Patient X has slowed colonic motility, leading to unusually dry, compact faeces. Suggest a physiological explanation for why delayed transit through the large intestine causes this change in stool consistency.

Patient Y has a bacterial infection that causes rapid passage of material through the digestive tract, resulting in very watery faeces. Suggest why rapid transit through the colon causes this effect.

Explain the muscular actions that produce the coordinated physical mechanism responsible for moving a bolus of food along the alimentary canal.

Identify the specific anatomical structures of the human gastrointestinal tract where: (i) faeces are temporarily stored. (ii) faeces are ultimately expelled.

Distinguish clearly between the process of egestion and the process of excretion, with reference to their origins, the nature of the waste products, and their pathways of elimination.