1. Lining throughout the gastrointestinal system that consists of a mucous membrane that produces mucus and an underlying smooth muscle layer that contracts to move foot.
2. Mucous membrane that lines the respiratory tract. It warms and humidifies incoming air. It produces mucus to trap foreign particles.
3. Mucous membrane lining the inside of the bladder.
4. Mucous membranes lining the nasal cavity that warm and moisturize the incoming air. They also produce mucus to trap foreign particles.