The rectum's primary function is to store and temporarily hold feces (stool) before elimination from the body. Once the rectum is full, it signals the urge to defecate, ultimately expelling the waste through the anus.
Rectal Anatomy and Function in Detail
The rectum, located at the end of the large intestine, is a short, muscular tube approximately 15 cm (6 inches) long. It connects the sigmoid colon to the anal canal. Its function is not solely storage, however; some sources highlight a dual role:
- Storage: The rectum's main role is holding the stool until it's time for elimination. The rectum's distension by accumulating fecal matter triggers the urge to defecate. (Source: The rectum is a holding area for the stool. When the rectum is full, it pushes the stool out of the body through the anus.)
- Transportation (Conduit): The rectum also facilitates the movement of stool towards the anus. This transportation function is particularly relevant when the rectum isn't fully filled. (Source: CONCLUSION: The rectum has apparently two functions: transportation (conduit) and storage, both depending on the degree of rectal filling. If the fecal material is in a liquid or semiliquid form, the rectum mainly serves as a conduit.)
The rectum is crucial in the final stage of digestion. It receives waste material from the colon and, when full, initiates the process of elimination. (Source: The rectum is the lower part of the large intestine that connects to the sigmoid colon. It is about 15 cm (6 in) long. It receives waste from the colon and...) This process involves the coordinated action of rectal muscles and signals from the nervous system. (Source: Rectum acts as a temporary storage site for undigested food. It has voluntary smooth muscles that remove the faeces out of the body through the anus.)
It's important to note that the rectal gland in some species, like sharks, has a different, specialized function – namely, secreting a hypertonic sodium chloride solution. (Source: The rectal gland of the spiny dogfish, Squalus acanthias, secretes a fluid which is essentially a sodium chloride solution with a concentration about twice...; It is an epithelial organ in the intestine composed of tubules that serve a single function: the secretion of hypertonic NaCl.) This is distinct from the function of the human rectum.
