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.
Hives are a skin rash condition known medically as urticaria. Hives are a type of skin allergy or rash that is caused by an allergen in most cases. Hives are raised welts on the skinâs surface that are generally circular with a pale center and red halo. These welts can be different sizes and shapes, and can be found on any part of the body. There are many types of hives, and hives causes vary based on the type of hives experienced. What Are The Symptoms of Hives? The symptoms of hives include itching in most cases, swelling of the area, red welts that look much like a mosquito bite.