Sequence of colour changes observed in Raynaud’s disease.
**Core Concept**
Raynaud's disease is a condition characterized by vasospasm of the digital arteries, leading to episodic reduction in blood flow to the extremities. This results in a sequence of color changes due to changes in blood flow and oxygenation.
**Why the Correct Answer is Right**
The sequence of color changes in Raynaud's disease typically begins with a white or pale color due to vasoconstriction and reduced blood flow. As the vasospasm worsens, the skin may turn blue or purple due to the presence of deoxygenated hemoglobin. Finally, as blood flow returns and oxygenation increases, the skin may turn red or pink.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as it does not accurately describe the sequence of color changes in Raynaud's disease.
**Option B:** This option is incorrect as it suggests a different sequence of color changes, which is not supported by clinical observations.
**Option C:** This option is incorrect as it does not accurately describe the sequence of color changes in Raynaud's disease.
**Clinical Pearl / High-Yield Fact**
It's essential to note that the sequence of color changes in Raynaud's disease can be triggered by exposure to cold temperatures or emotional stress, and can be accompanied by pain, numbness, or tingling in the affected extremities.
**Correct Answer:**
**D**. White (vasoconstriction) → Blue (deoxygenated hemoglobin) → Red (increased blood flow and oxygenation)