Bowel dysfunction is a common problem for adults and children, and yet many people do not seek help and when they do it is not up to standard. Unmanaged symptoms impact on the health of the patient, both physically and mentally, and add extra cost to the NHS. This article, by a clinical nurse specialist working with people suffering from bladder and bowl dysfunctions, will help healthcare professionals understand the possible causes of anatomical and functional bowel problems, especially constipation, and the conservative treatment interventions. This first article in a two-part series, explains anatomy and physiology of the lower gastrointestinal tract, what constitutes a normal bowel habit, frequency and variation. The second will focus on the causes of constipation, which are often misunderstood and misdiagnosed, and how they can be assessed and managed, as well as treatment options available.