**Anatomic Dead Space**

**Core Concept**
Anatomic dead space refers to the volume of air that remains in the airways and does not participate in gas exchange during breathing. This occurs due to the anatomical structure of the respiratory system, particularly the conducting airways.

**Why the Correct Answer is Right**
The anatomic dead space is primarily made up of the trachea, bronchi, and bronchioles. In a non-smoker under normal conditions, the anatomic dead space is approximately 150 mL. This is because the conducting airways are relatively large in diameter and have a low surface area-to-volume ratio, making them less efficient for gas exchange. The volume of the anatomic dead space is influenced by the height and body size of an individual.

**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because the anatomic dead space is not directly related to the functional residual capacity (FRC) of the lungs. While FRC is an important lung volume, it represents the volume of air remaining in the lungs at the end of passive expiration, not the volume of air not participating in gas exchange.

**Option B:** Incorrect because the anatomic dead space is not influenced by the presence of a smoker. Smoking can cause chronic bronchitis and emphysema, which can alter the anatomic dead space, but this is not relevant to a non-smoker under normal conditions.

**Option C:** Incorrect because the anatomic dead space is not directly related to the tidal volume (TV) of an individual. While TV is an important parameter in respiratory physiology, it represents the volume of air inhaled or exhaled during normal breathing, not the volume of air not participating in gas exchange.

**Clinical Pearl / High-Yield Fact**
In clinical practice, it's essential to understand the concept of anatomic dead space to accurately interpret pulmonary function tests and diagnose respiratory disorders. A high anatomic dead space-to-tidal volume ratio can indicate obstructive lung disease, while a low ratio may suggest restrictive lung disease.

**Correct Answer:** C. 150 mL