In the large intestine the absorption of water continues until semisolid consistency of faeces is achieved. Mineral salts, vitamins and some drugs are also absorbed into the blood capillaries from the large intestine. The large intestine is heavily colonized by certain types of bacteria which synthesize vitamin K and Folic acid. Unabsorbed carbohydrate undergoes bacterial fermentation and produces gas. These gases pass out of the bowel as flatus. The large intestine exhibits mass movements.
Movements of the Gastro Intestinal Tract
Deglutition is the process by which the masticated food is transported across the pharynx and reaches the stomach. Due to contractile movements of the stomach, the food is well mixed up with gastric juice. After being in the stomach for 3 or 4 hours the pyloric sphincter opens pushing the food into the duodenum.
The small intestine shows three important types of movements, they are -
1. Pendular Movement
These movements are induced by contraction of the circular and longitudinal muscles of the intestine. This movement contributes to the thorough mixing of chyme with the digestive juice.
2. Segmenting Movement
This movement occurs by the contraction of the circular muscles which produces transverse folds, dividing the intestine into short segments.
3. Peristaltic Movement
It is the wavelike contraction of the alimentary canal which propels the food through the gastro intestinal tract.