are symptoms of acidosis?

• Inhibits brain, muscle fatigue, coma

What is alkalosis?

• High pH

• Higher than 7.45

• Basic 

• Expelling too much acidic vomit or you’re retaining too much base

What are the causes of alkalosis?

• Vomiting

• Breathing too quickly 

• Panic attack, fever, etc

What are symptoms of alkalosis?

• Excites brain, muscle twitch, convulsions

How do our bodies respond to changes in pH? Vomiting

• Losing too much stomach acid so you become more basic 

How do our bodies respond to changes in pH? Eugene and Metabolic acidosis

• When glucose is not available, adipose tissue (fat) and/or certain amino acids are broken down in a way that generates acidic ketones

• Alcohol can also promote keystone (acidic) production by impairing the liver’s ability to make glucose

How do our bodies respond to changes in pH? Diarrhea

• Cause you to lose too many bicarbonate ions (base), so you become more acidic

How do our bodies respond to changes in pH? Breathing

• If blood pH decreases (becomes more acidic): Breathing becomes faster and deeper to remove more carbon dioxide (CO₂). This decreases CO₂ in the blood, reduces H⁺ concentration, and raises pH.

• If blood pH increases (becomes more basic): Breathing may slow down to retain more CO₂. This increases H⁺ concentration and lowers pH.

Urine pH

• 4.5 to 8

Le Chatelier’s principle

• If a chemical system at equilibrium experiences a change, then the equilibrium shifts to counteract the imposed change and a new equilibrium is established 

List of buffers

• Carbonic acid/bicarbonate system, protein buffers, phosphate buffers, hemoglobin

Carbonic acid system

• More H^+ → Lower pH (acidic)

• Less H^+ → higher pH (more basic)

Ketogensis

• The process by which the liver produces ketone bodies from fat when the body does not have enough glucose (sugar) available for energy

• How it work

  • Low glucose availability

  • Fat breakdown: The body breaks down stored fat into fatty acids

  • Ketone production: The liver converts fatty acids into ketone bodies

  • Energy use: The brain, muscles, and other tissues can use ketone bodies for energy

• Ketogenesis is a normal metabolic process but excessive ketone production combined with uncontrolled diabetes can lead to diabetic ketoacidosis (DKA)

Ketosis

• A state in which ketones are elevated in the blood

A buffer system ___ the potential shift in pH caused by an excess acid or base in the body

limits

What is the bicarbonate system?

The bicarbonate buffer system helps maintain a stable pH in the blood by preventing it from becoming too acidic or too basic.

It involves three substances:

• Carbon dioxide (CO₂)

• Carbonic acid (H₂CO₃)

• Bicarbonate (HCO₃⁻)

What causes carbonic acid to form in the blood?

Carbonic acid forms when carbon dioxide combines with water in the blood.

Here is the process:

1. Your body cells produce CO₂ during cellular respiration.

2. CO₂ enters the blood.

3. CO₂ combines with water (H₂O).

4. This reaction produces carbonic acid (H₂CO₃).

5. Carbonic acid can separate into hydrogen ions (H⁺) and bicarbonate ions (HCO₃⁻).

How to does lung affect pH?

• Regulate CO2 by changing breathing rate

How does kidney affect pH?

• Regulate H^+ and bicarbonate