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.
Granulomatosis with polyangiitis (Wegenerâs) (GPA) is a rare disease of uncertain cause. It is the result of inflammation within the tissues called granulomatous inflammation and blood vessel inflammation ( vasculitis ), which can damage organ systems.asculitis is a general term that refers to inflammation of the blood vessels. When inflamed, the blood vessel may become weakened and stretch forming an aneurysm, or become so thin that it ruptures resulting in bleeding into the tissue.