The vomiting reflex is primarily controlled by the vomiting center located in the medulla oblongata of the brain.
The medulla oblongata, a crucial part of the hindbrain, acts as the main control center for vomiting. It receives input from various sources, including:
- The chemoreceptor trigger zone (CTZ): Located in the area postrema of the medulla, outside the blood-brain barrier, the CTZ detects toxins and drugs in the bloodstream.
- The gastrointestinal tract: Irritation or distension of the stomach and intestines can trigger vomiting signals.
- The vestibular system: Inner ear disturbances, such as those caused by motion sickness, can activate the vomiting center.
- Higher brain centers: Emotional stress, pain, and even sights or smells can induce vomiting.
Once the vomiting center is activated, it coordinates a series of physiological events that result in vomiting, including:
- Increased salivation
- Retroperistalsis (reverse muscle contractions) in the small intestine
- Relaxation of the lower esophageal sphincter
- Forcible contraction of the abdominal muscles and diaphragm, which increases intra-abdominal pressure and expels stomach contents.
Therefore, while various factors can trigger vomiting, the central control lies within the vomiting center in the medulla oblongata.
