Question

Are the following examples of body fluids acidic, basic, or neutral? a. saliva, \(\mathrm{pH} 6.8\) b. urine, \(\mathrm{pH} 5.9\) c. pancreatic juice, \(\mathrm{pH} 8.0\) d. bile, \(\mathrm{pH} 8.4\) e. blood, \(\mathrm{pH} 7.45\)

Short answer

Saliva: slightly acidic, Urine: acidic, Pancreatic juice: basic, Bile: basic, Blood: slightly basic.

Step-by-step solution

- Understanding pH scale

The pH scale ranges from 0 to 14. A pH of 7 is considered neutral. A pH less than 7 is acidic, and a pH greater than 7 is basic or alkaline.

- Classify saliva

Saliva has a pH of 6.8. Since it is less than 7 but close to neutral, it is slightly acidic.

- Classify urine

Urine has a pH of 5.9. Since this pH is less than 7, urine is acidic.

- Classify pancreatic juice

Pancreatic juice has a pH of 8.0. Since this pH is greater than 7, pancreatic juice is basic.

- Classify bile

Bile has a pH of 8.4. Since this pH is greater than 7, bile is basic.

- Classify blood

Blood has a pH of 7.45. Since this pH is slightly greater than 7, blood is slightly basic.

Key concepts

Acidic Body Fluids

Body fluids are classified as acidic when their pH level is below 7. Acids have a higher concentration of hydrogen ions (H^+). This means acidic fluids have more free H^+ ions compared to basic fluids.
Examples of acidic body fluids from the exercise:

• Saliva: With a pH of 6.8, saliva is slightly acidic. It helps break down food particles in our mouth.
• Urine: With a pH of 5.9, urine is also acidic. The acid in urine helps remove waste and maintain body fluid balance.

Understanding the acidity of body fluids is important because it can affect enzyme activity and overall body function.
High acidity can be harmful and may lead to conditions like acidosis.

Basic Body Fluids

Basic or alkaline body fluids have a pH level above 7. They have a lower concentration of hydrogen ions (H^+) and more hydroxide ions (OH^-).
Examples of basic body fluids from the exercise:

• Pancreatic juice: With a pH of 8.0, pancreatic juice is basic. It helps neutralize stomach acid and enables digestive enzymes to function properly in the small intestine.
• Bile: With a pH of 8.4, bile is also basic. It's produced by the liver and helps digest fats by breaking them down into smaller molecules.
• Blood: With a pH of 7.45, blood is slightly basic. It is crucial for transporting nutrients and oxygen to cells and removing waste products.

It is essential to maintain a balance between acidic and basic fluids in the body for proper metabolic function and to prevent conditions like alkalosis.

pH Scale

The pH scale measures how acidic or basic a substance is, ranging from 0 to 14.

• A pH of 7 is neutral, meaning there is an equal concentration of hydrogen ions (H^+) and hydroxide ions (OH^-).
• pH values less than 7 indicate acidity, where there are more hydrogen ions (H^+).
• pH values greater than 7 indicate alkalinity or basic nature, where there are more hydroxide ions (OH^-).

The pH scale is logarithmic, meaning each unit represents a tenfold change in concentration.
For instance, a pH of 6 is ten times more acidic than a pH of 7, and a pH of 8 is ten times more basic than a pH of 7.
Understanding the pH scale is crucial for interpreting the acidity or basicity of body fluids and how it affects biological functions.
pH balance in the body is critical for processes such as enzyme activity, digestion, and overall homeostasis.