A common question about death is whether an individual loses control of their bowels. This query stems from natural curiosity about bodily functions and the physiological changes that occur when life ceases. Understanding the body’s waste elimination systems clarifies what happens when these controls are no longer active.
How the Body Controls Waste
The human body maintains precise control over bowel movements through coordinated voluntary and involuntary systems. This control primarily relies on the interaction of muscles and nerves in the pelvic region.
The internal anal sphincter is a smooth muscle that remains continuously contracted, involuntarily preventing the leakage of feces and gas. Its activity is regulated by the autonomic nervous system, with sympathetic nerves maintaining contraction and parasympathetic nerves causing relaxation. Conversely, the external anal sphincter is a skeletal muscle under conscious, voluntary control, allowing individuals to decide when to release stool. This control is enabled by the somatic nervous system, which innervates the external anal sphincter.
When the rectum fills with stool, stretch receptors send signals to the nervous system, initiating the defecation reflex. This reflex causes the internal anal sphincter to relax, while the external anal sphincter can be voluntarily tightened to delay defecation. If defecation is desired, the external sphincter relaxes, and coordinated contractions of the rectal and abdominal muscles help expel the waste.
Physiological Changes at Death
At the precise moment of death, a series of physiological changes begin to unfold in the body, directly impacting muscle control. The central nervous system ceases to function, leading to immediate and complete relaxation of all muscles throughout the body, a state known as primary flaccidity or primary relaxation. This relaxation extends to the sphincter muscles, which are no longer held in their contracted state by nervous impulses or the body’s energy reserves.
The loss of nervous system control means that the involuntary internal anal sphincter, which normally maintains tone, relaxes. Similarly, the voluntary external anal sphincter also relaxes. This widespread muscle relaxation, combined with any pressure from abdominal contents, can lead to the uncontrolled release of urine and feces. The initial relaxation is due to the immediate cessation of brain signals and the eventual depletion of adenosine triphosphate (ATP), the energy molecule required for muscle contraction and relaxation.
While rigor mortis, the stiffening of muscles after death, occurs later, the initial phase is characterized by this universal relaxation. The relaxation of sphincters is one of the earliest post-mortem changes, occurring almost immediately. This physiological reality means that if there is waste material in the rectum and colon at the time of death, its release is a natural consequence of the body’s systems shutting down.
Factors Affecting Post-Mortem Bowel Release
While the relaxation of sphincters at death creates the potential for bowel release, it does not happen in every case. Several factors influence whether or not this occurs, or the extent of it. The primary determinant is the presence and amount of fecal matter in the lower digestive tract at the time of death. The human digestive process can take a considerable amount of time; food typically moves through the stomach and small intestine within 6 to 8 hours, but it can remain in the large intestine for up to 36 to 48 hours, or even up to 5.5 days, before being eliminated.
Therefore, if the colon and rectum are relatively empty at the moment of death, there may be little to no bowel movement. Factors such as the individual’s diet, overall health, and the timing of their last bowel movement before death all play a role in the contents of their digestive tract. For instance, someone who has not eaten for an extended period or has recently had a bowel movement might have an empty lower colon.
The cause of death can also be a contributing factor, though less directly than the presence of waste. Conditions that lead to prolonged illness or starvation may result in a relatively empty bowel. Conversely, sudden death, especially if it occurs shortly after a meal, might increase the likelihood of bowel contents being present. The body’s position after death can also influence the direction of any released material due to gravity.