The carotid body functions as: Answers: A=D A
A baroreceptor for blood pressure
B A temperature sensor
C A chemoreceptor for oxygen levels
D Alymph node
The correct answer and explanation is:
Correct Answer: C. A chemoreceptor for oxygen levels
The carotid body is a small cluster of cells located near the bifurcation of the carotid artery in the neck. It plays a crucial role in monitoring the chemical composition of blood, particularly the levels of oxygen. The primary function of the carotid body is to act as a chemoreceptor for oxygen levels, which means it detects changes in the concentration of oxygen in arterial blood.
When oxygen levels in the blood decrease (a condition called hypoxemia), the carotid body becomes activated. Specialized cells called glomus cells within the carotid body sense the drop in oxygen and respond by sending signals via the glossopharyngeal nerve (cranial nerve IX) to the respiratory centers in the brainstem. This triggers an increase in breathing rate and depth (hyperventilation), which helps restore normal oxygen levels in the blood.
In addition to oxygen, the carotid body also responds to changes in carbon dioxide (CO₂) levels and blood pH. High carbon dioxide levels or low pH (acidic blood) also stimulate the carotid body, resulting in respiratory compensation to expel CO₂ and correct the blood’s acidity.
The carotid body is not a baroreceptor (which would detect blood pressure changes), nor is it a temperature sensor, and it is definitely not a lymph node. Baroreceptors are found in the carotid sinus and aortic arch and are responsible for monitoring blood pressure, while temperature sensors are found throughout the body in skin and hypothalamic neurons. Lymph nodes, part of the immune system, filter lymph fluid and are unrelated to the carotid body.
Overall, the carotid body is vital for short-term regulation of respiratory activity in response to changing blood gas levels, helping maintain homeostasis in the body.