MOTILITY AND ASSOCIATED DISORDERS OF THE GASTRO INTESTINAL SYSTEM

ABSTRACT

The Gastro intestinal system is vital for overall secretions,

digestion, absorption, and movement within the tracts. Secretions involve

release of fluids, chemicals and catalytic substances that facilitates

digestion and related gastrointestinal tract (GIT) activities. Digestion

involves hydrolysis of condensed products of carbohydrates, proteins and fats.

Absorption involves movement of molecules across the GIT into the circulatory

system. Carbohydrates are hydrolysed to monosaccharides; Proteins to amino

acids; and Fats to fatty acids and glycerols (Guyton and Hall, 2006; Seeley,

Stephens & Tate, 2008). Not all molecules are however are broken down

before being absorbed (e.g. vitamins, minerals and water); absorption of

certain molecules can occur along the digestive tract but most absorption

occurs in the duodenum and jejunum, though some absorption occurs in the ileum.

The

surface of the duodenum is modified in several ways that increase its surface

area about 600-1000fold to allow for more efficient digestion and absorption of

food. These various modifications greatly increase the surface area of the

small intestine and thus greatly enhance absorption. Most end-products of digestion as well as vitamins, minerals

and water are absorbed in the small intestinal lumen by four mechanisms for

absorption: (1) active transport, (2) passive diffusion, (3) endocytosis, and

(4) facilitative diffusion (Inse et al., 2004). Absorption of amino acids occurs

rapidly in the duodenum and jejunum but slow in the ileum.  Absorption of long-chain fatty acids is

greatest in the duodenum and jejunum, but appreciable amounts are also absorbed

in the ileum. (Ganong, 2006) The vast bulk of mineral absorption occurs in the

small intestine. Some drugs can rapidly dissolve or disintegrate in the oral cavity

(Orodispersible tablets), others are absorbed from the pharynx and ooesophagus

as the saliva passes down into the stomach.

Table Of Contents

• Introduction
• Motility In The Mouth
• Pharyngeal And Oesophageal
  
  Motility
• Motility In The Stomach
• Motility In The Small Intestine
• Motility In The Large Intestine
• Regulation Of Gastrointestinal
  
  Motility
• Intestinal Motility Disorders
• Conclusion

References