BIOL 4376 Lecture Notes - Lecture 50: Diphenhydramine, Antigen, Allergic Conjunctivitis
28 Jul 2020
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Document Summary
Histamine is in this group; an autacoid is a biological fact that acts locally and has a brief duration of action. Acts in a paracrine type of signalling. Agonists and antagonists are useful (histamines are antagonists) Synthesized from the amino acid histidine through decarboxylation. Indirect pathway (h2 receptor antagonists used to block) In the cns, we have histaminergic neurons; promoting wakefulness. First generation h1 antagonists get into the brain and block the cns action of histamine that promotes sedation. A response through histamine release through h1 receptors. Produces a redness or swelling like a mosquito bite. Not a prominent effect; not effective in acute bronchospasm. When the body comes in contact with an allergen, an antigen presenting cell binds that antigen and that promotes the immune response through helper t cells. First exposure: developing antibodies against the antigen. Second exposure: body remembers it and the antibodies form the 1st exposure bind up the antigen, releasing histamine.
