1. Mouth: The mouth is the first part of the alimentary canal and is responsible for ingesting food. It consists of the lips, teeth, tongue, and palate, which work together to break down food into smaller pieces and mix it with saliva to form a soft, digestible mass called a bolus.
2. Esophagus: The esophagus is a muscular tube that connects the mouth to the stomach. It carries the bolus from the mouth to the stomach by a process called peristalsis, a series of involuntary muscle contractions that push the food down the esophagus.
3. Stomach: The stomach is a J-shaped organ located on the left side of the abdomen. It receives the bolus from the esophagus and stores it temporarily. The stomach also produces gastric juices, which contain hydrochloric acid and enzymes, that help to break down proteins and other complex food components. The churning and mixing action of the stomach muscles further breaks down the food into a semi-liquid substance called chyme.
4. Small Intestine: The small intestine is the longest part of the alimentary canal and is responsible for most of the absorption of nutrients from digested food. It consists of three sections: the duodenum, jejunum, and ileum. The duodenum is the first part of the small intestine and receives chyme from the stomach. It is where further digestion occurs with the help of enzymes from the pancreas and bile from the liver. The jejunum and ileum are responsible for the majority of nutrient absorption through their inner lining, which contains numerous small, finger-like projections called villi.
5. Large Intestine: The large intestine is shorter and wider than the small intestine and primarily functions to absorb water, electrolytes, and some vitamins from the undigested material. It also stores waste products in the form of feces until they are eliminated through the anus. The main parts of the large intestine are the cecum, colon, and rectum.