Anatomy and Physiology Rectal Cancer

 

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Anat Anatomy omy and Physiolo Phys iology gy  The large intestine is a hollow tube that makes up the last 6 feet of the

dige digest stiv ive e tr trac act. t. It is of ofte ten n ref efer errred to as th the e larg large e bowe bowell or colo colon n (whi (which ch is technically just one part of the large intestine). The large intestine consists of the cecum (a pouch-like structure at beginning of the large intestine) colon rectum and anus. The colon and rectum are ne!t to other organs including the spleen liver pancr pan creas eas and repr reprodu oducti ctive ve and urinar urinary y or organ gans. s. "ach "ach of these these orga organs ns can be a#ected if colorectal cancer spreads beyond the large intestine.  

$tructure  The colon begins at the cecum where it joins the end of the small intestine (ileum).  The colon changes to rectal tissue in its last 6 inches. %ecause there is not a clear

 

border bor der betwee between n the colon colon and and rectu rectum m colon colon and recta rectall cancer cancers s are are grou grouped ped together as colorectal cancer.    The colon is divided into & parts' •

ascending colon  begins at the cecum where it joins the end of the small in inte test stin ine e and and tr trav avel els s upwa upward rd alon along g th the e righ rightt side side of th the e body body to th the e transverse colon

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transverse colon  connects the ascending colon to the descending colon and lies across the upper abdomen

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descending colon  connects the transverse colon and the sigmoid colon and lies along the left side of the body

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sigmoid colon  connects the descending colon and the rectum

   The colon and rectum are made up of a number of di#erent tissues organied organied into layers' •

mucosa

 

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inner lining (epithelium) lamina propria (connective tissue) and thin layer of muscle (muscularis mucosa)

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submucosa

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connective tissue glands blood vessels lymphatic vessels and nerves

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muscularis propria (muscular layer)

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serosa (serous layer)

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outer lining of the colon but not the rectum

  *esentery is a fold of tissue that connects organs to the body wall. +art of the colon is connected to the abdominal wall by mesentery. mesentery. The upper two-thirds of the rectum is also covered by mesentery called the mesorectum. The mesentery is made up of fatty connective tissue that contains the blood vessels nerves lymph nodes and lymphatic vessels that supply the colon. ,hen surgeons remove part of  the colon or rectum to treat cancer in these areas they will remove the mesentery ne!t to these organs as well. The lymph nodes within the removed mesentery will be e!amined to see if they contain cancer.

Function

 

 The main functions of the colon and rectum are to absorb water and nutrients from what we eat and to move food waste out of our body. •

 The colon receives partially digested food in a liuid form from the small intestine.

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%acteria (bowel ora) in the colon break down some materials into smaller parts.

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 The epithelium absorbs water and nutrients. It forms the remaining remaining waste into semi-solid material (feces or stool).

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 The epithelium also produces mucus at the end of the digestive tract which makes it easier for stool to pass through the colon and rectum.

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$ections of the colon tighten and rela! (peristalsis) to move the stool to the rectum.

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 The rectum is a holding area for the stool. ,hen it is full it signals the brain to move the bowels and push the stool from the body through the anus.

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bnormal 7ectal ectal cancer cancer is a malign malignant ant tumour tumour that starts starts in ce cells lls of the rectu rectum. m. *alignant means that it can spread or metastasie to other parts of the body. The rectum is a part of the digestive system. Together the colon and rectum make up the large intestine or large bowel. The colon takes up water and nutrients from food and passes waste to the rectum. 8ells in the colon and rectum sometimes change and no longer grow or behave normally. These changes may lead to benign tumors such as polyps which are not cancerous.

 

 

8hange 8hanges s to cells cells of the co colon lon and rectu rectum m can also also cause cause preca precanc ncer erous ous

conditions.. This means that the cells are not yet cancer but there is a higher chance conditions these thes e abnormal abnormal changes will become become cancer cancer.. The most common common pr precanc ecancero erous us condi con ditio tions ns of th the e co colon lon ar are e adeno adenomat matous ous polyp polyps s (also (also called called adenom adenomas as)) and polyposis syndromes. In some cases changes to colon and rectum cells can cause colorectal cancer.  

*ost often often rectal rectal cancer cancer starts starts in glandula glandularr cells cells which which make make mucus mucus and

digestive uids. These cells line the inside of the colon. This type of cancer is called adenocarcinoma of the rectum. 7are types of rectal cancer can also develop. These include carcinoid tumor lymphoma and sarcoma.