Cyanosis is caused by
A. blushing or embarrassment B. consuming too many carrots C. over-exposure to UV light D. lack of oxygen E. exposure to carbon monoxide
The correct answer and explanation is:
The correct answer is D. lack of oxygen.
Cyanosis is a bluish discoloration of the skin, especially around the lips, fingers, and toes, and it occurs when there is a decrease in the oxygen levels in the blood. This happens because when the oxygen levels drop, the blood becomes less oxygenated, and the deoxygenated hemoglobin in the blood has a blueish tint, leading to the visible discoloration of the skin.
There are two main types of cyanosis: central cyanosis and peripheral cyanosis. Central cyanosis is more commonly associated with heart or lung diseases that prevent oxygen from being effectively transported into the blood. Conditions like chronic obstructive pulmonary disease (COPD), pneumonia, or congenital heart defects can result in central cyanosis. Peripheral cyanosis, on the other hand, is usually due to reduced blood flow to the extremities, which can occur in conditions such as hypothermia or shock.
Cyanosis typically occurs when oxygen saturation levels in the blood fall below about 85%. However, not all forms of low oxygen saturation cause cyanosis, and in some cases, people may not show visible signs even when oxygen levels are low. Cyanosis is often an indicator of an underlying medical issue that requires further evaluation.
For example, carbon monoxide poisoning (option E) can prevent oxygen from binding to hemoglobin, but it often does not cause cyanosis since carbon monoxide binds more readily to hemoglobin than oxygen, giving the blood a bright red color instead of the blue color associated with deoxygenated blood. Similarly, excessive exposure to UV light or consumption of large amounts of carrots (options B and C) would not lead to cyanosis; these are unrelated to oxygen levels in the blood.