Sympathetic stimulation causes all except
**Core Concept**
Sympathetic stimulation is a key component of the body's "fight or flight" response, mediated by the sympathetic nervous system. This response involves the release of various neurotransmitters, including norepinephrine, which activate adrenergic receptors to produce physiological effects.
**Why the Correct Answer is Right**
Sympathetic stimulation causes an increase in heart rate (tachycardia) due to increased sympathetic innervation to the sinoatrial node and enhanced beta-1 adrenergic receptor activity. This leads to increased contractility of the heart muscle and increased cardiac output. Additionally, sympathetic stimulation causes dilation of the pupils (mydriasis) due to the activation of alpha-1 adrenergic receptors in the iris sphincter muscle.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is not provided.
**Option B:** This option is not provided.
**Option C:** This option is not provided.
**Option D:** This option is not provided.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that sympathetic stimulation can also cause vasoconstriction in certain vascular beds, such as skeletal muscle, due to alpha-1 adrenergic receptor activation, while causing vasodilation in others, like the skin, due to beta-2 adrenergic receptor activation.
**Correct Answer:** D.