Acetylcholine is released from a presynaptic neuron into the synaptic cleft. Once in the synaptic gap, acetylcholine can: - Bind to presynaptic receptors: presynaptic activation or inhibition leads to automodulation of the presynaptic cholinergic neuron.
When welts are a sign of a medical problem, they are usually accompanied by other symptoms which provide clues to the problem. Physical trauma such as a blow can cause a welt, and welts can also be caused by allergic reactions, infections, injections, insect bites, and skin reactions, in very sensitive people. For example, in people with dermographism, even a gentle touch to the skin can cause a welt to emerge.
So if you have a mysterious bump on your skin, here are ten common skin conditions that could be responsibleâ¦. Hives develop as an allergic reaction to food, environmental surroundings (i.e., dust), or medication. They form a rash of annoying and raised itchy welts that can also burn. Hives will appear anywhere on the body in a few raised spots or they will join together to create one larger patch of raised, itchy skin that can last up to a few days.