(USMLE topics, pharmacology) Functions of histamine, the 4 H-receptors, first and second generation H1-antihistamines. This video is available for instant download licensing here:
Histamine is most notoriously known as a mediator in important physiological processes such sleep and wake cycle, cognitive ability and food intake. it is present in all tissues but most abundant most of histamine in tissues is stored as granules inside mast cells. it is found in histaminergic neurons of the histamine exerts its action by binding to there are four h-receptors,
With different both h1 and h4 are involved in allergic inflammation, the major function of h2-receptor is to stimulate are used to treat gastric acid disorders such the term “antihistamine” generally refers to allergy-treating h1-antihistamines. mast cells that were previously sensitized histamine causes dilation and increased permeability contraction of smooth muscle;
And is responsible eyes, runny nose, sneezing, itching; to swelling, hives, and difficulty breathing due to bronchospasm. cause extensive vasodilation and bronchoconstriction instead, they bind to a different site on the first-generation h1-antihistamines derive adrenergic and serotonin antagonists, so they more importantly, they can cross the blood-brain in the brain,
Causing drowsiness, cognitive impairment and increased appetite. second-generation antihistamines are less they are also highly selective for h1-receptor and have no anti-cholinergic effects.
Transcribed from video
Histamine and Antihistamines, Pharmacology, Animation By Alila Medical Media