H2 receptors are a type of histamine receptor found in various tissues throughout the body. They play a crucial role in regulating gastric acid secretion in the stomach, as well as influencing blood vessel dilation and immune responses. When activated by histamine, H2 receptors help to increase the production of stomach acid, which is essential for digestion. In addition to their role in the digestive system, H2 receptors are also involved in the cardiovascular system. They can help to lower blood pressure by causing blood vessels to relax and widen. Medications known as H2 antagonists are often used to block these receptors, providing relief from conditions like gastroesophageal reflux disease (GERD) and peptic ulcers.