Approximately how many cells make up the adult human body?

• A. About 500 million
• B. About 100 billion
• C. About 1 million
• D. About 37 trillion

Answer: (D)

Verified step by step guidance

1. Step 1: Understand the context of the question. The problem is asking for an approximate number of cells in the adult human body, which is a fundamental concept in Anatomy & Physiology related to cellular biology.
2. Step 2: Recall that the human body is composed of trillions of cells, which vary in type and function, including red blood cells, neurons, epithelial cells, and more. These cells work together to maintain homeostasis and perform essential functions.
3. Step 3: Consider the scale of the human body. The adult human body is made up of a vast number of cells, far exceeding millions or billions. This is due to the complexity and size of the body, as well as the microscopic nature of cells.
4. Step 4: Compare the options provided. 'About 500 million' and 'About 1 million' are far too small to represent the total number of cells in the human body. 'About 100 billion' is closer but still significantly underestimates the actual number. The correct approximation is 'About 37 trillion,' which aligns with scientific estimates.
5. Step 5: Conclude that the adult human body contains approximately 37 trillion cells, a number derived from extensive research and calculations based on cell density, body mass, and average cell size.