Introduction to Blood: Which of the following is NOT regulated by blood?

• A. Body temperature (distribution of heat)
• B. Secretion of digestive enzymes into the small intestine lumen
• C. pH of body fluids (acid-base balance)
• D. Transport of respiratory gases (oxygen and carbon dioxide)

Answer: (B)

Verified step by step guidance

1. Step 1: Understand the role of blood in the body. Blood is a vital fluid that transports substances, helps regulate body temperature, maintains pH balance, and carries respiratory gases like oxygen and carbon dioxide.
2. Step 2: Analyze each option to determine if blood directly regulates it. For example, blood helps distribute heat to regulate body temperature, so it is involved in that process.
3. Step 3: Consider the pH of body fluids. Blood contains buffers that help maintain acid-base balance, so it plays a role in regulating pH.
4. Step 4: Look at the transport of respiratory gases. Blood carries oxygen from the lungs to tissues and carbon dioxide from tissues to the lungs, so it regulates this function.
5. Step 5: Evaluate secretion of digestive enzymes into the small intestine lumen. This process is controlled by the digestive system and hormones, not directly by blood, so it is NOT regulated by blood.