**Question:** In triple response, flare is mediated by which reflex?

**Core Concept:** The triple response is a sequence of reflexes triggered by a noxious stimulus. It consists of the initial withdrawal reflex, the secondary protective reflex, and the tertiary reflex (flare, diapedesis, and elevation). The flare response is an early part of the triple response that involves vasodilation and increased blood flow to the area of injury, preparing the body for wound healing.

**Why the Correct Answer is Right:** The correct answer is A: **Von Frey Hairs**. Von Frey hairs are a type of tactile stimulus that can elicit the triple response, including the flare response. They are thin, flexible filaments that apply varying amounts of force on the skin, simulating different levels of pressure. When a Von Frey hair stimulates a sensitive nerve ending, it triggers the initial withdrawal reflex, followed by the secondary protective reflex, and finally, the tertiary response (flare, diapedesis, and elevation).

**Why Each Wrong Option is Incorrect:**

B: **Cutaneous nociceptors** are sensory receptors that detect pain and pressure stimuli, but they are not specific enough to elicit the triple response. Cutaneous nociceptors are involved in pain perception and may contribute to the secondary and tertiary responses, but they are not the primary stimulus for the flare response.

C: **Spinal reflex arc** is a component of the spinal cord's reflex pathway, but it is not the correct answer for the triple response in general. While the spinal reflex arc plays a role in the triple response, it is too broad to specifically address the flare response mediated by Von Frey hairs.

D: **Hair follicle receptors** are mechanoreceptors that detect changes in tension and pressure, but they are not the correct answer for the triple response triggered by Von Frey hairs. Hair follicle receptors are involved in pressure and touch sensing but are not responsible for the flare response elicited by Von Frey hair stimulation.

**Clinical Pearl:** The triple response is an essential part of the body's defense mechanism, helping to protect damaged tissue and initiate the healing process. By understanding the triple response, students of medicine and other healthcare professionals can better comprehend the body's response to injury and pain, which is crucial for patient care and treatment.