Final answer:
An injection of histamine activates the body's immune response, causing increased blood flow, vessel permeability, and triggering symptoms like itching, swelling, and inflammation. These are defense mechanisms against pathogens but can lead to discomfort in allergic reactions. Antihistamines and treatments like hydrocortisone cream are used to alleviate these symptoms by reducing histamine production or blocking its effects.
Step-by-step explanation:
An injection of histamine triggers a range of physiological responses as part of the body's defense mechanism. Primarily, histamine is involved in local immune responses and regulates physiological functions in the gut, as well as acting as a neurotransmitter. When histamine is released in the body, it causes an increase in blood flow to the affected area and the permeability of blood vessels. This can result in symptoms such as inflammation, itching, and swelling, which are common in allergic reactions.
For instance, histamine stimulates mucus secretion, causes vasodilation that can lead to hives and hypotension, and prompts bronchiole constriction which may result in wheezing and difficulty breathing. It interacts with nerve endings causing itching and sneezing, and can lead to stomach discomfort and diarrhea due to the relaxation of intestinal smooth muscles. Understanding the role of histamine is crucial for medical professionals when diagnosing and treating allergic reactions and other conditions involving the immune system. Treatments may include the use of antihistamines to counteract these effects by blocking histamine receptors.
Clinical applications such as the use of hydrocortisone cream aim to reduce the production of histamine, thereby suppressing inflammation and symptoms like pruritus. However, it's essential to note that such treatments may only address the symptoms and not the underlying cause of allergic reactions.