Rectum

Your body has a straight part inside.

It is part of your gut. This part holds waste for a little while. It waits there before you go to the bathroom.

When the part gets full, your body feels it. This tells you it is time to go. Muscles help push the waste out. This helps keep your body clean and healthy. It is a very important job!

The rectum is a part of your gut. It is the last straight part of the large intestine.

Its main job is to store waste. This waste is called feces. The rectum holds it for a short time. It waits there before it leaves the body.

As waste moves in, the walls of the rectum stretch. Tiny sensors in the walls feel this stretch. These sensors tell your brain that it is time to go to the bathroom. This set of steps is called defecation.

To help the waste move out, muscles in the rectum contract. These are muscle movements that push.

Special muscles called sphincters help keep waste inside. They stay closed so you do not leak. When you are ready, these muscles relax. The waste then moves through the anal canal.

Doctors can study the rectum using a small camera. They call this a colonoscopy. This helps them make sure everything is healthy.

The rectum is the final straight part of the large intestine. It plays a very important role in how our bodies work. Its main job is to act as a temporary storage site for feces. This waste material moves into the rectum from the descending colon. It stays there for a short time before it is released. This process helps our bodies manage when we need to go to the bathroom.

This part of the gut works through a series of steps. First, regular muscle contractions called peristalsis move waste into the rectum. As the rectum fills up, its walls begin to expand. Tiny stretch receptors in the rectal walls sense this change. These receptors send signals to the nervous system to create the urge to pass feces. This whole way it works is called defecation. To help the waste move out, the muscles of the rectum contract.

Humans have learned a lot about this part of the body over time. The name comes from the Latin words rectum intestinum. This phrase means straight intestine. Much of what we know comes from very detailed studies. One famous person was Andreas Vesalius, who shared descriptions in 1543. Long ago, a physician named Galen also studied anatomy. He looked at animal corpses to see how different guts were shaped.

There are many specific details about how the rectum is built. The adult human rectum has a certain length and connects to the sigmoid colon. It ends in a wider section called the rectal ampulla. This ampulla is a cavity that helps with storage. The blood supply changes depending on where you look in the rectum. The top two thirds get blood from the superior rectal artery. The bottom third gets blood from the middle and inferior rectal arteries.

Doctors use many tools to check if the rectum is healthy. They might use a colonoscopy, which uses a guided camera to look inside. They can also use CT scans or MRI scans to see images. Sometimes, a doctor might take a rectal temperature with a thermometer. This is often a bit higher than the temperature in your mouth. Doctors also use the rectum to give certain medicines. These can be shaped like small pieces called suppositories.

The rectum is the final straight section of the large intestine in humans and some other mammals. It plays a vital role in the gastrointestinal tract by serving as a temporary storage site for feces. This organ is located at the end of the sigmoid colon and leads into the anal canal. By holding waste material, the rectum allows the body to manage the timing of waste expulsion. This process is essential for maintaining regular bodily functions and controlling when waste leaves the system.

The mechanism of the rectum relies on a coordinated series of muscular and nervous system actions. First, waste material moves from the descending colon into the rectum through peristalsis. Peristalsis refers to the regular, wave-like muscle contractions that push material through the gut. As the rectum fills, its walls expand. This expansion triggers stretch receptors located within the rectal walls. These receptors send signals to the nervous system, creating the urge to defecate. When rectal pressure increases beyond 18 mmHg, the urge to defecate becomes voluntary. If pressure reaches 55 mmHg, a reflex expulsion of the contents occurs.

To prevent leakage, the body uses several biological structures. An internal anal sphincter and an external anal sphincter work together to keep feces contained. Additionally, the puborectalis muscle stays in a state of resting contraction. During voluntary defecation, the external anal sphincter relaxes along with the puborectalis muscle. This relaxation changes the angle between the rectum and the anus, making it straighter. This straight path facilitates the efficient passage of waste through the anal canal.

The anatomy of the rectum is quite specific and changes in shape. An adult human rectum begins at the rectosigmoid junction, near the third sacral vertebra. While its diameter is similar to the sigmoid colon at the start, it widens at the end. This dilated section is called the rectal ampulla, which functions as a storage cavity. The ampulla is shaped similarly to a Roman ampulla. The rectum then terminates at the anorectal ring or the dentate line. Beyond this, the anal canal continues for a short distance before the gastrointestinal tract ends at the anal verge.

The internal structure, or microanatomy, of the rectal wall is complex. It features a mucosa lined with a single layer of column-shaped cells. Interspersed among these are goblet cells, which secrete mucus. There is a higher concentration of these goblet cells in the rectum than in other parts of the gastrointestinal tract. Beneath the mucosa lies the lamina propria and a smooth muscle layer called the muscularis mucosa. This is followed by the submucosa of connective tissue and the muscularis propria. The muscularis propria consists of two distinct muscle bands: an inner circular band and an outer longitudinal one.

Blood supply to the rectum is divided into different zones. The upper two-thirds of the rectum receive blood from the superior rectal artery. This artery is a continuation of the inferior mesenteric artery. The lower third is supplied by the middle and inferior rectal arteries. As the superior rectal artery crosses the pelvic brim, it enters the mesorectum at the level of the S3 vertebra. It then splits into branches that run along the sides and back of the rectum. These branches eventually connect with the middle and inferior rectal arteries within the submucosa.

Our understanding of the rectum has evolved through historical study. The name comes from the Latin "rectum intestinum," meaning straight intestine. This was a translation of the Ancient Greek term used by the physician Galen. Galen observed the rectum in animal corpses and noted it was straight. However, the term "straight" is not technically accurate for the human rectum. Much of the modern anatomical knowledge we use today comes from Andreas Vesalius. He provided highly detailed descriptions of the human body in 1543. Medical professionals still use various tools today, such as colonoscopies and MRI scans, to examine this region.