BIOC33H3 Study Guide - Quiz Guide: Medical Ultrasound, Radiodensity, Bilirubin
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Chapter 39: Gastrointestinal System
STRUCTURES AND FUNCTIONS
The main function of the gastrointestinal (GI) system is to supply nutrients to body cells.
The GI tract is innervated by the autonomic nervous system. The parasympathetic system is
mainly excitatory, and the sympathetic system is mainly inhibitory.
The two types of movement of the GI tract are mixing (segmentation) and propulsion
The secretions of the GI system consist of enzymes and hormones for digestion, mucus
to provide protection and lubrication, water, and electrolytes.
o The mouth consists of the lips and oral (buccal) cavity.
o The main function of saliva is to lubricate and soften the food mass, thus
Pharynx: a musculomembranous tube that is divided into the nasopharynx, oropharynx,
and laryngeal pharynx.
o A hollow, muscular tube that receives food from the pharynx and moves it to the
stomach by peristaltic contractions.
o Lower esophageal sphincter (LES) at the distal end remains contracted except
during swallowing, belching, or vomiting.
o The functions are to store food, mix the food with gastric secretions, and empty
contents into the small intestine at a rate at which digestion can occur.
o The secretion of HCl acid makes gastric juice acidic.
o Intrinsic factor promotes cobalamin absorption in the small intestine.
Small intestine: two primary functions are digestion and absorption.
o The four parts are (1) the cecum and appendix; (2) the colon (ascending,
transverse, descending, sigmoid colon); (3) the rectum; and (4) the anus.
o The most important function of the large intestine is the absorption of water and
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