Final answer:
The dominant immunoglobulin at mucosal surfaces is IgA, which is primarily secreted in dimeric form and helps trap and neutralize pathogens, thereby protecting mucosal membranes.
Step-by-step explanation:
The dominant immunoglobulin synthesized at mucosal surfaces is IgA.Immunoglobulins, or antibodies, are produced by the immune system to help protect against pathogens. The mucosal immune system primarily secretes dimeric immunoglobulin A (IgA), which is the predominant immunoglobulin found in mucosal secretions like saliva, tears, breast milk, and gastrointestinal and respiratory tract secretions.
This dimeric IgA operates by trapping and neutralizing pathogens, thus preventing their attachment to mucosal surfaces and subsequent infection. In contrast, IgM is secreted to a lesser extent at these surfaces. However, IgA's abundant presence and specialized structure make it particularly efficient at binding to pathogens and forming a protective barrier in mucosal areas; it is designed for secretion in bodily fluids and is critical for bodily defense.