Sigmoid colon

Definition

The sigmoid colon is the S-shaped section of the large intestine that connects the descending colon to the rectum. It plays a critical role in the final stages of digestion by storing fecal waste until it is ready to be expelled from the body. The sigmoid colon is highly vascularized and contains smooth muscle, which aids in peristalsis to move waste towards the rectum.

5 Must Know Facts For Your Next Test

1. The sigmoid colon is typically about 15-20 inches long and can vary in shape and position among individuals.
2. This part of the colon is named for its S-like shape, which allows it to efficiently store waste before elimination.
3. Due to its role in fecal storage, the sigmoid colon can become involved in conditions such as diverticulitis or colorectal cancer.
4. The sigmoid colon has a rich blood supply from branches of the inferior mesenteric artery, supporting its functions and health.
5. During a colostomy, the sigmoid colon may be brought out to create an opening in the abdominal wall, allowing for waste elimination outside the body.

Review Questions

• How does the structure of the sigmoid colon facilitate its function in waste storage and elimination?
  • The sigmoid colon's S-shaped structure provides a suitable space for storing fecal matter, allowing it to expand as it fills. Its smooth muscle layers enable peristalsis, which helps propel waste toward the rectum when it's time for elimination. The unique shape also prevents backflow, ensuring that waste moves efficiently through the digestive tract.
• Discuss the potential health issues related to the sigmoid colon and their implications on digestive health.
  • Health issues such as diverticulitis, where small pouches form and become inflamed, or colorectal cancer can significantly impact the sigmoid colon. These conditions can lead to symptoms like abdominal pain, changes in bowel habits, and serious complications if left untreated. Regular screenings and awareness of symptoms are crucial for maintaining digestive health and preventing serious outcomes related to these diseases.
• Evaluate the importance of blood supply to the sigmoid colon and how it supports its overall function in digestion.
  • The blood supply to the sigmoid colon, primarily from branches of the inferior mesenteric artery, is vital for its function as it delivers oxygen and nutrients necessary for maintaining healthy tissue. This rich vascularization supports processes like absorption and motility. Inadequate blood supply can lead to ischemia or compromised function, affecting waste management and overall digestive health.

Related terms

Descending colon: The part of the large intestine that runs downward from the transverse colon to the sigmoid colon, responsible for further absorption of water and salts.

Rectum: The final section of the large intestine that stores feces until they are expelled through the anus.

Peristalsis: The involuntary wave-like muscle contractions that move food and waste through the digestive tract.