Antihistamin (1): Histamin & patofisiologi alergi

Summary

This video discusses the pharmacology of antihistamines, starting with an explanation of histamine and its role in the body. Histamine is a small molecule produced by the body and stored in various cells, including mast cells and basophils. It plays a key role in allergic reactions, tissue damage, and responses to certain drugs and chemicals. The video explains how histamine is released in response to allergens, injuries, and specific substances like antibiotics and morphine, leading to physiological effects such as inflammation and vascular changes.

Takeaways

• 😀 Histamine is a small molecule produced in the body through decarboxylation of the amino acid histidine.
• 😀 Histamine is distributed in various tissues, especially in the skin, lungs, and digestive tract.
• 😀 The majority of histamine is produced and stored in mast cells, basophils, eosinophils, and enterochromaffin-like cells in the body.
• 😀 Histamine functions as an autocoid, meaning it is produced and acts locally in the body.
• 😀 Histamine is also referred to as a local hormone due to its localized production and action.
• 😀 Histamine can be released due to allergic reactions, particularly when an individual first encounters an allergen like pollen.
• 😀 Upon repeated exposure to an allergen, histamine is released when it binds to immunoglobulin E (IgE) antibodies on mast cells.
• 😀 Histamine can also be released as a result of tissue injury, where damaged cells release histamine and other mediators.
• 😀 The release of histamine in injured tissues affects blood vessels and nerves in the damaged area.
• 😀 Certain drugs and chemicals, such as antibiotics, poisons, dyes, and alkaloids like morphine, can directly trigger histamine release from granulocytes.

Q & A

What is histamine and how is it produced in the body?

Histamine is a small molecule produced by the body through the decarboxylation of the amino acid histidine. It is primarily distributed in various tissues, especially in the skin, lungs, and digestive system.

Where is histamine stored in the body?

Histamine is mainly stored in granulocytes, particularly in mast cells in tissues, basophils and eosinophils in the blood, and enterochromaffin-like cells in the stomach.

What is meant by histamine being an 'autocoid'?

As an autocoid, histamine acts locally within the body. It is produced and works in the same location, rather than being transported to other areas.

What are the three main conditions that can trigger histamine release?

The three conditions that can trigger histamine release are allergic reactions, tissue injury, and the presence of certain drugs or foreign chemicals.

How does an allergic reaction lead to histamine release?

In an allergic reaction, when an individual first contacts an allergen like pollen, the immune system activates and produces IgE antibodies. These antibodies attach to mast cells, and upon subsequent exposure to the allergen, it binds to IgE on mast cells, causing them to release histamine.

What role does histamine play in tissue injury?

In the event of tissue injury, damaged cells release mediators such as histamine. This can affect blood vessels and nerves in the injured area, contributing to inflammation and other responses.

Can histamine release be triggered by drugs or chemicals?

Yes, certain drugs and chemicals, such as toxins, antibiotics, dyes, and alkaloids like morphine, can directly trigger the release of histamine from granulocytes.

What is the function of histamine once it is released?

Once released, histamine causes various physiological responses, including vasodilation, increased blood flow, and increased permeability of blood vessels, which are part of the inflammatory response.

What is the relationship between mast cells and histamine release?

Mast cells are key players in the release of histamine. When they encounter an allergen that has bound to IgE antibodies on their surface, they undergo degranulation, releasing histamine into the surrounding area.

Why is histamine often associated with allergic reactions?

Histamine is a key mediator in allergic reactions, where it causes symptoms such as itching, swelling, and redness by triggering inflammation and other responses in the immune system.