Large Intestine: Anatomy – Digestive System Organs (Nursing)

00:02 Now let's look at the large intestine, the next major organ of our digestive tract.

00:09 The large intestine has three unique features not seen anywhere else in the digestive system.

00:15 First we have the teniae coli which are three bands of longitudinal smooth muscle in the muscularis of the large intestine.

00:25 Also, we have these pocket like sacs caused by the tone of the tinea coli known as haustria.

00:34 Finally, we have the epiploic appendages which are going to be these fat filled pouches that are going to hang from the visceral peritoneum in the large intestine.

00:49 The cecum is going to be the first part of the intestine and where the contents of the small intestines are going to empty into the large intestine.

01:00 Also, just before the cecum.

01:04 We have the appendix.

01:06 This is a mass of lymphoid tissue that sits inferior to the cecum and the opposite direction of where food will be propelled.

01:16 The appendix is a part of that mucosal associated lymphoid tissue or MALT of the immune system.

01:24 It contains a bacterial storehouse that is capable of recolonizing the gut when necessary.

01:32 We'll talk about this shortly.

01:34 Also because of its twisted shape the appendix can be susceptible to blockages and this can lead to the condition known as appendicitis in some cases.

01:48 The large intestine is also referred to as the colon and is divided into the different regions.

01:57 So we have the ascending colon, which is going to travel up the right side of the abdominal cavity right at the level of the right kidney.

02:07 It then ends in a right turn known as the right colic flexure and it's sometimes called the hepatic flexure because it turns right at the liver.

02:18 Next we have the transverse colon.

02:21 This is going to transverse or travel across the abdominal cavity and it will end in a right angle turn known as the left kolok flexure or also, sometimes called the splenic flexure because it's going to turn right at the location of the spleen.

02:39 Finally, we have the descending colon, which is going to travel down the left side of the abdominal cavity.

02:46 This is followed by the sigmoid colon, which is the S shape portion.

02:51 That's now going to travel toward the pelvis.

02:54 And finally we have the rectum.

02:58 The rectum is going to contain three rectal valves that are able to stop feces from passing when gas passes through the rectum.

03:08 The rectum is then going to empty into the anal canal.

03:14 The anal Canal is the last segment of the large intestines and opens the body to the exterior at the anus.

03:23 The anal canal contains two sphincters as well.

03:26 It has an internal anal sphincter made up of smooth muscles and under involuntary control and an external anal sphincter made up of skeletal muscles under voluntary control.

03:42 So now let's take a microscopic view of our rectum and anus.

03:47 Our large intestines contain a thicker mucosa made up of a simple columnar epithelium, except in the anal canal where there there's going to be a stratified squamous epithelium.

04:02 The differences that anal canal needs to be able to withstand abrasion as feces is moving its way out of the body in the large intestines in the other parts of the large intestines we mostly are going to be specialized for absorption.

04:19 It does not have the circular folds and the Villi or the digestive secretions that we saw in the small intestine, but it does contain abundant deep crypts that have mucus producing goblet cells.

04:35 The mucosa of the anal canal remember the last part of the large intestine is actually going to hang down and long ridges or fold that we refer to as anal columns.

04:48 You can see this here and that image.