Question

1) Describe the structure and function of a sphincter. State the names and locations of the sphincter in GI tract
2) what are the functions of the following
a) mesentery
b)mesocolon
c)falciform ligament
d)greater omentum

Answer 1

1.

1. upper esophageal sphincter (UES)- allows the food through esophagus and prevents air from entering the esophagus at the same time. Food is pushed through this sphincter during swallowing
2. cardiac sphincter (LES)- found at the base of the esophagus where it meets the stomach. Prevents backflow of material
3. pyloric sphincter- prevents backflow of chime from the duodenum into the stomach. Regulates release of chyme (creamy mixture of food and gastric juices) so that there is a steady flow of food into the small intestine for several hours after eating.
4. ileocecal sphincter- the remainings of the chyme is passed through the ileocecal sphinter into the large intestine.
5. involuntary anal sphincter- produces the urge to defecate
6. voluntary anal sphincter- responsible for defecating and expelling the feces that remain after digestion and absorption has occurred.

2.

1. Mesentery: binds the jejunum and ileum of small intestine to posterior abdominal wall; laden with fat and contributes extensively to large abdomen in obese.

2. Mesocolon: binds the transverse colon and sigmoid colon of large intestine to posterior abdominal wall; carries blood & lymphatic vessels to intestines (mesocolon & mesentery hold intestines loosely in place allowing movement as contractions mix and move contents along GI tract).

3. Falciform ligament: attaches liver to anterior abdominal wall and diaphragm.

4. Greater omentum: attachments along the stomach and duodenum-extends downward anterior to small intestine then turns and extends up and attaches to transverse colon; lymph nodes contribute macrophages and antibody-producing plasma cells that combat and contain infections of the GI tract.