**Core Concept**
Glomus cells, also known as type I glomus cells, are specialized sensory cells that play a crucial role in detecting changes in oxygen levels in the body. They are part of the chemoreceptor complex, which is responsible for maintaining respiratory homeostasis.

**Why the Correct Answer is Right**
Glomus cells are found in the carotid and aortic bodies, which are located near the bifurcation of the carotid and aortic arteries, respectively. These cells contain oxygen-sensitive ion channels, such as the potassium channel, which allows them to detect changes in oxygen levels. When oxygen levels decrease, glomus cells depolarize and stimulate the surrounding chemoreceptor nerve fibers, leading to an increase in breathing rate. This response helps to restore oxygen levels in the body.

**Why Each Wrong Option is Incorrect**
**Option A:** The bladder does not contain glomus cells. The bladder is a hollow, muscular organ that stores urine, and its function is unrelated to oxygen sensing.
**Option B:** The brain does not contain glomus cells. While the brain is responsible for processing sensory information, including that from chemoreceptors, it does not contain glomus cells themselves.
**Option D:** The kidney does not contain glomus cells. The kidneys are responsible for filtering waste and excess fluids from the blood, but they do not contain specialized sensory cells like glomus cells.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that glomus cells are not found in the lungs themselves, but rather in the carotid and aortic bodies, which are located near the major arteries. This distinction is crucial for understanding the physiology of respiratory homeostasis.

**✓ Correct Answer: C. Chemoreceptors**