inherent desire for privacy among humans. Freud stipulated a second stage of development, the Anal Stage, which centers around the release of waste from the bladder and bowels. He categorized two types: anal retentive and anal expulsive. See also Artist's Shit Ecological sanitation Hemorrhoid Human waste Improved sanitation Rectal tenesmus - a feeling of incomplete defecation Reuse of human excreta Shit Sustainable sanitation Urination References Further reading Eric P. Widmaier; Hershel Raff; Kevin T. Strang (2006). Vanders' Human Physiology: The Mechanisms of Body Function. Chapter 15. 10th ed. McGraw Hill. . Excretion Digestive system Medical signs Feces Symptoms and signs: Digestive system and abdomen