During Flight or Fight reaction, which of the following is responsible for increase in local blood flow :
**Core Concept**
The flight or fight reaction, also known as the sympathetic nervous system (SNS) response, is a physiological reaction that occurs in response to a perceived threat or stress. It is characterized by an increase in heart rate, blood pressure, and local blood flow to the muscles, preparing the body for action.
**Why the Correct Answer is Right**
The correct answer is responsible for vasodilation, which is the widening of blood vessels to increase blood flow. This is achieved through the release of neurotransmitters such as acetylcholine, which acts on muscarinic receptors to increase blood flow to the muscles. The sympathetic nervous system also releases epinephrine (adrenaline), which acts on alpha-1 adrenergic receptors to cause vasoconstriction in non-essential areas, but in skeletal muscle, it acts on beta-2 adrenergic receptors to cause vasodilation. This increase in local blood flow is essential for delivering oxygen and nutrients to the muscles during the flight or fight response.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it does not contribute to the increase in local blood flow during the flight or fight response.
* **Option B:** This option is incorrect because it actually causes vasoconstriction, which is the opposite of vasodilation.
* **Option D:** This option is incorrect because it is not directly involved in the increase in local blood flow during the flight or fight response.
**Clinical Pearl / High-Yield Fact**
The sympathetic nervous system's response to stress is characterized by an increase in heart rate, blood pressure, and local blood flow to the muscles, preparing the body for action. This response is mediated by the release of neurotransmitters such as acetylcholine and epinephrine, which act on specific receptors to achieve these effects.
**Correct Answer:** C