Which of the following factor increases gastric motility?
**Core Concept**
Gastric motility refers to the rhythmic contractions of the stomach muscles that mix food with gastric juices and propel it into the small intestine for further digestion. Various factors can influence gastric motility, including hormonal, neural, and mechanical stimuli.
**Why the Correct Answer is Right**
The correct answer is **C. Acetylcholine**. Acetylcholine is a neurotransmitter released by the vagus nerve that stimulates the muscarinic receptors on the smooth muscle cells of the stomach, leading to increased gastric motility. This is an example of parasympathetic stimulation, which increases gut motility and secretions. Acetylcholine also stimulates the release of gastrin, a hormone that further enhances gastric acid secretion and motility.
**Why Each Wrong Option is Incorrect**
**Option A:** **Vasopressin** is a hormone that decreases gastric motility and secretions by stimulating the release of somatostatin, which inhibits gastrin and acetylcholine release.
**Option B:** **Gastric inhibitory polypeptide (GIP)**, also known as glucose-dependent insulinotropic polypeptide, is a hormone that inhibits gastric motility and secretions in response to nutrient intake.
**Option D:** **Somatostatin** is a hormone that inhibits the release of gastrin and acetylcholine, leading to decreased gastric motility and secretions.
**Clinical Pearl / High-Yield Fact**
The vagus nerve plays a crucial role in regulating gastric motility and secretions. Damage to the vagus nerve, such as that seen in vagotomy or diabetes, can lead to delayed gastric emptying and decreased gastric motility.
**Correct Answer:** C. Acetylcholine