Acids, Bases, and Buffers

What are acids?

Substances that release H+ when they dissolve in water/in solution. Acids add H+

Give an example of an acid.

Hydrochloric acid (HCl). HCl in water dissociates (splits) into H+ and Cl-

What are bases?

Substances that remove H+ directly or by releasing hydroxides (OH-)1. Bases remove H+

How do some bases remove H+?

The hydroxide (OH-) released by some bases reacts with H+ in solution to produce water (H2O). This reaction removes the H+ from the solution

Give an example of a base.

Ammonia (NH3). It removes H+ directly by binding to it

Give another example of a base.

Sodium Hydroxide (NaOH). It removes H+ by releasing OH-, which reacts with the H+ producing water (it neutralizes the H+)

What is Ph?

Measure of the acidity of a solution

What does the acidity of a solution depend on?

The concentration of H+ (hydrogen cation, hydrogen ion, or a proton)

How is pH calculated?

pH = -log (H+ concentration)

What is the pH scale?

A 0-14 scale

What is the relationship between pH and H+ (acidity)?

Inverse: The lower the pH the more acidic; the higher the pH the less acidic.

What pH is very acidic?

1

What pH is not very acidic/very basic?

14

How does increasing H+ (acidity) affect pH?

It decreases pH. Acids add H+ to solution and decrease pH

How does decreasing H+ (acidity) affect pH?

It increases pH. Bases remove H+ from solution and increase pH

What is a neutral pH?

pH 7. This is an equilibrium between H+ and OH-

What is the normal pH range for most body fluids?

7.35-7.45

What happens if you cannot maintain pH within the normal range?

Disease

What is acidosis?

Body fluid pH chronically below 7.35

What is alkalosis?

Body fluid pH chronically above 7.45

What are buffers?

A buffer is a combination of a weak acid and its conjugate base or a combination of a weak base and it’s conjugate acid

What is the purpose of a buffer in a solution?

To resist changes in pH when acid or base are added to the solution

How do buffers work?

Because the buffer has both acid and base it can neutralize any added acid (with the base) or any added base (with the acid). Buffers essentially remove whatever was added and as a result prevent any changes in pH

Why are buffers important in body fluids?

Because they protect body fluids from large fluctuations in body fluid pH (which would be a lack of homeostasis)

What are the two buffer systems in the human body?

The Chemical Buffer Systems and The Physiological Buffer Systems

What are the Chemical Buffer Systems?

Buffers directly in body fluids. They can respond to added acid or base very quickly4. They can also be overwhelmed by too much added acid or base

What are the three chemical buffer systems in body fluids?

The Carbonic acid/Bicarbonate Buffer System, the Phosphate Buffer System, and the Protein Buffer Systembiscarbonate

Where is the Carbonic acid/Bicarbonate Buffer System located?

In the extracellular fluid (fluid outside cells)

Where is the Phosphate Buffer System located?

In the intracellular fluid (fluid inside cells)

Where is the Protein Buffer System located?

In the extracellular and intracellular fluid

What are the Physiological Buffer Systems?

Entire organ systems that act as buffers

What are the two Physiological Buffer Systems?

The Respiratory System and the Urinary System

How does the Respiratory System regulate the pH of body fluids?

By controlling the concentration of carbon dioxide (CO2

How does CO2 affect pH?

CO2 reacts with water to make acid in all body fluid and, as a result, can alter pH

How does the Urinary System regulate the pH of body fluids?

By saving or eliminating H+ and bicarbonate (a base) from the body in urine