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Histamine is an organic substance that is produced as part of a local immune response to cause inflammation. Histamine functions as a neurotransmitter and is responsible for and involved in local immunological responses. Additionally, it plays a role in the inflammatory process and mediates pruritus. Histamine is created by Basophils which are present in tissues that are close by and related. Histamine makes white blood cells more permeable, which enables infections to interact with the afflicted regions. Histamine causes many of the symptoms of allergies, such as a runny nose or sneezing.
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| Table of Content |
Key Terms: Histamine, Basophils, Mast Cells, Amino Acid, Immune System, Allergy, Allergic Reaction, Blood, Gastric Juice
What is Histamine?
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Histamine is a biological substance that is released by basophils and mast cells as a local defense against parasite intrusion or to shield cells from any foreign entity.
- Histamine is an amine chemical created when the amino acid histidine is decarboxylated.
- The word "amine" is derived from the chemical compound ammonia (NH3).
- The chemical formula of histamine is represented as C5H9N3.
- When a person is allergic to a particular substance, the immune system believes that the substance is harmful to the body.
- To protect the body, the immune system starts a chain reaction that prompts some of the body's cells to release histamine and other chemicals into the bloodstream.
- Histamine then acts on a person's eyes, nose, lungs, skin, or gastrointestinal tract, causing allergy symptoms.
- Antihistamine medications help to fight symptoms caused by the release of histamine during an allergic reaction.
Histamine
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| Human Health and Diseases | Difference between T cells and B Cells | Lymphocyte |
| Autoimmune Allergy | Sinusitis | Difference Between Granulocytes and Agranulocytes |
How was Histamine Discovered?
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Histamine was identified and synthesized in labs in the year 1907. Then, its roles in human physiology were determined. When an immune reaction is triggered by the arrival of a foreign entity or germ, this molecule is discovered in the cells. This is how our body automatically responds when something unwanted enters the body.
- Histamine triggers the immune response actions and makes the human body prepared for such incidents.
- Many cytological actions are initiated due to its formation that helps our body to cope with an immunological action and fight to eliminate the foreign body present in our system.
- Histamine is found in different forms in almost all animals.
Functions of Histamine
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Histamine is produced by an immune response in the local cells due to the presence of an unwanted particle or microbial invasion. It affects inflammatory and immunological reactions. Mast cells and basophils are where histamine is predominantly kept. It is secreted in reaction to tissue disruption brought on by trauma, illness, or allergies. The functions of histamine are:
Regulates Blood Flow
- The primary function of histamine is to regulate blood flow in the body where there is a lack of oxygen.
- This process is also called vasodilation in medical terms.
- It also helps in the expansion of arteries as a result of the blood vessel's muscle layer relaxing.
- Vasodilation is a method for improving blood flow to body parts that are deficient in air and/or nutrition.
- Due to increased blood vessel aperture size and vascular high energy, the blood pressure finally drops.
- Histamine binds to the endothelial cells of the veins, causing them to dilate and open up more to the blood cells.
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Helps Muscles to Relax
- Histamine relaxes some muscles, such as those found in the sidewalls of tiny blood arteries.
- It contracts other muscles including the smooth muscle cells in the lungs and intestines.
- Additionally, nasal congestion brought on by colds and allergic reactions to pollen is caused by histamine.
Production of Gastric Juice
- Gastric acid is produced in the stomach as a result of histamine release.
- This biochemical stimulant increases the blood circulatory system absorption rate of both water and carbon dioxide, which results in the creation of carbonic acid.
- The release of histamine regulates the timely production and release of gastric juice in the digestive system of the body.
- The digestive tract becomes hyper-acidified as a result of this acid being discharged into the gut.
Nasal Mucosal Effect
- The blood vessels in the tissue become more permeable as a result of histamine release.
- It results in an overflow of fluid escaping through the nose canal.
- This occurs when a foreign body enters the mucosal barrier and sets off an allergic reaction.
- Due to the secretion of histamine into the nasal part, the allergens are successfully removed.
- Histamine's function is to protect the nose and eyes by depositing fluid as a result of localized neuronal activation in these areas.
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Eliminating Allergic Diseases
- Through the unequal modulation of T helper cells, histamine is a key player in the pathogenesis of a number of allergic illnesses, including allergic rhinitis, and allergic asthma.
- The activation of mast cells by histamine is a key factor in many allergic disorders.
- In CD34+ cord plasma human mast cells, it may cause the production of leukotrienes, and chemokines via H4R.
- Histamine is a mediator of increased Th2 cytokine release and decreased Th1 cytokine secretion.
- Thus, by promoting a change towards Th2, histamine controls the adequate balance of both Th1 and Th2 cells.
Sleep-Wake Cycle
- The control of a person's sleep-wake cycle is likewise accomplished by histamine.
- It connects with the hypothalamus of the brain and functions as a transmitter.
- It is a component present in the human brain that regulates a person's sleep and waking cycles.
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| Related Topics | ||
|---|---|---|
| Muscular Tissue | Receptors | Thermoregulation |
| Infectious Diseases | Erythrocytes | Human Diseases |
Things to Remember
- Histamine is an organically produced substance that functions as a neurotransmitter and helps in the functioning of local immunological responses.
- Histamine is formed by the Basophils present in the white blood cells.
- The chemical formula of histamine is represented as C5H9N3.
- The primary function of histamine is the regulation of blood in the area of the body where oxygen is less also known as the vasodilation process.
- Histamine is used to fight a number of health ailments, including allergic rhinitis, and allergic asthma.
- The other functions of Histamine include helping muscles to relax, production of gastric juice, fighting and eliminating allergens, and regulating the sleep-wake cycle.
Previous Years’ Questions
- Histamine is secreted by… (JIPMER 2018)
- The predominant form of histamine present in human blood is… (JEE Main 2018)
- Histamine-secreting cells are found in… (NEET 1989)
- An insect bite may result in inflammation of that spot… (AIIMS 2008)
- During an allergic reaction, the binding of antigens to… (AIIMS 2009)
- Mast cells secrete… (AIPMT 2006)
- Endothelium is made up of…
- Allergens are…
- Which part of the pollen causes pollen allergy… (UP CPMT 2015)
- Due to increasing air-borne allergens and… (NEET 2019)
Sample Questions
Ques. What is the function of histamine in the process of blood circulation? (2 Marks)
Ans. The primary function of histamine is to regulate blood flow in the body where there is a lack of oxygen. Histamine's main side effect is the dilation of blood vessels, which results in swelling and redness in a region that is irritated. This occurs when a specific area is stressed or shocked as a result of an injury or the presence of an outside object.
Ques. What is the chemical formula of Histamine? (1 Mark)
Ans. The chemical formula of Histamine is C5H9N3.
Ques. What are the ways to increase histamine in the body? (2 Marks)
Ans. Histamine is found in many types of food which one can take to increase the flow of histamine in the body. Citrus fruits include things like pears, bananas, pineapple, strawberries, and bananas. Vegetables include things like beans, avocados, tomatoes, olives, and eggplant. Histamine is also found in yogurt and cheese.
Ques. What is the relation between drinking water and histamine? (2 Marks)
Ans. Water does aid in histamine clearance because more than 95% of extra histamines are eliminated from the body through the urine. Getting enough water allows your body to absorb histamines effectively while maintaining safe and healthy histamine concentrations.
Ques. Which tissue produces histamine? (1 Mark)
Ans. Histamine is created by basophils in the white blood cells.
Ques. Where is histamine found? (2 Marks)
Ans. Almost all animals contain the chemical histamine. In fact, certain plants and microbes also contain it. Its straightforward chemical composition has several applications in the various organ systems of complicated mammalian physiology.
Ques. What stimulates the release of histamine? (1 Mark)
Ans. Gastrin, vasoactive intestinal peptide, ghrelin, acetylcholine, and adrenaline interact with receptors on ECL cells to trigger the release of histamine.
Ques. What blocks the release of histamine? (1 Mark)
Ans. Antihistamines attempt to halt the allergic response by blocking histamine production.
Ques. Histamine is defined by which hormone? (1 Mark)
Ans. Histamine, a neurotransmitter, is represented by the pituitary hormone.
Ques. Why is histamine needed by the body? (2 Marks)
Ans. Like many other chemicals in the body, histamine has to be in equilibrium. When balanced, it helps regulate a variety of things, including discomfort, happiness, appetite, emotion, memory, blood pressure, concentration, and sleep/wake cycle.
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